REVIEWS Open Access

Fungi of entomopathogenic potential inChytridiomycota and Blastocladiomycotaand in fungal allies of the Oomycota andMicrosporidiaAgata Kaczmarek1 and Mieczysława I Boguś12

Abstract

The relationship between entomopathogenic fungi and their insect hosts is a classic example of the co-evolutionary arms race between pathogen and target host The present review describes the entomopathogenicpotential of Chytridiomycota and Blastocladiomycota fungi and two groups of fungal allies Oomycota andMicrosporidia The Oomycota (water moulds) are considered as a model biological control agent of mosquito larvaeDue to their shared ecological and morphological similarities they had long been considered a part of the fungalkingdom however phylogenetic studies have since placed this group within the Straminipila The Microsporidia areparasites of economically-important insects including grasshoppers lady beetles bumblebees colorado potatobeetles and honeybees They have been found to display some fungal characteristics and phylogenetic studiessuggest that they are related to fungi either as a basal branch or sister group The Blastocladiomycota andChytridiomycota named the lower fungi historically were described together however molecular phylogenetic andultrastructural research has classified them in their own phylum They are considered parasites of ants and of thelarval stages of black flies mosquitoes and scale insects

Keywords Biological control Host-specificity Insect pathogens

INTRODUCTIONThe interaction between host and parasite is charac-terised on the one hand by the parasites developingmore effective strategies of host exploitation and on theother by the hosts mounting increasingly robust de-fences though Red Queen dynamics or coevolutionaryarms races Furthermore depending on gene flow anddifferences in selection pressure between sites both hostand parasite may demonstrate local adaptation to theircounterpart or develop more general resistance or offen-sive traits (Kaur et al 2019)

Although chemical pesticides have been used for thecontrol of insect pests for many decades they are knownto exert side effects on non-target organisms contamin-ate groundwater and leave residues on food crops theyare also believed to support the development of insectresistance Therefore there is currently great interest inthe development of alternative methods for integratedpest management (Kim et al 2017 Mužinić and Želježić2018 Neuwirthovaacute et al 2019) More recent studies havefound entomopathogens to regulate many populations ofarthropods (Lacey et al 2001 Lacey et al 2015 Lacey2016) and that entomopathogenic fungi themselves mayplay a role in removing harmful substances and heavymetals from the environment (Litwin et al 2020)The success of using an entomopathogenic fungus as a

myco-biocontrol agent depends on the selection of a

copy The Author(s) 2021 Open Access This article is licensed under a Creative Commons Attribution 40 International Licensewhich permits use sharing adaptation distribution and reproduction in any medium or format as long as you giveappropriate credit to the original author(s) and the source provide a link to the Creative Commons licence and indicate ifchanges were made The images or other third party material in this article are included in the articles Creative Commonslicence unless indicated otherwise in a credit line to the material If material is not included in the articles Creative Commonslicence and your intended use is not permitted by statutory regulation or exceeds the permitted use you will need to obtainpermission directly from the copyright holder To view a copy of this licence visit httpcreativecommonsorglicensesby40

Correspondence aga_kaczmtwardapanpl1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw PolandFull list of author information is available at the end of the article

IMA FungusKaczmarek and Boguś IMA Fungus (2021) 1229 httpsdoiorg101186s43008-021-00074-y

virulent and stable strain with specific efficacy for thetarget host Hence there has been considerable interestin the creation of new strains of entomopathogenicfungi accompanied by the development of fermentationsystems for optimal biomass production and the designof delivery systems suitable for both the microorganismand common agricultural practices One key step in thedevelopment of effective strains involves the cloning ofgenes that can enhance pathogenesis (St Leger andWang 2010 Jaronski and Mascarin 2017 Dobrowolskiet al 2018 Karaboumlrkluuml et al 2018)The co-evolution of fungi and insects over hundreds

of millions of years has resulted in the development of awide range of complex and intricate interactions be-tween them (Joop and Vilcinskas 2016) Entomopatho-genic fungi have evolved to infect a wide range of insectsin all developmental stages (viz eggs larvae pupaenymphs and imago) across a range of niches Suchadaptability requires considerable morphological diver-sity resulting in a wide range of fungal species withmorphological phylogenetic and ecological diversityHowever although recent advances in the genome biol-ogy of entomopathogenic fungi indicate the geneticbases of their adaptation to insect hosts and host rangesas well as the evolutionary relationships between insectand non-insect pathogens (Arauacutejo and Hughes 2016Wang and Wang 2017) the mechanisms of host specifi-city in pathogenic microbiology generally remain poorlyunderstood

EVOLUTION OF ENTOMOPATHOGENIC FUNGIFrom an evolutionary point of view entomopathogenicfungi do not constitute a monophyletic group Insteadphylogenetic data suggests that entomopathogenic activ-ity has arisen independently and frequently along thecourse of fungal evolution (Humber 2008 Arauacutejo andHughes 2016 Moonjely et al 2016) Wang and Wang(Wang and Wang 2017) proposed that this evolutionarypattern is indicative of frequent cross-kingdom or cross-phylum host jumping during fungal pathogen speciationSuch phenomena may be explained by the host-habitathypothesis or the host-relatedness hypothesis The host-habitat hypothesis suggests that entomopathogens acci-dently switch between host organisms living in a com-mon environment this better explains the dynamicevolution of host diversification and adaptation in theHypocreales (Nikoh and Fukatsu 2000 Spatafora et al2007 Blackwell 2010) In contrast the host-relatednesshypothesis suggests that pathogens change hosts to newspecies closely related with the original host (Nikoh andFukatsu 2000 Kepler et al 2012)Historically the Fungi were divided into four phyla

however following dramatic changes in higher-level tax-onomy in the last 20 years the number of fungal phyla

has tripled to 12 organized into six major groupsDikarya Mucoromycota Zoopagomycota Blastocladio-mycota Chytridiomyceta and Opisthosporidia (Jameset al 2020) It has been estimated that about 750 speciesof entomopathogenic fungi exist most of which are dis-tributed in the phyla Chytridiomycota Blastocladiomy-cota Zoopagomycota Basidiomycota and AscomycotaSome authors have also traditionally included the Micro-sporidia and the ecologically-similar butphylogenetically-distinct Oomycota (water moulds) be-longing to the Straminipila

OOMYCOTAThe Oomycota are a genetically and morphologically-diverse clade that can form hyphae or exist as simpleholocarpic thalli the phylum contains at least 1500 spe-cies of fungus in 100 genera (Beakes and Thines 2017)The oomycetes are filamentous eukaryotic microorgan-isms belonging to the kingdom Straminipila howeversome authors placed them among the fungi based ontheir ecological and morphological characteristics vizfilamentous growth habit nutrition by absorption andreproduction via spores (Rossman and Palm 2006Beakes et al 2012 Thines 2018) Unlike the true fungithe cell walls of the oomycetes are composed of cellulosederivatives that serve as structural components ratherthan chitin (Hassett et al 2019 Klinter et al 2019) Sex-ual reproduction typically occurs between gametangia(antheridia and oogonia) on the same or different hy-phae (Rocha et al 2018 Spring et al 2018) howeverthis is not always the case Periplasma isogametum forexample demonstrates a type of sexual reproduction in-volving morphological isogamy and physiological anisog-amy (Martin and Warren 2020) Most oomycetes arealso capable of asexual reproduction via their kidneybean-shaped biflagellate zoospores with apically orlaterally-attached whiplash and tinsel flagella (hetero-konts) (Walker and van West 2007) Interestingly themitochondria of the oomycetes possess tubular cristaeas opposed to the disc-like cristae of the fungi (Powellet al 1985 Karlovsky and Fartmann 1992 Weber et al1998 Rossman and Palm 2006)Pathogenic oomycetes are able to infect a broad

range of algae plants protists fungi arthropods andvertebrates including humans and can cause lossesin agriculture and aquaculture (Mendoza and Vilela2013 van West and Beakes 2014 Kamoun et al2015) Twelve species of entomopathogenic Oomycotaare known to exist within six genera Lagenidium (Lgiganteum) Leptolegnia (L caudata and L chapma-nii) Pythium (P carolinianum P sierrensis and Pflevoense) Crypticola (C clavulifera and C entomo-phaga) Couchia (C amphora C linnophila and Ccircumplexa) and Aphanomyces (A laevis) (Arauacutejo

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 2 of 13

and Hughes 2016 Mendoza et al 2018) Most arefacultative parasites of mosquito larvae belonging tothe genera Anopheles Culex Aedes OchlerotatusCuliseta Orthopodomyia Uranotaenia Psorophoraand Mansonia (Frances et al 1989 Woodring et al1995 Scholte et al 2004 Patwardhan et al 2005Vyas et al 2007 Singh and Prakash 2012 Vilela et al2018 Shen et al 2019 Vilela et al 2019 Shen et al2020a) Some examples of infected insects are listedin Table 1The most well-known and thoroughly-analysed en-

tomopathogenic Oomycota is arguably L giganteumwhich was used as a biological control model of mos-quito larvae (Vilela et al 2019) Infection is initiatedby free-floating zoospores formed in sporangia whichare released only in aqueous environments (Walkerand van West 2007) The spores are responsible forrecognising and binding to the host cuticle After suc-cessful binding they swell germinate and penetratethe insect exoskeleton The mycelia grow through thehemocoel resulting in the death of the insect whilethe fungus terminates with reproduction and the sub-sequent release of infectious zoospores Successful in-fection requires the production of hydrolytic enzymessuch as chitinases (Shen et al 2020b) hexosamini-dases (Dowd et al 2007 Olivera et al 2016) or glyco-side hydrolase family 5 subfamily 27 (GH5_27) whichplay crucial roles in the cuticle-degrading process(Quiroz Velasquez et al 2014) Other important en-zymes produced by entomopathogenic oomycetes aretrehalases which not only take part in cuticle degrad-ation but may also hasten the infection process bydepleting trehalose the most abundant sugar sourcein insect hemolymph (McInnis and Domnas 1973)It is possible that the ancestors of L giganteum

were plant pathogens as sequence analyses have indi-cated the presence of genes characteristic of plant tis-sue infections such as crn or cbel However othergenes coding cuticle-degrading enzymes have beenfound such as GH5_27 or GH20 these are character-istic of entomopathogens and are not observed inplant pathogens (Quiroz Velasquez et al 2014 Oli-vera et al 2016) This dichotomy suggests that fungaland oomycete entomopathogens not only sharemorphology and pathological strategies but also evo-lutionary histories and ecological relationships (Leoro-Garzon et al 2019 Shen et al 2019)L giganteum was used as a control agent against mos-

quito larvae in the commercial product Laginex whichwas registered and released in the USA in 1995 (Hallmonet al 2000) however due to several cases of life-threatingmycoses in dogs recorded in the southern United Statesthe product was later deregistered and is no longer for sale(Mendoza and Vilela 2013 Vilela et al 2015 Vilela et al

2019) Recent data has shown the existence of two formsof L giganteum (Vilela et al 2015) the heat-tolerant taxonL giganteum f caninum pathogenic to mammals (Spieset al 2016) and L giganteum f giganteum which can in-fect mosquito larvae in nature Both taxa share a commonancestor and can infect mosquito larvae the only pheno-typic difference between the two types is their tolerancefor growth at different temperatures the latter does nottolerate human body temperature (37degC) but develops wellat 25degC and below (Vilela et al 2015 Vilela et al 2019)Oomycetes have also been found to infect non-dipteran

insects for example Crypticola entomophaga has been ob-served to attack aquatic insects from the order Trichop-tera (caddis flies Dick 2003 Gani et al 2019)

MICROSPORIDIAMicrosporidia are unicellular eukaryotes living as obli-gate intracellular parasites All stages of their life-cycleassociated with growing and replication can only takeplace inside host cells in the environment they can sur-vive only as thick-walled spores (Timofeev et al 2020)Their adaptation to a parasitic strategy has resulted inthe development of a seemingly paradoxical mixture ofcharacteristics the cells lack mitochondria and theirmetabolism does not employ electron transfer chainsoxidative phosphorylation or the tricarboxylic acid(TCA) cycle In addition their genomes are poor ingenes involved in resource-producing metabolic path-ways such as ATP synthesis but rich in others that en-hance transport mechanisms and allow resources to behijacked from the host Due to their highly-reducedmorphology ultrastructure biochemistry and metabol-ism as well as their considerably impoverished genomemicrosporidia need to induce considerable disruption ofhost cell physiology to enable successful infection anddevelopment (Corradi 2015 Haag et al 2019 Timofeevet al 2020) One exception to this rule is Microspori-dium daphniae which has been found to possess a mito-chondrial genome and the genes necessary forproducing ATP from glucose (Haag et al 2014)Of all known parasites those of Microsporidia are ar-

guably the most host dependent (Corradi and Keeling2009 Keeling 2009 Tamim El Jarkass and Reinke 2020)and this dependence may account for their developmentof a range of mechanisms to ensure intracellular sur-vival For example they demonstrate reduced expressionof immune-peptide or immune-related genes (Antuacutenezet al 2009) reduced re-epithelization in infected ventric-uli (Higes et al 2007 Garciacutea-Palencia et al 2010) in-creased energetic stress (Mayack and Naug 2009Martiacuten-Hernaacutendez et al 2011) and inhibited melanisa-tion in the hemolymph of infected Bombyx mori larvae(Wu et al 2016)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 3 of 13

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms

Infected insect species Literature data

Oomycota

Aphanomyces laevis Mosquito larvae (Patwardhan et al 2005)

Couchia spp (Wallace Martin 2000)

Crypticola spp (Frances 1991 Dick 2003 Mendoza et al 2018)

Lagenidium giganteum (Golkar et al 1993 Vyas et al 2007 Vilela et al 2019)

Leptolegnia caudata spp (Bisht et al 1996 Montalva et al 2016 Gutierrez et al2017)

Pythium spp (Clark et al 1966 Su et al 2001 Su 2008 Shen et al2019)

Microsporidia

Anncaliia algerae Drosophila melanogaster (Sokolova et al 2020)

Antonospora locustae(Nosema locustae)

Grasshoppers (Lange 2005 Zhou and Zhang 2009 Gerus et al 2020)

Nosema adaliae Two-spotted lady beetle Adalia bipunctata (ColeopteraCoccinellidae)

(Steele and Bjoslashrnson 2014)

Nosema alticae Flea beetle Altica hampei (Coleoptera Chrysomelidae) (Yıldırım and Bekircan 2020)

Nosema bombi Nosemaceranae Tubulinosemapampeana

Bumblebees (Brown 2017)

Nosema carpocapsae Codling moth Cydia pomonella L (Zimmermann et al 2013)

Nosema leptinotarsae Colorado potato beetle Leptinotarsa decemlineata Say(Coleoptera Chrysomelidae)

(Bekircan 2020)

Nosema maddoxi Brown marmorated stink bug Halyomorpha halys (HemipteraPentatomidae)

(Preston et al 2020b Preston et al 2020a)

Nosema pernyi The Chinese oak silkworm Antheraea pernyi (LepidopteraSaturniidae)

(Liu et al 2020)

Nosema pyrausta European corn borer Ostrinia nubilalis the Asian corn borerOstrinia furnacalis and the adzuki bean borer Ostrinia scapulalis

(Grushevaya et al 2018 Grushevaya et al 2020)

TubuliNosema sp Loxostege sticticalis L (Lepidoptera Crambidae) (Malysh et al 2018)

TubuliNosema suzukii Drosophila suzukii (Biganski et al 2020)

Vairimorpha (Nosema)ceranae Vairimorpha(Nosema) apis

Honeybee Apis mellifera (Forsgren and Fries 2010 Tokarev et al 2018Applegate and Petritz 2020 Chang et al 2020Ostroverkhova et al 2020)

Chytridiomycota

Myrmicinosporidiumdurum

Ants from Subfamilies Myrmicinae Formicinae andDolichoderinae

(Sanchez-Pentildea et al 1993 Gonccedilalves et al 2012Trigos-Peral et al 2017)

Nephridiophaga maderaeNephridiophagaarchimandritaNephridiophagalucihormeticaNephridiophaga blattellaeNephridiophaga blaberi

Madeira cockroach (Leucophaea maderae)Archimandrita tessellateLucihormetica verrucoseGerman cockroach Blattella germanicaDeathrsquos head cockroach Blaberus craniifer

(Radek et al 2017)(Radek et al 2011)(Radek and Herth 1999)(Fabel et al 2000)

Blastocladiomycota

Coelomycidium simulii Larval stage of black flies (Diptera) Simulium asakoae Schamlongi S chiangmaiense S fenestratum S feuerborni Snakhonense S nodosum S quinquestriatum S tani and Sjaponicum

(Levchenko et al 1974 Kim 2011 Jitklang et al 2012Kim 2015 Adler and McCreadie 2019)

Coelomomyces africanusCoelomomyces angolensisCoelomomyces iliensisCoelomomyces indicusCoelomomyces iraniCoelomomyces lairdi

Mosquito larvae from species of Culex Culiseta Aedes AnophelesPsorophora and Uranotaenia

(Scholte et al 2004 Balaraman et al 2006 Rueda-Paacuteramo et al 2017 Dahmana and Mediannikov 2020Gao et al 2020)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 4 of 13

The life-cycle of microsporidia is characterized bythree phases an infective or environmental phase(spores) a merogony (proliferative) phase and a sporo-gonic or spore-forming phase (Keeling and Fast 2002)Microsporidia spores are first ingested or inhaled by thehost The spores then germinate and produce a long andconvoluted tubule extrusion apparatus (polar tubule)this tubule distinguishes them from other organisms andplays a crucial role in host cell invasion The spore ap-proaches the host cell and its polar tubule is everted toenter the cell and inject its sporoplasm into the host cellcytoplasm Following successful injection the prolifera-tive phase begins this phase includes all cell growth anddivision from the sporoplasm until spore formation It isknown to include two possible processes schizogonyand merogony Although very little is understood ofschizogony in Oomycota merogony is known to takeplace as the injected sporoplasm develops into meronts(the proliferative stage) these in turn multiply by binaryfission or multiple fission depending on the species toform multinucleate plasmodial forms Finally theseforms undergo sporogony with the meronts developinginto sporonts which produce two or more sporoblaststhese in turn undergo metamorphosis into sporesInterestingly unlike other species in which sporogony

occurs in the presence of plasmalemmal thickening themicrosporidia undergo sporogony to produce diplokar-yotic nuclei after meiosis These sporonts can multiplyby binary or multiple fission acquire specialized organ-elles and become spores Subsequently the spores con-tinue the cycle by spreading through the tissues of thehost infecting new cells (Lallo et al 2016 Han andWeiss 2017 Han et al 2020 Horta et al 2020)Traditionally Microsporidia were classified within the

phylum Apicomplexa as sporozoan parasites howeverphylogenetic studies suggest that microsporidia are relatedto fungi either as a basal branch or sister group (Lee et al2008 Han and Weiss 2017) They have also been found toinclude chitin in the spore wall and use trehalose as a

sugar reserve and studies have noted the presence ofclosed mitosis spindle pole bodies and meiosis (Han andWeiss 2017) Although they can infect a great number ofdomestic and wild animals the most common hosts arearthropods and fish Since their discovery in the 1850s asthe causative agent of the silkworm disease pebrine orpepper disease which devastated the silk industry in Eur-ope these pathogens have demonstrated major economicsignificance in animal farming such as nosemosis in bee-keeping (Nosema aApis and N ceranae) and microspori-diosis in aquaculture (Loma salmonae for salmonids andThelohania spp for shrimp) Nosema bombycis has alsobeen found to infect the domesticated silkworm Bombyxmori In addition some microsporidia act as opportunisticpathogens of humans especially in patients with AIDS(Weiss 2020)About 93 genera of microsporidia have the ability to

infect insects (Becnel and Andreadis 2014) They areconsidered as biological control agents for regulating thepopulation of the beet webworm Loxostege sticticalis re-sponsible for serious damage to crops such as soybeansugar beet alfalfa and sunflower in northern Eurasia(Malysh et al 2020) Interestingly some authors con-sider microsporidia to have enabled the invasive successof the ladybird Harmonia axyridis (Vilcinskas et al2015 Verheggen et al 2017) in which the microsporidiaact as a symbiotic ldquobiological weaponrdquo against somepredators like Coccinella septempunctata and Adaliabipunctata (Ceryngier et al 2018) Some examples of in-fected insects are listed in Table 1Also Antonospora locustae formerly known as No-

sema locustae (syn Paranosema locustae) is commonlyused as a biological control agent for grasshoppers inthe commercial products Nolo Bait and Semaspore(Lange 2005 Zhou and Zhang 2009 Solter et al 2012)Like other microsporidial pathogens A locustae alsoneeds to control the metabolic processes and molecularprogrammes of the host in order to proliferate Success-ful infection was found to suppress the locust gut

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms (Continued)

Infected insect species Literature data

Coelomomyces maclaeyaeCoelomomyces numulariusCoelomomyces opifexCoelomomycespentangulatusCoelomomycespolynesiensisCoelomomyces punctatusCoelomomyces solomonisCoelomomycessantabrancae spp

Myiophagus cf ucrainicus Scale insect Caribbean black scale Saissetia neglecta (Hemiptera)Caliphornia red scale Aonidiella aurantii (Hemiptera)Chironomus atracinus larvae

(Moore and Duncan 2017)(Czeczuga and Godlewska 2001)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 5 of 13

microbiota including the gut bacteria that produce ag-gregation pheromones thus preventing host aggregation(Pan et al 2018)Most microsporidia species require two successive

host generations to complete their life-cycle and at leastthree genera viz Amblyospora Hyalinocysta and Para-thelohania also require development in an intermediatecopepod host (Becnel and Andreadis 2014) These gen-era are also highly host- and tissue-specific with com-plex developmental sequences comprising unique stagesand events (Becnel et al 2005) They are mostly patho-gens of mosquito larvae (Andreadis 1985 Andreadis2007 Shen et al 2020a) interestingly microsporidian in-fection has also been found to be associated with a re-duction in Plasmodium falciparum transmission inAnopheles arabiensis mosquitoes (Herren et al 2020)In contrast some species of microsporidia exhibit sim-

ple life-cycles with a single spore type responsible fororal (horizontal) transmission these affect only one gen-eration of insects and are not usually host or tissue spe-cific (Becnel et al 2005) A good example of a genuswith this simple life-cycle is Nosema including the spe-cies N apis and N ceranae These species are respon-sible for most microsporidian infections in bees andother species of Hymenoptera resulting in ecologicaland economical losses in apiculture (Higes et al 2006Forsgren and Fries 2010 Grupe and Alisha Quandt2020 Ostroverkhova et al 2020 Paudel et al 2020)Interestingly phylogenetic studies have placed the No-sema species able to infect bees within a new genusVairimorpha (Tokarev et al 2020)N apis is believed to have long been a parasite of the

European honeybee Apis mellifera whereas N ceranaeis presumed to have more recently undergone a hostshift to A mellifera from the Asian honeybee A ceranae(Buczek et al 2020 Ostroverkhova et al 2020) The par-asites exhibit a tissue tropism for honey bee ventriculus(Higes et al 2020) and are believed to infect their ven-tricular epithelial cells during digestion infected beessuffer impaired nutrient absorption resulting in energyloss and death by starvation (Valizadeh et al 2020)Nosema pernyi a microsporidium infecting the Chin-

ese oak silkworm Antheraea pernyi can enter the gutcell by polar tube infection in most situations The sporein the polar tube germinates within the alkaline environ-ment of the intestine inducing destructive chronic dis-ease (Wang et al 2019 Han et al 2020) It is alsopossible for the parasite to exploit the metabolism of thehost cell to progress its own life-cycle A recent studyfound that successful infection of the honeybee midgutby the microsporidian pathogen N ceranae involves theinhibition of apoptosis (Higes et al 2013 Kurze et al2018) in such cases the parasite appears to inhibitapoptosis by regulating the genes involved in the

process as well as in the cell cycle (Martiacuten-Hernaacutendezet al 2017) thus increasing oxidative stress and antioxi-dant enzyme generation in the gut and inhibiting thegenes involved in the homeostasis and renewal of intes-tinal tissues (Dussaubat et al 2012 Liu et al 2020)Microsporidial infection can also alter host metabol-

ism and induce both local and systemic innate immuneresponses (Pan et al 2018) For example N ceranae in-fection is believed to suppress immune defence mecha-nisms in honey bees studies have indicated thatinfection downregulates some immune-related genes in-cluding abaecin apidecin defensin hymenoptaecin glu-cose dehydrogenase (GLD) and vitellogenin (Vg) andupregulates Jun-related antigen Jra and pi3k (Changet al 2020) Additionally transcription of the inhibitorof apoptosis protein (iap-2) gene was found to be upreg-ulated in Nosema-tolerant honeybees (Kurze et al 2015)it is possible that inhibition of apoptosis might help theparasites optimize their environment and extend theperiod during which they can grow and differentiatewithin host cells (Higes et al 2013) It also appears thatpheromone production in worker and queen honeybeesto be modified during infection (Dussaubat et al 2013)

CHYTRIDIOMYCOTAThe Chytridiomycota comprise zoosporic fungi phylogenet-ically related to the true fungi This group comprises at leastthree major lineages of chytrids (1) Rozella spp the earliestdiverging lineage in kingdom Fungi (2) Olpidium brassicaethe only species classified in Zygomycota and (3) the corechytrid clade encompassing the remaining orders and fam-ilies and most flagellated fungi including those of Chytri-diales Spizellomycetales pp Monoblepharidales andNeocallimastigales (Barr 2001 James et al 2006) Chytridsare unicellular colonial or filamentous organisms with ab-sorptive nutrition and which reproduce through the produc-tion of motile zoospores typically propelled by a singleposteriorly-directed flagellum (Barr 2001)Infection begins with the attachment of a motile

zoospore to the surface of a host cell and the forma-tion of a thickened wall around the zoospore In asuccessful infection the encysted zoospore will de-velop into a mature sporangium following which agerm tube typically forms which enters the host cellvia the girdle zone The zoospores form within thehost cell and are released to infect other cells by de-hiscence The attached zoospores completely dependon the host cell for nourishment and their develop-ment into mature sporangia (Ibelings et al 2004)Traditionally Chytridiomycota have been regarded as

aquatic fungi (Ibelings et al 2004) but most speciesoccur in soil as saprophytes growing on organic material(Digby et al 2010) In addition certain obligate

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 6 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

and Hughes 2016 Mendoza et al 2018) Most arefacultative parasites of mosquito larvae belonging tothe genera Anopheles Culex Aedes OchlerotatusCuliseta Orthopodomyia Uranotaenia Psorophoraand Mansonia (Frances et al 1989 Woodring et al1995 Scholte et al 2004 Patwardhan et al 2005Vyas et al 2007 Singh and Prakash 2012 Vilela et al2018 Shen et al 2019 Vilela et al 2019 Shen et al2020a) Some examples of infected insects are listedin Table 1The most well-known and thoroughly-analysed en-

tomopathogenic Oomycota is arguably L giganteumwhich was used as a biological control model of mos-quito larvae (Vilela et al 2019) Infection is initiatedby free-floating zoospores formed in sporangia whichare released only in aqueous environments (Walkerand van West 2007) The spores are responsible forrecognising and binding to the host cuticle After suc-cessful binding they swell germinate and penetratethe insect exoskeleton The mycelia grow through thehemocoel resulting in the death of the insect whilethe fungus terminates with reproduction and the sub-sequent release of infectious zoospores Successful in-fection requires the production of hydrolytic enzymessuch as chitinases (Shen et al 2020b) hexosamini-dases (Dowd et al 2007 Olivera et al 2016) or glyco-side hydrolase family 5 subfamily 27 (GH5_27) whichplay crucial roles in the cuticle-degrading process(Quiroz Velasquez et al 2014) Other important en-zymes produced by entomopathogenic oomycetes aretrehalases which not only take part in cuticle degrad-ation but may also hasten the infection process bydepleting trehalose the most abundant sugar sourcein insect hemolymph (McInnis and Domnas 1973)It is possible that the ancestors of L giganteum

were plant pathogens as sequence analyses have indi-cated the presence of genes characteristic of plant tis-sue infections such as crn or cbel However othergenes coding cuticle-degrading enzymes have beenfound such as GH5_27 or GH20 these are character-istic of entomopathogens and are not observed inplant pathogens (Quiroz Velasquez et al 2014 Oli-vera et al 2016) This dichotomy suggests that fungaland oomycete entomopathogens not only sharemorphology and pathological strategies but also evo-lutionary histories and ecological relationships (Leoro-Garzon et al 2019 Shen et al 2019)L giganteum was used as a control agent against mos-

quito larvae in the commercial product Laginex whichwas registered and released in the USA in 1995 (Hallmonet al 2000) however due to several cases of life-threatingmycoses in dogs recorded in the southern United Statesthe product was later deregistered and is no longer for sale(Mendoza and Vilela 2013 Vilela et al 2015 Vilela et al

2019) Recent data has shown the existence of two formsof L giganteum (Vilela et al 2015) the heat-tolerant taxonL giganteum f caninum pathogenic to mammals (Spieset al 2016) and L giganteum f giganteum which can in-fect mosquito larvae in nature Both taxa share a commonancestor and can infect mosquito larvae the only pheno-typic difference between the two types is their tolerancefor growth at different temperatures the latter does nottolerate human body temperature (37degC) but develops wellat 25degC and below (Vilela et al 2015 Vilela et al 2019)Oomycetes have also been found to infect non-dipteran

insects for example Crypticola entomophaga has been ob-served to attack aquatic insects from the order Trichop-tera (caddis flies Dick 2003 Gani et al 2019)

MICROSPORIDIAMicrosporidia are unicellular eukaryotes living as obli-gate intracellular parasites All stages of their life-cycleassociated with growing and replication can only takeplace inside host cells in the environment they can sur-vive only as thick-walled spores (Timofeev et al 2020)Their adaptation to a parasitic strategy has resulted inthe development of a seemingly paradoxical mixture ofcharacteristics the cells lack mitochondria and theirmetabolism does not employ electron transfer chainsoxidative phosphorylation or the tricarboxylic acid(TCA) cycle In addition their genomes are poor ingenes involved in resource-producing metabolic path-ways such as ATP synthesis but rich in others that en-hance transport mechanisms and allow resources to behijacked from the host Due to their highly-reducedmorphology ultrastructure biochemistry and metabol-ism as well as their considerably impoverished genomemicrosporidia need to induce considerable disruption ofhost cell physiology to enable successful infection anddevelopment (Corradi 2015 Haag et al 2019 Timofeevet al 2020) One exception to this rule is Microspori-dium daphniae which has been found to possess a mito-chondrial genome and the genes necessary forproducing ATP from glucose (Haag et al 2014)Of all known parasites those of Microsporidia are ar-

guably the most host dependent (Corradi and Keeling2009 Keeling 2009 Tamim El Jarkass and Reinke 2020)and this dependence may account for their developmentof a range of mechanisms to ensure intracellular sur-vival For example they demonstrate reduced expressionof immune-peptide or immune-related genes (Antuacutenezet al 2009) reduced re-epithelization in infected ventric-uli (Higes et al 2007 Garciacutea-Palencia et al 2010) in-creased energetic stress (Mayack and Naug 2009Martiacuten-Hernaacutendez et al 2011) and inhibited melanisa-tion in the hemolymph of infected Bombyx mori larvae(Wu et al 2016)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 3 of 13

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms

Infected insect species Literature data

Oomycota

Aphanomyces laevis Mosquito larvae (Patwardhan et al 2005)

Couchia spp (Wallace Martin 2000)

Crypticola spp (Frances 1991 Dick 2003 Mendoza et al 2018)

Lagenidium giganteum (Golkar et al 1993 Vyas et al 2007 Vilela et al 2019)

Leptolegnia caudata spp (Bisht et al 1996 Montalva et al 2016 Gutierrez et al2017)

Pythium spp (Clark et al 1966 Su et al 2001 Su 2008 Shen et al2019)

Microsporidia

Anncaliia algerae Drosophila melanogaster (Sokolova et al 2020)

Antonospora locustae(Nosema locustae)

Grasshoppers (Lange 2005 Zhou and Zhang 2009 Gerus et al 2020)

Nosema adaliae Two-spotted lady beetle Adalia bipunctata (ColeopteraCoccinellidae)

(Steele and Bjoslashrnson 2014)

Nosema alticae Flea beetle Altica hampei (Coleoptera Chrysomelidae) (Yıldırım and Bekircan 2020)

Nosema bombi Nosemaceranae Tubulinosemapampeana

Bumblebees (Brown 2017)

Nosema carpocapsae Codling moth Cydia pomonella L (Zimmermann et al 2013)

Nosema leptinotarsae Colorado potato beetle Leptinotarsa decemlineata Say(Coleoptera Chrysomelidae)

(Bekircan 2020)

Nosema maddoxi Brown marmorated stink bug Halyomorpha halys (HemipteraPentatomidae)

(Preston et al 2020b Preston et al 2020a)

Nosema pernyi The Chinese oak silkworm Antheraea pernyi (LepidopteraSaturniidae)

(Liu et al 2020)

Nosema pyrausta European corn borer Ostrinia nubilalis the Asian corn borerOstrinia furnacalis and the adzuki bean borer Ostrinia scapulalis

(Grushevaya et al 2018 Grushevaya et al 2020)

TubuliNosema sp Loxostege sticticalis L (Lepidoptera Crambidae) (Malysh et al 2018)

TubuliNosema suzukii Drosophila suzukii (Biganski et al 2020)

Vairimorpha (Nosema)ceranae Vairimorpha(Nosema) apis

Honeybee Apis mellifera (Forsgren and Fries 2010 Tokarev et al 2018Applegate and Petritz 2020 Chang et al 2020Ostroverkhova et al 2020)

Chytridiomycota

Myrmicinosporidiumdurum

Ants from Subfamilies Myrmicinae Formicinae andDolichoderinae

(Sanchez-Pentildea et al 1993 Gonccedilalves et al 2012Trigos-Peral et al 2017)

Nephridiophaga maderaeNephridiophagaarchimandritaNephridiophagalucihormeticaNephridiophaga blattellaeNephridiophaga blaberi

Madeira cockroach (Leucophaea maderae)Archimandrita tessellateLucihormetica verrucoseGerman cockroach Blattella germanicaDeathrsquos head cockroach Blaberus craniifer

(Radek et al 2017)(Radek et al 2011)(Radek and Herth 1999)(Fabel et al 2000)

Blastocladiomycota

Coelomycidium simulii Larval stage of black flies (Diptera) Simulium asakoae Schamlongi S chiangmaiense S fenestratum S feuerborni Snakhonense S nodosum S quinquestriatum S tani and Sjaponicum

(Levchenko et al 1974 Kim 2011 Jitklang et al 2012Kim 2015 Adler and McCreadie 2019)

Coelomomyces africanusCoelomomyces angolensisCoelomomyces iliensisCoelomomyces indicusCoelomomyces iraniCoelomomyces lairdi

Mosquito larvae from species of Culex Culiseta Aedes AnophelesPsorophora and Uranotaenia

(Scholte et al 2004 Balaraman et al 2006 Rueda-Paacuteramo et al 2017 Dahmana and Mediannikov 2020Gao et al 2020)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 4 of 13

The life-cycle of microsporidia is characterized bythree phases an infective or environmental phase(spores) a merogony (proliferative) phase and a sporo-gonic or spore-forming phase (Keeling and Fast 2002)Microsporidia spores are first ingested or inhaled by thehost The spores then germinate and produce a long andconvoluted tubule extrusion apparatus (polar tubule)this tubule distinguishes them from other organisms andplays a crucial role in host cell invasion The spore ap-proaches the host cell and its polar tubule is everted toenter the cell and inject its sporoplasm into the host cellcytoplasm Following successful injection the prolifera-tive phase begins this phase includes all cell growth anddivision from the sporoplasm until spore formation It isknown to include two possible processes schizogonyand merogony Although very little is understood ofschizogony in Oomycota merogony is known to takeplace as the injected sporoplasm develops into meronts(the proliferative stage) these in turn multiply by binaryfission or multiple fission depending on the species toform multinucleate plasmodial forms Finally theseforms undergo sporogony with the meronts developinginto sporonts which produce two or more sporoblaststhese in turn undergo metamorphosis into sporesInterestingly unlike other species in which sporogony

occurs in the presence of plasmalemmal thickening themicrosporidia undergo sporogony to produce diplokar-yotic nuclei after meiosis These sporonts can multiplyby binary or multiple fission acquire specialized organ-elles and become spores Subsequently the spores con-tinue the cycle by spreading through the tissues of thehost infecting new cells (Lallo et al 2016 Han andWeiss 2017 Han et al 2020 Horta et al 2020)Traditionally Microsporidia were classified within the

phylum Apicomplexa as sporozoan parasites howeverphylogenetic studies suggest that microsporidia are relatedto fungi either as a basal branch or sister group (Lee et al2008 Han and Weiss 2017) They have also been found toinclude chitin in the spore wall and use trehalose as a

sugar reserve and studies have noted the presence ofclosed mitosis spindle pole bodies and meiosis (Han andWeiss 2017) Although they can infect a great number ofdomestic and wild animals the most common hosts arearthropods and fish Since their discovery in the 1850s asthe causative agent of the silkworm disease pebrine orpepper disease which devastated the silk industry in Eur-ope these pathogens have demonstrated major economicsignificance in animal farming such as nosemosis in bee-keeping (Nosema aApis and N ceranae) and microspori-diosis in aquaculture (Loma salmonae for salmonids andThelohania spp for shrimp) Nosema bombycis has alsobeen found to infect the domesticated silkworm Bombyxmori In addition some microsporidia act as opportunisticpathogens of humans especially in patients with AIDS(Weiss 2020)About 93 genera of microsporidia have the ability to

infect insects (Becnel and Andreadis 2014) They areconsidered as biological control agents for regulating thepopulation of the beet webworm Loxostege sticticalis re-sponsible for serious damage to crops such as soybeansugar beet alfalfa and sunflower in northern Eurasia(Malysh et al 2020) Interestingly some authors con-sider microsporidia to have enabled the invasive successof the ladybird Harmonia axyridis (Vilcinskas et al2015 Verheggen et al 2017) in which the microsporidiaact as a symbiotic ldquobiological weaponrdquo against somepredators like Coccinella septempunctata and Adaliabipunctata (Ceryngier et al 2018) Some examples of in-fected insects are listed in Table 1Also Antonospora locustae formerly known as No-

sema locustae (syn Paranosema locustae) is commonlyused as a biological control agent for grasshoppers inthe commercial products Nolo Bait and Semaspore(Lange 2005 Zhou and Zhang 2009 Solter et al 2012)Like other microsporidial pathogens A locustae alsoneeds to control the metabolic processes and molecularprogrammes of the host in order to proliferate Success-ful infection was found to suppress the locust gut

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms (Continued)

Infected insect species Literature data

Coelomomyces maclaeyaeCoelomomyces numulariusCoelomomyces opifexCoelomomycespentangulatusCoelomomycespolynesiensisCoelomomyces punctatusCoelomomyces solomonisCoelomomycessantabrancae spp

Myiophagus cf ucrainicus Scale insect Caribbean black scale Saissetia neglecta (Hemiptera)Caliphornia red scale Aonidiella aurantii (Hemiptera)Chironomus atracinus larvae

(Moore and Duncan 2017)(Czeczuga and Godlewska 2001)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 5 of 13

microbiota including the gut bacteria that produce ag-gregation pheromones thus preventing host aggregation(Pan et al 2018)Most microsporidia species require two successive

host generations to complete their life-cycle and at leastthree genera viz Amblyospora Hyalinocysta and Para-thelohania also require development in an intermediatecopepod host (Becnel and Andreadis 2014) These gen-era are also highly host- and tissue-specific with com-plex developmental sequences comprising unique stagesand events (Becnel et al 2005) They are mostly patho-gens of mosquito larvae (Andreadis 1985 Andreadis2007 Shen et al 2020a) interestingly microsporidian in-fection has also been found to be associated with a re-duction in Plasmodium falciparum transmission inAnopheles arabiensis mosquitoes (Herren et al 2020)In contrast some species of microsporidia exhibit sim-

ple life-cycles with a single spore type responsible fororal (horizontal) transmission these affect only one gen-eration of insects and are not usually host or tissue spe-cific (Becnel et al 2005) A good example of a genuswith this simple life-cycle is Nosema including the spe-cies N apis and N ceranae These species are respon-sible for most microsporidian infections in bees andother species of Hymenoptera resulting in ecologicaland economical losses in apiculture (Higes et al 2006Forsgren and Fries 2010 Grupe and Alisha Quandt2020 Ostroverkhova et al 2020 Paudel et al 2020)Interestingly phylogenetic studies have placed the No-sema species able to infect bees within a new genusVairimorpha (Tokarev et al 2020)N apis is believed to have long been a parasite of the

European honeybee Apis mellifera whereas N ceranaeis presumed to have more recently undergone a hostshift to A mellifera from the Asian honeybee A ceranae(Buczek et al 2020 Ostroverkhova et al 2020) The par-asites exhibit a tissue tropism for honey bee ventriculus(Higes et al 2020) and are believed to infect their ven-tricular epithelial cells during digestion infected beessuffer impaired nutrient absorption resulting in energyloss and death by starvation (Valizadeh et al 2020)Nosema pernyi a microsporidium infecting the Chin-

ese oak silkworm Antheraea pernyi can enter the gutcell by polar tube infection in most situations The sporein the polar tube germinates within the alkaline environ-ment of the intestine inducing destructive chronic dis-ease (Wang et al 2019 Han et al 2020) It is alsopossible for the parasite to exploit the metabolism of thehost cell to progress its own life-cycle A recent studyfound that successful infection of the honeybee midgutby the microsporidian pathogen N ceranae involves theinhibition of apoptosis (Higes et al 2013 Kurze et al2018) in such cases the parasite appears to inhibitapoptosis by regulating the genes involved in the

process as well as in the cell cycle (Martiacuten-Hernaacutendezet al 2017) thus increasing oxidative stress and antioxi-dant enzyme generation in the gut and inhibiting thegenes involved in the homeostasis and renewal of intes-tinal tissues (Dussaubat et al 2012 Liu et al 2020)Microsporidial infection can also alter host metabol-

ism and induce both local and systemic innate immuneresponses (Pan et al 2018) For example N ceranae in-fection is believed to suppress immune defence mecha-nisms in honey bees studies have indicated thatinfection downregulates some immune-related genes in-cluding abaecin apidecin defensin hymenoptaecin glu-cose dehydrogenase (GLD) and vitellogenin (Vg) andupregulates Jun-related antigen Jra and pi3k (Changet al 2020) Additionally transcription of the inhibitorof apoptosis protein (iap-2) gene was found to be upreg-ulated in Nosema-tolerant honeybees (Kurze et al 2015)it is possible that inhibition of apoptosis might help theparasites optimize their environment and extend theperiod during which they can grow and differentiatewithin host cells (Higes et al 2013) It also appears thatpheromone production in worker and queen honeybeesto be modified during infection (Dussaubat et al 2013)

CHYTRIDIOMYCOTAThe Chytridiomycota comprise zoosporic fungi phylogenet-ically related to the true fungi This group comprises at leastthree major lineages of chytrids (1) Rozella spp the earliestdiverging lineage in kingdom Fungi (2) Olpidium brassicaethe only species classified in Zygomycota and (3) the corechytrid clade encompassing the remaining orders and fam-ilies and most flagellated fungi including those of Chytri-diales Spizellomycetales pp Monoblepharidales andNeocallimastigales (Barr 2001 James et al 2006) Chytridsare unicellular colonial or filamentous organisms with ab-sorptive nutrition and which reproduce through the produc-tion of motile zoospores typically propelled by a singleposteriorly-directed flagellum (Barr 2001)Infection begins with the attachment of a motile

zoospore to the surface of a host cell and the forma-tion of a thickened wall around the zoospore In asuccessful infection the encysted zoospore will de-velop into a mature sporangium following which agerm tube typically forms which enters the host cellvia the girdle zone The zoospores form within thehost cell and are released to infect other cells by de-hiscence The attached zoospores completely dependon the host cell for nourishment and their develop-ment into mature sporangia (Ibelings et al 2004)Traditionally Chytridiomycota have been regarded as

aquatic fungi (Ibelings et al 2004) but most speciesoccur in soil as saprophytes growing on organic material(Digby et al 2010) In addition certain obligate

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 6 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms

Infected insect species Literature data

Oomycota

Aphanomyces laevis Mosquito larvae (Patwardhan et al 2005)

Couchia spp (Wallace Martin 2000)

Crypticola spp (Frances 1991 Dick 2003 Mendoza et al 2018)

Lagenidium giganteum (Golkar et al 1993 Vyas et al 2007 Vilela et al 2019)

Leptolegnia caudata spp (Bisht et al 1996 Montalva et al 2016 Gutierrez et al2017)

Pythium spp (Clark et al 1966 Su et al 2001 Su 2008 Shen et al2019)

Microsporidia

Anncaliia algerae Drosophila melanogaster (Sokolova et al 2020)

Antonospora locustae(Nosema locustae)

Grasshoppers (Lange 2005 Zhou and Zhang 2009 Gerus et al 2020)

Nosema adaliae Two-spotted lady beetle Adalia bipunctata (ColeopteraCoccinellidae)

(Steele and Bjoslashrnson 2014)

Nosema alticae Flea beetle Altica hampei (Coleoptera Chrysomelidae) (Yıldırım and Bekircan 2020)

Nosema bombi Nosemaceranae Tubulinosemapampeana

Bumblebees (Brown 2017)

Nosema carpocapsae Codling moth Cydia pomonella L (Zimmermann et al 2013)

Nosema leptinotarsae Colorado potato beetle Leptinotarsa decemlineata Say(Coleoptera Chrysomelidae)

(Bekircan 2020)

Nosema maddoxi Brown marmorated stink bug Halyomorpha halys (HemipteraPentatomidae)

(Preston et al 2020b Preston et al 2020a)

Nosema pernyi The Chinese oak silkworm Antheraea pernyi (LepidopteraSaturniidae)

(Liu et al 2020)

Nosema pyrausta European corn borer Ostrinia nubilalis the Asian corn borerOstrinia furnacalis and the adzuki bean borer Ostrinia scapulalis

(Grushevaya et al 2018 Grushevaya et al 2020)

TubuliNosema sp Loxostege sticticalis L (Lepidoptera Crambidae) (Malysh et al 2018)

TubuliNosema suzukii Drosophila suzukii (Biganski et al 2020)

Vairimorpha (Nosema)ceranae Vairimorpha(Nosema) apis

Honeybee Apis mellifera (Forsgren and Fries 2010 Tokarev et al 2018Applegate and Petritz 2020 Chang et al 2020Ostroverkhova et al 2020)

Chytridiomycota

Myrmicinosporidiumdurum

Ants from Subfamilies Myrmicinae Formicinae andDolichoderinae

(Sanchez-Pentildea et al 1993 Gonccedilalves et al 2012Trigos-Peral et al 2017)

Nephridiophaga maderaeNephridiophagaarchimandritaNephridiophagalucihormeticaNephridiophaga blattellaeNephridiophaga blaberi

Madeira cockroach (Leucophaea maderae)Archimandrita tessellateLucihormetica verrucoseGerman cockroach Blattella germanicaDeathrsquos head cockroach Blaberus craniifer

(Radek et al 2017)(Radek et al 2011)(Radek and Herth 1999)(Fabel et al 2000)

Blastocladiomycota

Coelomycidium simulii Larval stage of black flies (Diptera) Simulium asakoae Schamlongi S chiangmaiense S fenestratum S feuerborni Snakhonense S nodosum S quinquestriatum S tani and Sjaponicum

(Levchenko et al 1974 Kim 2011 Jitklang et al 2012Kim 2015 Adler and McCreadie 2019)

Coelomomyces africanusCoelomomyces angolensisCoelomomyces iliensisCoelomomyces indicusCoelomomyces iraniCoelomomyces lairdi

Mosquito larvae from species of Culex Culiseta Aedes AnophelesPsorophora and Uranotaenia

(Scholte et al 2004 Balaraman et al 2006 Rueda-Paacuteramo et al 2017 Dahmana and Mediannikov 2020Gao et al 2020)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 4 of 13

The life-cycle of microsporidia is characterized bythree phases an infective or environmental phase(spores) a merogony (proliferative) phase and a sporo-gonic or spore-forming phase (Keeling and Fast 2002)Microsporidia spores are first ingested or inhaled by thehost The spores then germinate and produce a long andconvoluted tubule extrusion apparatus (polar tubule)this tubule distinguishes them from other organisms andplays a crucial role in host cell invasion The spore ap-proaches the host cell and its polar tubule is everted toenter the cell and inject its sporoplasm into the host cellcytoplasm Following successful injection the prolifera-tive phase begins this phase includes all cell growth anddivision from the sporoplasm until spore formation It isknown to include two possible processes schizogonyand merogony Although very little is understood ofschizogony in Oomycota merogony is known to takeplace as the injected sporoplasm develops into meronts(the proliferative stage) these in turn multiply by binaryfission or multiple fission depending on the species toform multinucleate plasmodial forms Finally theseforms undergo sporogony with the meronts developinginto sporonts which produce two or more sporoblaststhese in turn undergo metamorphosis into sporesInterestingly unlike other species in which sporogony

occurs in the presence of plasmalemmal thickening themicrosporidia undergo sporogony to produce diplokar-yotic nuclei after meiosis These sporonts can multiplyby binary or multiple fission acquire specialized organ-elles and become spores Subsequently the spores con-tinue the cycle by spreading through the tissues of thehost infecting new cells (Lallo et al 2016 Han andWeiss 2017 Han et al 2020 Horta et al 2020)Traditionally Microsporidia were classified within the

phylum Apicomplexa as sporozoan parasites howeverphylogenetic studies suggest that microsporidia are relatedto fungi either as a basal branch or sister group (Lee et al2008 Han and Weiss 2017) They have also been found toinclude chitin in the spore wall and use trehalose as a

sugar reserve and studies have noted the presence ofclosed mitosis spindle pole bodies and meiosis (Han andWeiss 2017) Although they can infect a great number ofdomestic and wild animals the most common hosts arearthropods and fish Since their discovery in the 1850s asthe causative agent of the silkworm disease pebrine orpepper disease which devastated the silk industry in Eur-ope these pathogens have demonstrated major economicsignificance in animal farming such as nosemosis in bee-keeping (Nosema aApis and N ceranae) and microspori-diosis in aquaculture (Loma salmonae for salmonids andThelohania spp for shrimp) Nosema bombycis has alsobeen found to infect the domesticated silkworm Bombyxmori In addition some microsporidia act as opportunisticpathogens of humans especially in patients with AIDS(Weiss 2020)About 93 genera of microsporidia have the ability to

infect insects (Becnel and Andreadis 2014) They areconsidered as biological control agents for regulating thepopulation of the beet webworm Loxostege sticticalis re-sponsible for serious damage to crops such as soybeansugar beet alfalfa and sunflower in northern Eurasia(Malysh et al 2020) Interestingly some authors con-sider microsporidia to have enabled the invasive successof the ladybird Harmonia axyridis (Vilcinskas et al2015 Verheggen et al 2017) in which the microsporidiaact as a symbiotic ldquobiological weaponrdquo against somepredators like Coccinella septempunctata and Adaliabipunctata (Ceryngier et al 2018) Some examples of in-fected insects are listed in Table 1Also Antonospora locustae formerly known as No-

sema locustae (syn Paranosema locustae) is commonlyused as a biological control agent for grasshoppers inthe commercial products Nolo Bait and Semaspore(Lange 2005 Zhou and Zhang 2009 Solter et al 2012)Like other microsporidial pathogens A locustae alsoneeds to control the metabolic processes and molecularprogrammes of the host in order to proliferate Success-ful infection was found to suppress the locust gut

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms (Continued)

Infected insect species Literature data

Coelomomyces maclaeyaeCoelomomyces numulariusCoelomomyces opifexCoelomomycespentangulatusCoelomomycespolynesiensisCoelomomyces punctatusCoelomomyces solomonisCoelomomycessantabrancae spp

Myiophagus cf ucrainicus Scale insect Caribbean black scale Saissetia neglecta (Hemiptera)Caliphornia red scale Aonidiella aurantii (Hemiptera)Chironomus atracinus larvae

(Moore and Duncan 2017)(Czeczuga and Godlewska 2001)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 5 of 13

microbiota including the gut bacteria that produce ag-gregation pheromones thus preventing host aggregation(Pan et al 2018)Most microsporidia species require two successive

host generations to complete their life-cycle and at leastthree genera viz Amblyospora Hyalinocysta and Para-thelohania also require development in an intermediatecopepod host (Becnel and Andreadis 2014) These gen-era are also highly host- and tissue-specific with com-plex developmental sequences comprising unique stagesand events (Becnel et al 2005) They are mostly patho-gens of mosquito larvae (Andreadis 1985 Andreadis2007 Shen et al 2020a) interestingly microsporidian in-fection has also been found to be associated with a re-duction in Plasmodium falciparum transmission inAnopheles arabiensis mosquitoes (Herren et al 2020)In contrast some species of microsporidia exhibit sim-

ple life-cycles with a single spore type responsible fororal (horizontal) transmission these affect only one gen-eration of insects and are not usually host or tissue spe-cific (Becnel et al 2005) A good example of a genuswith this simple life-cycle is Nosema including the spe-cies N apis and N ceranae These species are respon-sible for most microsporidian infections in bees andother species of Hymenoptera resulting in ecologicaland economical losses in apiculture (Higes et al 2006Forsgren and Fries 2010 Grupe and Alisha Quandt2020 Ostroverkhova et al 2020 Paudel et al 2020)Interestingly phylogenetic studies have placed the No-sema species able to infect bees within a new genusVairimorpha (Tokarev et al 2020)N apis is believed to have long been a parasite of the

European honeybee Apis mellifera whereas N ceranaeis presumed to have more recently undergone a hostshift to A mellifera from the Asian honeybee A ceranae(Buczek et al 2020 Ostroverkhova et al 2020) The par-asites exhibit a tissue tropism for honey bee ventriculus(Higes et al 2020) and are believed to infect their ven-tricular epithelial cells during digestion infected beessuffer impaired nutrient absorption resulting in energyloss and death by starvation (Valizadeh et al 2020)Nosema pernyi a microsporidium infecting the Chin-

ese oak silkworm Antheraea pernyi can enter the gutcell by polar tube infection in most situations The sporein the polar tube germinates within the alkaline environ-ment of the intestine inducing destructive chronic dis-ease (Wang et al 2019 Han et al 2020) It is alsopossible for the parasite to exploit the metabolism of thehost cell to progress its own life-cycle A recent studyfound that successful infection of the honeybee midgutby the microsporidian pathogen N ceranae involves theinhibition of apoptosis (Higes et al 2013 Kurze et al2018) in such cases the parasite appears to inhibitapoptosis by regulating the genes involved in the

process as well as in the cell cycle (Martiacuten-Hernaacutendezet al 2017) thus increasing oxidative stress and antioxi-dant enzyme generation in the gut and inhibiting thegenes involved in the homeostasis and renewal of intes-tinal tissues (Dussaubat et al 2012 Liu et al 2020)Microsporidial infection can also alter host metabol-

ism and induce both local and systemic innate immuneresponses (Pan et al 2018) For example N ceranae in-fection is believed to suppress immune defence mecha-nisms in honey bees studies have indicated thatinfection downregulates some immune-related genes in-cluding abaecin apidecin defensin hymenoptaecin glu-cose dehydrogenase (GLD) and vitellogenin (Vg) andupregulates Jun-related antigen Jra and pi3k (Changet al 2020) Additionally transcription of the inhibitorof apoptosis protein (iap-2) gene was found to be upreg-ulated in Nosema-tolerant honeybees (Kurze et al 2015)it is possible that inhibition of apoptosis might help theparasites optimize their environment and extend theperiod during which they can grow and differentiatewithin host cells (Higes et al 2013) It also appears thatpheromone production in worker and queen honeybeesto be modified during infection (Dussaubat et al 2013)

CHYTRIDIOMYCOTAThe Chytridiomycota comprise zoosporic fungi phylogenet-ically related to the true fungi This group comprises at leastthree major lineages of chytrids (1) Rozella spp the earliestdiverging lineage in kingdom Fungi (2) Olpidium brassicaethe only species classified in Zygomycota and (3) the corechytrid clade encompassing the remaining orders and fam-ilies and most flagellated fungi including those of Chytri-diales Spizellomycetales pp Monoblepharidales andNeocallimastigales (Barr 2001 James et al 2006) Chytridsare unicellular colonial or filamentous organisms with ab-sorptive nutrition and which reproduce through the produc-tion of motile zoospores typically propelled by a singleposteriorly-directed flagellum (Barr 2001)Infection begins with the attachment of a motile

zoospore to the surface of a host cell and the forma-tion of a thickened wall around the zoospore In asuccessful infection the encysted zoospore will de-velop into a mature sporangium following which agerm tube typically forms which enters the host cellvia the girdle zone The zoospores form within thehost cell and are released to infect other cells by de-hiscence The attached zoospores completely dependon the host cell for nourishment and their develop-ment into mature sporangia (Ibelings et al 2004)Traditionally Chytridiomycota have been regarded as

aquatic fungi (Ibelings et al 2004) but most speciesoccur in soil as saprophytes growing on organic material(Digby et al 2010) In addition certain obligate

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 6 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

The life-cycle of microsporidia is characterized bythree phases an infective or environmental phase(spores) a merogony (proliferative) phase and a sporo-gonic or spore-forming phase (Keeling and Fast 2002)Microsporidia spores are first ingested or inhaled by thehost The spores then germinate and produce a long andconvoluted tubule extrusion apparatus (polar tubule)this tubule distinguishes them from other organisms andplays a crucial role in host cell invasion The spore ap-proaches the host cell and its polar tubule is everted toenter the cell and inject its sporoplasm into the host cellcytoplasm Following successful injection the prolifera-tive phase begins this phase includes all cell growth anddivision from the sporoplasm until spore formation It isknown to include two possible processes schizogonyand merogony Although very little is understood ofschizogony in Oomycota merogony is known to takeplace as the injected sporoplasm develops into meronts(the proliferative stage) these in turn multiply by binaryfission or multiple fission depending on the species toform multinucleate plasmodial forms Finally theseforms undergo sporogony with the meronts developinginto sporonts which produce two or more sporoblaststhese in turn undergo metamorphosis into sporesInterestingly unlike other species in which sporogony

occurs in the presence of plasmalemmal thickening themicrosporidia undergo sporogony to produce diplokar-yotic nuclei after meiosis These sporonts can multiplyby binary or multiple fission acquire specialized organ-elles and become spores Subsequently the spores con-tinue the cycle by spreading through the tissues of thehost infecting new cells (Lallo et al 2016 Han andWeiss 2017 Han et al 2020 Horta et al 2020)Traditionally Microsporidia were classified within the

phylum Apicomplexa as sporozoan parasites howeverphylogenetic studies suggest that microsporidia are relatedto fungi either as a basal branch or sister group (Lee et al2008 Han and Weiss 2017) They have also been found toinclude chitin in the spore wall and use trehalose as a

sugar reserve and studies have noted the presence ofclosed mitosis spindle pole bodies and meiosis (Han andWeiss 2017) Although they can infect a great number ofdomestic and wild animals the most common hosts arearthropods and fish Since their discovery in the 1850s asthe causative agent of the silkworm disease pebrine orpepper disease which devastated the silk industry in Eur-ope these pathogens have demonstrated major economicsignificance in animal farming such as nosemosis in bee-keeping (Nosema aApis and N ceranae) and microspori-diosis in aquaculture (Loma salmonae for salmonids andThelohania spp for shrimp) Nosema bombycis has alsobeen found to infect the domesticated silkworm Bombyxmori In addition some microsporidia act as opportunisticpathogens of humans especially in patients with AIDS(Weiss 2020)About 93 genera of microsporidia have the ability to

infect insects (Becnel and Andreadis 2014) They areconsidered as biological control agents for regulating thepopulation of the beet webworm Loxostege sticticalis re-sponsible for serious damage to crops such as soybeansugar beet alfalfa and sunflower in northern Eurasia(Malysh et al 2020) Interestingly some authors con-sider microsporidia to have enabled the invasive successof the ladybird Harmonia axyridis (Vilcinskas et al2015 Verheggen et al 2017) in which the microsporidiaact as a symbiotic ldquobiological weaponrdquo against somepredators like Coccinella septempunctata and Adaliabipunctata (Ceryngier et al 2018) Some examples of in-fected insects are listed in Table 1Also Antonospora locustae formerly known as No-

sema locustae (syn Paranosema locustae) is commonlyused as a biological control agent for grasshoppers inthe commercial products Nolo Bait and Semaspore(Lange 2005 Zhou and Zhang 2009 Solter et al 2012)Like other microsporidial pathogens A locustae alsoneeds to control the metabolic processes and molecularprogrammes of the host in order to proliferate Success-ful infection was found to suppress the locust gut

Table 1 Examples of insects infected by entomopathogenic fungi and fungal-like organisms (Continued)

Infected insect species Literature data

Coelomomyces maclaeyaeCoelomomyces numulariusCoelomomyces opifexCoelomomycespentangulatusCoelomomycespolynesiensisCoelomomyces punctatusCoelomomyces solomonisCoelomomycessantabrancae spp

Myiophagus cf ucrainicus Scale insect Caribbean black scale Saissetia neglecta (Hemiptera)Caliphornia red scale Aonidiella aurantii (Hemiptera)Chironomus atracinus larvae

(Moore and Duncan 2017)(Czeczuga and Godlewska 2001)

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 5 of 13

microbiota including the gut bacteria that produce ag-gregation pheromones thus preventing host aggregation(Pan et al 2018)Most microsporidia species require two successive

host generations to complete their life-cycle and at leastthree genera viz Amblyospora Hyalinocysta and Para-thelohania also require development in an intermediatecopepod host (Becnel and Andreadis 2014) These gen-era are also highly host- and tissue-specific with com-plex developmental sequences comprising unique stagesand events (Becnel et al 2005) They are mostly patho-gens of mosquito larvae (Andreadis 1985 Andreadis2007 Shen et al 2020a) interestingly microsporidian in-fection has also been found to be associated with a re-duction in Plasmodium falciparum transmission inAnopheles arabiensis mosquitoes (Herren et al 2020)In contrast some species of microsporidia exhibit sim-

ple life-cycles with a single spore type responsible fororal (horizontal) transmission these affect only one gen-eration of insects and are not usually host or tissue spe-cific (Becnel et al 2005) A good example of a genuswith this simple life-cycle is Nosema including the spe-cies N apis and N ceranae These species are respon-sible for most microsporidian infections in bees andother species of Hymenoptera resulting in ecologicaland economical losses in apiculture (Higes et al 2006Forsgren and Fries 2010 Grupe and Alisha Quandt2020 Ostroverkhova et al 2020 Paudel et al 2020)Interestingly phylogenetic studies have placed the No-sema species able to infect bees within a new genusVairimorpha (Tokarev et al 2020)N apis is believed to have long been a parasite of the

European honeybee Apis mellifera whereas N ceranaeis presumed to have more recently undergone a hostshift to A mellifera from the Asian honeybee A ceranae(Buczek et al 2020 Ostroverkhova et al 2020) The par-asites exhibit a tissue tropism for honey bee ventriculus(Higes et al 2020) and are believed to infect their ven-tricular epithelial cells during digestion infected beessuffer impaired nutrient absorption resulting in energyloss and death by starvation (Valizadeh et al 2020)Nosema pernyi a microsporidium infecting the Chin-

ese oak silkworm Antheraea pernyi can enter the gutcell by polar tube infection in most situations The sporein the polar tube germinates within the alkaline environ-ment of the intestine inducing destructive chronic dis-ease (Wang et al 2019 Han et al 2020) It is alsopossible for the parasite to exploit the metabolism of thehost cell to progress its own life-cycle A recent studyfound that successful infection of the honeybee midgutby the microsporidian pathogen N ceranae involves theinhibition of apoptosis (Higes et al 2013 Kurze et al2018) in such cases the parasite appears to inhibitapoptosis by regulating the genes involved in the

process as well as in the cell cycle (Martiacuten-Hernaacutendezet al 2017) thus increasing oxidative stress and antioxi-dant enzyme generation in the gut and inhibiting thegenes involved in the homeostasis and renewal of intes-tinal tissues (Dussaubat et al 2012 Liu et al 2020)Microsporidial infection can also alter host metabol-

ism and induce both local and systemic innate immuneresponses (Pan et al 2018) For example N ceranae in-fection is believed to suppress immune defence mecha-nisms in honey bees studies have indicated thatinfection downregulates some immune-related genes in-cluding abaecin apidecin defensin hymenoptaecin glu-cose dehydrogenase (GLD) and vitellogenin (Vg) andupregulates Jun-related antigen Jra and pi3k (Changet al 2020) Additionally transcription of the inhibitorof apoptosis protein (iap-2) gene was found to be upreg-ulated in Nosema-tolerant honeybees (Kurze et al 2015)it is possible that inhibition of apoptosis might help theparasites optimize their environment and extend theperiod during which they can grow and differentiatewithin host cells (Higes et al 2013) It also appears thatpheromone production in worker and queen honeybeesto be modified during infection (Dussaubat et al 2013)

CHYTRIDIOMYCOTAThe Chytridiomycota comprise zoosporic fungi phylogenet-ically related to the true fungi This group comprises at leastthree major lineages of chytrids (1) Rozella spp the earliestdiverging lineage in kingdom Fungi (2) Olpidium brassicaethe only species classified in Zygomycota and (3) the corechytrid clade encompassing the remaining orders and fam-ilies and most flagellated fungi including those of Chytri-diales Spizellomycetales pp Monoblepharidales andNeocallimastigales (Barr 2001 James et al 2006) Chytridsare unicellular colonial or filamentous organisms with ab-sorptive nutrition and which reproduce through the produc-tion of motile zoospores typically propelled by a singleposteriorly-directed flagellum (Barr 2001)Infection begins with the attachment of a motile

zoospore to the surface of a host cell and the forma-tion of a thickened wall around the zoospore In asuccessful infection the encysted zoospore will de-velop into a mature sporangium following which agerm tube typically forms which enters the host cellvia the girdle zone The zoospores form within thehost cell and are released to infect other cells by de-hiscence The attached zoospores completely dependon the host cell for nourishment and their develop-ment into mature sporangia (Ibelings et al 2004)Traditionally Chytridiomycota have been regarded as

aquatic fungi (Ibelings et al 2004) but most speciesoccur in soil as saprophytes growing on organic material(Digby et al 2010) In addition certain obligate

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 6 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

microbiota including the gut bacteria that produce ag-gregation pheromones thus preventing host aggregation(Pan et al 2018)Most microsporidia species require two successive

host generations to complete their life-cycle and at leastthree genera viz Amblyospora Hyalinocysta and Para-thelohania also require development in an intermediatecopepod host (Becnel and Andreadis 2014) These gen-era are also highly host- and tissue-specific with com-plex developmental sequences comprising unique stagesand events (Becnel et al 2005) They are mostly patho-gens of mosquito larvae (Andreadis 1985 Andreadis2007 Shen et al 2020a) interestingly microsporidian in-fection has also been found to be associated with a re-duction in Plasmodium falciparum transmission inAnopheles arabiensis mosquitoes (Herren et al 2020)In contrast some species of microsporidia exhibit sim-

ple life-cycles with a single spore type responsible fororal (horizontal) transmission these affect only one gen-eration of insects and are not usually host or tissue spe-cific (Becnel et al 2005) A good example of a genuswith this simple life-cycle is Nosema including the spe-cies N apis and N ceranae These species are respon-sible for most microsporidian infections in bees andother species of Hymenoptera resulting in ecologicaland economical losses in apiculture (Higes et al 2006Forsgren and Fries 2010 Grupe and Alisha Quandt2020 Ostroverkhova et al 2020 Paudel et al 2020)Interestingly phylogenetic studies have placed the No-sema species able to infect bees within a new genusVairimorpha (Tokarev et al 2020)N apis is believed to have long been a parasite of the

European honeybee Apis mellifera whereas N ceranaeis presumed to have more recently undergone a hostshift to A mellifera from the Asian honeybee A ceranae(Buczek et al 2020 Ostroverkhova et al 2020) The par-asites exhibit a tissue tropism for honey bee ventriculus(Higes et al 2020) and are believed to infect their ven-tricular epithelial cells during digestion infected beessuffer impaired nutrient absorption resulting in energyloss and death by starvation (Valizadeh et al 2020)Nosema pernyi a microsporidium infecting the Chin-

ese oak silkworm Antheraea pernyi can enter the gutcell by polar tube infection in most situations The sporein the polar tube germinates within the alkaline environ-ment of the intestine inducing destructive chronic dis-ease (Wang et al 2019 Han et al 2020) It is alsopossible for the parasite to exploit the metabolism of thehost cell to progress its own life-cycle A recent studyfound that successful infection of the honeybee midgutby the microsporidian pathogen N ceranae involves theinhibition of apoptosis (Higes et al 2013 Kurze et al2018) in such cases the parasite appears to inhibitapoptosis by regulating the genes involved in the

process as well as in the cell cycle (Martiacuten-Hernaacutendezet al 2017) thus increasing oxidative stress and antioxi-dant enzyme generation in the gut and inhibiting thegenes involved in the homeostasis and renewal of intes-tinal tissues (Dussaubat et al 2012 Liu et al 2020)Microsporidial infection can also alter host metabol-

ism and induce both local and systemic innate immuneresponses (Pan et al 2018) For example N ceranae in-fection is believed to suppress immune defence mecha-nisms in honey bees studies have indicated thatinfection downregulates some immune-related genes in-cluding abaecin apidecin defensin hymenoptaecin glu-cose dehydrogenase (GLD) and vitellogenin (Vg) andupregulates Jun-related antigen Jra and pi3k (Changet al 2020) Additionally transcription of the inhibitorof apoptosis protein (iap-2) gene was found to be upreg-ulated in Nosema-tolerant honeybees (Kurze et al 2015)it is possible that inhibition of apoptosis might help theparasites optimize their environment and extend theperiod during which they can grow and differentiatewithin host cells (Higes et al 2013) It also appears thatpheromone production in worker and queen honeybeesto be modified during infection (Dussaubat et al 2013)

CHYTRIDIOMYCOTAThe Chytridiomycota comprise zoosporic fungi phylogenet-ically related to the true fungi This group comprises at leastthree major lineages of chytrids (1) Rozella spp the earliestdiverging lineage in kingdom Fungi (2) Olpidium brassicaethe only species classified in Zygomycota and (3) the corechytrid clade encompassing the remaining orders and fam-ilies and most flagellated fungi including those of Chytri-diales Spizellomycetales pp Monoblepharidales andNeocallimastigales (Barr 2001 James et al 2006) Chytridsare unicellular colonial or filamentous organisms with ab-sorptive nutrition and which reproduce through the produc-tion of motile zoospores typically propelled by a singleposteriorly-directed flagellum (Barr 2001)Infection begins with the attachment of a motile

zoospore to the surface of a host cell and the forma-tion of a thickened wall around the zoospore In asuccessful infection the encysted zoospore will de-velop into a mature sporangium following which agerm tube typically forms which enters the host cellvia the girdle zone The zoospores form within thehost cell and are released to infect other cells by de-hiscence The attached zoospores completely dependon the host cell for nourishment and their develop-ment into mature sporangia (Ibelings et al 2004)Traditionally Chytridiomycota have been regarded as

aquatic fungi (Ibelings et al 2004) but most speciesoccur in soil as saprophytes growing on organic material(Digby et al 2010) In addition certain obligate

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 6 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

anaerobic species also occur in the digestive tract of her-bivores and these are probably very important in the di-gestion of cellulose and hemicellulose (Li and Heath1993 Paul et al 2018 Saye et al 2021) A few halophyteshave been found in estuaries (Powell et al 2015) A sig-nificant number of species are known as parasites ofalgae vascular plants amphibians rotifers tardigradesprotists (Luttrell 1974 Barr 2001 Ibelings et al 2004)and invertebrates such as nematodes (Betancourt-Romaacutenet al 2016) and insects (Sinha et al 2016) The first de-scribed parasites of vertebrates were isolated from frogskin (Longcore et al 1999)The chytrids include one entomopathogenic genus

the monotypic Myrmicinosporidium (M durum) Thatspecies is an obligate endoparasite of various ant hostswith a global or wide-ranging specific distribution(Lapeva-Gjonova 2014 Trigos-Peral et al 2017) Infectedants can be distinguished by their darker colour and lar-ger abdomen size Although the numbers of lentiformspores within an infected ant may initially be very lowthey increase during infection to the point where theycan be found throughout the whole body numberingmore than one hundred in a single ant (Sanchez-Pentildeaet al 1993 Pereira 2004 Espadaler and Santamaria2012 Gonccedilalves et al 2012) Although the spores de-velop extensively in the ant haemocoel an infected antdoes not exhibit significant differences in life span or be-haviour from uninfected ones (Sanchez-Pentildea et al1993) however several studies have reported the earlydeath of infected ants after hibernation (Espadaler andSantamaria 2012 Giehr and Heinze 2015) Some exam-ples infected of insects are listed in Table 1Recent studies have also placed the nephridiophagids

in Chytridiomycota (Strassert et al 2020) The systematicposition of the nephridiophagids has been discussed in-tensively and they were historically placed with the hap-losporidians or microsporidians (Radek et al 2017) Apreliminary molecular analysis placed them within theFungi close to the Zygomycota (Wylezich C Radek R2004) however a later phylogenetic analysis of SSU andLSU rRNA gene sequences placed them in the phylumChytridiomycota (Strassert et al 2020)Nephridiophagids are unicellular spore-forming para-

sites which infect the Malpighian tubules of insects es-pecially cockroaches (Dictyoptera) and beetles(Coleoptera) where they are mainly found in the lumen(Radek et al 2011) The life-cycle of the nephridiopha-gids includes a merogony phase with vegetative multinu-cleate plasmodia that divide into oligonucleate anduninucleate cells The sporogonial plasmodia form in-ternal 5ndash10 μm long oval flattened spores generallywith one nucleus with the residual nuclei of the mothercell remaining in the cytoplasm between them (Radeket al 2017)

BLASTOCLADIOMYCOTAHistorically the fungi belonging to the phylum Blasto-cladiomycota were described together with the Chytri-diomycota however recent molecular phylogenetic andultrastructural research has classified them in their ownphylum (James et al 2006 Porter et al 2011) Genome-scale trees suggest Blastocladiomycota may have di-verged around the same time as Chytridiomycota (Jameset al 2020)The Blastocladiomycota contains only the order Blas-

tocladiales this group contains zoospore-producing truefungi with well-developed hyphae closed mitosis cellwalls with β-1ndash3-glucan and a secretory vesicle complexknown as the Spitzenkoumlrper (James et al 2020 Roberson2020) Several of these were once model organisms (egAllomyces and Blastocladiella (Cantino et al 1968Burke et al 1972) and obligate parasites of plants andanimals (Longcore and Simmons 2012) They are dividedinto five families (Barr 2001) Blastocladiaceae whichcontains only saprobic species Catenariaceae with bothsaprobes and pathogens Coelomomycetaceae with path-ogens of invertebrates Physodermataceae with obligateparasites of plants and Sorochytriaceae which contains apathogen infecting tardigrades Powell (2017) subse-quently described a sixth family Paraphysodermataceaewhich includes parasites of algaeThe entomopathogenic Blastocladiomycota are found in

the genera Coelomomyces and Coelomycidium of Coelo-momycetaceae These genera include approximately 70species pathogenic to insects such as mosquitoes and flies(Powell 2017 Shen et al 2020a) Some examples of insectsinfected by Blastocladiomycota are listed in Table 1Coelomycidium simulii is a widespread species patho-

genic to black flies being mostly found in the larvaeand rarely in pupae and adults Infected larvae have largenumbers of minute spherical thalli throughout the bodycavity These thalli give rise to spores that are releasedinto the water column after the death of the host Anintermediate host might be required to complete thelife-cycle (McCreadie and Adler 1999 Boucias andPendland 2012)The species of Coelomomyces are aquatic fungi that

act as obligate parasites They are best known as patho-gens of mosquito larvae however some might infectaquatic dipteran insects including those of the Psychodi-dae Chironomidae Simuliidae and Tabanidae (Scholteet al 2004 Shen et al 2020a) Although they are prob-ably not host specific they nevertheless have relativelyrestricted host ranges (Federici 1981) The life-cycle ofCoelomomyces is complex and comprises obligatory de-velopment in an intermediate microcrustacean host(cyclopoid copepods harpacticoid copepods or ostra-cods) and two mosquito generations Infection is alsoknown to cause significant epizootics which can persist

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 7 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

in larval populations for several years resulting in mor-tality rates greater than 50 and often higher than 90(Scholte et al 2004) Moreover the fungus might remaininside the insect passing through the larval and pupalstages to mature in the ovaries of adult females wherethe sporangia start to produce zoospores After the firstblood meal these zoospore-filled sporangia are lsquolaidrsquo bythe female mosquito ready to infect new larvae insteadof eggs (Arauacutejo and Hughes 2016) Due to the relativelyspecific host range of the fungus being generally re-stricted to mosquitoes and the devastating effects ofnatural epizootics on larval populations it has been pro-posed as a suitable biocontrol of mosquito populationsHowever these advantages have to be weighed againstits unpredictable infection rate complicated life-cycleand problem with mass production (Scholte et al 2004)The fungi placed in Myiophagus were initially con-

sidered to belong to Chytridiomycota (Blackwell andPowell 2020) however based on their morphologicaldifferences they are now placed in Blastocladiomycota(Humber 2012 James et al 2014 Powell 2017) Spe-cies of this genus infect leeches (Czeczuga et al2003) scale insects mealybugs beetle larvae and dip-teran pupae (Karling 1948) resulting in chytridiosis insubtropical regions (Tanada and Kaya 2012) As Myio-phagus requires free water for dissemination (Cole2012) infection takes place shortly after or duringheavy rainfall In such conditions motile zoosporesare released from resting sporangia and these swimthrough the water film that forms over ldquodrip leavesrdquoto find potential hosts similar to other aquatic fungithe zoospores are believed to be guided to the hostby specific chemoreceptors (Luisa 2012)

CONCLUSIONBiological control is an effective and environmentally-acceptable alternative to chemical insect controlmethods Entomopathogenic fungi and their metabo-lites are believed to represent potential alternatives tochemical pesticides When used as biocontrol agentsentomopathogens might offer several advantages overconventional insecticides such as high efficiency andselectivity safety for beneficial organisms reductionof residues in the environment and increased bio-diversity in human-managed ecosystems Howeverrelatively little is known of their effectiveness in fieldapplications and the potential side effects of their useIt is also important to emphasise that due to the glo-bal distribution and variety of insects many as yetunknown entomopathogenic fungi may exist as suchthere is a clear need for further comprehensive stud-ies of the biology and ecology of entomopathogenicorganisms and of the mechanisms underlying theiraction on insect hosts

AcknowledgementsNot applicable

Adherence to national and international regulationsNot applicable

Authorsrsquo contributionsAK ndash Conceptualization Writing ndash original draft MIB - Writing ndash review ampediting The authors read and approved the final manuscript

FundingNot applicable

Availability of data and materialsNot applicable

Declarations

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests

Author details1Witold Stefański Institute of Parasitology Polish Academy of SciencesTwarda 5155 00-818 Warsaw Poland 2Biomibo Strzygłowska 15 04-872Warsaw Poland

Received 13 January 2021 Accepted 25 July 2021

ReferencesAdler PH McCreadie JW Black Flies (Simuliidae) In Medical and Veterinary

Entomology 3rd ed Mullen GR Durden LA Eds Elsevier Inc AmsterdamThe Netherlands 2019 pp 237ndash259

Andreadis TG (1985) Life cycle epizootiology and horizontal transmission ofAmblyospora (Microspora Amblyosporidae) in a univoltine mosquito Aedesstimulans Journal of Invertebrate Pathology 4631ndash46 httpsdoiorg1010160022-2011(85)90127-2

Andreadis TG (2007) Microsporidian parasites of mosquitoes Journal of theAmerican Mosquito Control Association 233ndash29 httpsdoiorg1029878756-971x

Antuacutenez K Martiacuten-Hernaacutendez R Prieto L Meana A Zunino P Higes M (2009)Immune suppression in the honey bee (Apis mellifera) following infection byNosema ceranae (microsporidia) Environmental Microbiology 112284ndash2290httpsdoiorg101111j1462-2920200901953x

Applegate JR Petritz OA (2020) Common and emerging infectious diseases ofhoneybees (Apis mellifera) The Veterinary Clinics of North America ExoticAnimal Practice 23285ndash297 httpsdoiorg101016jcvex202001001

Arauacutejo JPM Hughes DP (2016) Diversity of entomopathogenic fungi Whichgroups conquered the insect body In Lovett B St Leger RJ (eds) advancesin genetics Academic press pp 1ndash39

Balaraman K Vijayan V Geetha I (2006) Biodiversity of mosquitocidal fungi andActinomycetes Biodivers Life to our mother earth 355ndash370

Barr DJS (2001) Chytridiomycota In McLaughlin DJ McLaughlin EG Lemke PA(eds) Systematics and evolution Springer Berlin Heidelberg BerlinHeidelberg pp 93ndash112

Beakes GW Glockling SL Sekimoto S (2012) The evolutionary phylogeny of theoomycete lsquofungirsquo Protoplasma 2493ndash19 httpsdoiorg101007s00709-011-0269-2

Beakes GW Thines M (2017) Hyphochytriomycota and Oomycota In ArchibaldJM Simpson AGB Slamovits CH (eds) Handbook of the Protists Second ednSpringer International Publishing Cham pp 435ndash505

Becnel JJ Andreadis TG (2014) Microsporidia in insects In microsporidiapathogens of opportunity first edition Pp 521ndash570

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 8 of 13

Becnel JJ White SE Shapiro AM (2005) Review of microsporidia-mosquitorelationships from the simple to the complex Folia Parasitologica (Praha) 5241ndash50 httpsdoiorg1014411fp2005006

Bekircan Ccedil (2020) Assignment of Vairimorpha leptinotarsae comb nov on thebasis of molecular characterization of Nosema leptinotarsae Lipa 1968(microsporidia Nosematidae) Parasitology 1471019ndash1025 httpsdoiorg101017S0031182020000669

Betancourt-Romaacuten CM OrsquoNeil CC James TY (2016) Rethinking the role ofinvertebrate hosts in the life cycle of the amphibian chytridiomycosis pathogenParasitology 143(13)1723ndash1729 httpsdoiorg101017S0031182016001360

Biganski S Wennmann JT Vossbrinck CR Kaur R Jehle JA Kleespies RG (2020)Molecular and morphological characterisation of a novel microsporidianspecies Tubulinosema suzukii infecting Drosophila suzukii (DipteraDrosophilidae) Journal of Invertebrate Pathology 174 httpsdoiorg101016jjip2020107440

Bisht GS Joshi C Khulbe RD (1996) Watermolds potential biological controlagents of malaria vector anopheles culicifacies Current Science 70393ndash395

Blackwell M (2010) Fungal evolution and taxonomy BioControl 55(1)7ndash16httpsdoiorg101007s10526-009-9243-8

Blackwell WH Powell MJ (2020) A nomenclatural and systematic note on thegenus Myiophagus (ex Chytridiomycota) Phytologia 1025ndash8

Boucias DG Pendland JC (2012) Principles of insect pathology Springer USBrown MJF (2017) Microsporidia an emerging threat to bumblebees Trends in

Parasitology 33754ndash762 httpsdoiorg101016jpt201706001Buczek K Trytek M Deryło K Borsuk G Rybicka-Jasińska K Gryko D Cytryńska M

Tchoacuterzewski M (2020) Bioactivity studies of porphyrinoids againstmicrosporidia isolated from honeybees Scientific Reports 10 httpsdoiorg101038s41598-020-68420-5

Burke DJ Seale TW McCarthy BJ (1972) Protein and ribonucleic acid synthesisduring the diploid life cycle of Allomyces arbuscula Journal of Bacteriology1101065ndash1072 httpsdoiorg101128jb11031065-10721972

Cantino EC Truesdell LC Shaw DS (1968) Life history of the motile spore ofBlastocladiella emersonii a study in cell differentiation Journal of the ElishaMitchell Scientific Society 84125ndash146

Ceryngier P Nedvěd O Grez AA Riddick EW Roy HE San Martin G Steenberg TVeselyacute P Zaviezo T Zuacutentildeiga-Reinoso Aacute Haelewaters D (2018) Predators andparasitoids of the harlequin ladybird Harmonia axyridis in its native rangeand invaded areas Biological Invasions 201009ndash1031 httpsdoiorg101007s10530-017-1608-9

Chang ZT Ko CY Yen MR Chen YW Nai YS (2020) Screening of differentiallyexpressed microsporidia genes from Nosema ceranae infected honey beesby suppression subtractive hybridization Insects httpsdoiorg103390insects11030199

Clark TB Kellen WR Lindegren JE Sanders RD (1966) Pythium sp (PhycomycetesPythiales) pathogenic to mosquito larvae Journal of Invertebrate Pathology8(3)351ndash354 httpsdoiorg1010160022-2011(66)90049-8

Cole GT (2012) Biology of conidial fungi Elsevier ScienceCorradi N (2015) Microsporidia eukaryotic intracellular parasites shaped by gene

loss and horizontal gene transfers Annual Review of Microbiology 69167ndash183 httpsdoiorg101146annurev-micro-091014-104136

Corradi N Keeling PJ (2009) Microsporidia a journey through radical taxonomicalrevisions Fungal Biology Reviews 231ndash8

Czeczuga B Godlewska A (2001) Aquatic insects as vectors of aquatic zoosporicfungi parasitic on fishes Acta Ichthyologica et Piscatoriat 31(2)87ndash104httpsdoiorg103750AIP200131207

Czeczuga B Kiziewicz B Godlewska A (2003) Zoosporic fungi growing on leeches(Hirudinea) Polish Journal of Environmental Studies 12361ndash369

Dahmana H Mediannikov O (2020) Mosquito-borne diseases emergenceresurgence and how to effectively control it biologically Pathogens 9310httpsdoiorg103390pathogens9040310

Dick M W (2001) Straminipilous fungi Systematics of the peronosporomycetesincluding accounts of the marine straminipilous protists the plasmodiophoridsand similar organisms Dordrecht Kluwer Academic Publishers

Digby AL Gleason FH McGee PA (2010) Some fungi in the Chytridiomycota canassimilate both inorganic and organic sources of nitrogen Fungal Ecology 3261ndash266 httpsdoiorg101016jfuneco200911002

Dobrowolski JW Bedla D Czech T Gambuś F Goacuterecka K Kiszczak W Kuźniar TMazur R Nowak A Śliwka M Tursunov O Wagner A Wieczorek JZabochnicka-Światek M (2018) Integrated innovative biotechnology foroptimization of environmental bioprocesses and a green economyOptimization and Applicability of Bioprocesses In pp 27ndash71

Dowd PF Johnson ET Pinkerton TS (2007) Oral toxicity of β-N-acetylhexosaminidase to insects Journal of Agricultural and Food Chemistr 553421ndash3428 httpsdoiorg101021jf063562w

Dussaubat C Brunet JL Higes M Colbourne JK Lopez J Choi JH Martiacuten-Hernaacutendez R Botiacuteas C Cousin M McDonnell C Bonnet M Belzunces LPMoritz RFA Le Conte Y Alaux C (2012) Gut pathology and responses to themicrosporidium Nosema ceranae in the honey bee Apis mellifera PLoS One 7httpsdoiorg101371journalpone0037017

Dussaubat C Maisonnasse A Crauser D Beslay D Costagliola G Soubeyrand SKretzchmar A Le Conte Y (2013) Flight behavior and pheromone changesassociated to Nosema ceranae infection of honey bee workers (Apis mellifera)in field conditions Journal of Invertebrate Pathology 113(1)42ndash51 httpsdoiorg101016jjip201301002

Espadaler X Santamaria S (2012) Ecto- and endoparasitic fungi on ants from theHolarctic region Psyche (London) 20121ndash10 httpsdoiorg1011552012168478

Fabel P Radek R Storch V (2000) A new spore-forming protist Nephridiophagablaberi sp nov in the Deathrsquos head cockroach Blaberus craniifer EuropeanJournal of Protistology 36387ndash395 httpsdoiorg101016S0932-4739(00)80044-9

Federici B (1981) Mosquito control by the fungi Culicinomyces Lagenidium andCoelomomyces Microbial control of pests and plant diseases 1970-1980 v1981555ndash572

Forsgren E Fries I (2010) Comparative virulence of Nosema ceranae and Nosemaapis in individual European honey bees Veterinary Parasitology 170212ndash217httpsdoiorg101016jvetpar201002010

Frances SP (1991) Pathogenicity host range and temperature tolerance ofCrypticola clavulifera (oomycetes Lagenidiales) in the laboratory Journal ofthe American Mosquito Control Association 7504ndash506

Frances SP Sweeney AW Humber RA (1989) Crypticola clavulifera gen Et sp novand Lagenidium giganteum oomycetes pathogenic for dipterans infestingleaf axils in an Australian rain forest Journal of Invertebrate Pathology 54103ndash111 httpsdoiorg1010160022-2011(89)90146-8

Gani M Hassan T Saini P Gupta RK Bali K (2019) Molecular phylogeny ofEntomopathogens In Khan M Ahmad W (eds) Microbes forsustainable insect Pest management Sustainability in Plant and CropProtection Springer Cham pp 43ndash113 httpsdoiorg101007978-3-030-23045-6_3

Gao H Cui C Wang L Jacobs-Lorena M Wang S (2020) Mosquito microbiota andimplications for disease control Trends in Parasitology 3698ndash111 httpsdoiorg101016jpt201912001

Garciacutea-Palencia P Martiacuten-Hernaacutendez R Gonzaacutelez-Porto AV Marin P Meana AHiges M (2010) Natural infection by Nosema ceranae causes similarlesions as in experimentally infected caged-worker honey bees (Apismellifera) Journal of Apicultural Research 49(3)278ndash283 httpsdoiorg103896IBRA149308

Gerus A Ignatieva A Tokarev У (2020) Prevalence rates of microsporidia inlocusts and grasshoppers in South-Western Russia BIO Web of Conferences2100010 httpsdoiorg101051bioconf20202100010

Giehr J Heinze J Schrempf A (2015) The Ant Cardiocondyla elegans as Host ofthe Enigmatic Endoparasitic Fungus Myrmicinosporidium durum Psyche AJournal of Entomology 20154 Article ID 364967 httpsdoiorg1011552015364967

Golkar L Lebrun RA Ohayon H Gounon P Papierok B Brey PT (1993) Variation oflarval susceptibility to Lagenidium giganteum in three mosquito species Journalof Invertebrate Pathology 621ndash8 httpsdoiorg101006jipa19931066

Gonccedilalves C Patanita I Espadaler X (2012) Substantial and significant expansionof ant hosts range for Myrmicinosporidium houmllldobler 1933 (fungi) InsectesSociaux 59(3)395ndash399 httpsdoiorg101007s00040-012-0232-z

Grupe AC Alisha Quandt C (2020) A growing pandemic a review of Nosemaparasites in globally distributed domesticated and native bees PLoSPathogens 16(6)16 httpsdoiorg101371journalppat1008580

Grushevaya I Ignatieva A Tokarev Y (2020) Susceptibility of three species of thegenus Ostrinia (Lepidoptera Crambidae) to Nosema pyrausta (microsporidiaNosematida) BIO Web of Conferences 2100040 httpsdoiorg101051bioconf20202100040

Grushevaya IV Ignatieva AN Malysh SM Senderskiy IV Zubarev IV KononchukAG (2018) Spore dimorphism in Nosema pyrausta (microsporidiaNosematidae) from morphological evidence to molecular geneticverification Acta Protozoologica 5749ndash52 httpsdoiorg10446716890027AP180048398

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 9 of 13

Gutierrez AC Rueda Paacuteramo ME Falvo ML Loacutepez Lastra CC Garciacutea JJ (2017)Leptolegnia chapmanii (Straminipila Peronosporomycetes) as a futurebiorational tool for the control of Aedes aegypti (L) Acta Tropica 169112ndash118 httpsdoiorg101016jactatropica201701021

Haag KL James TY Pombert JF Larsson R Schaer TMM Refardt D Ebert D (2014)Evolution of a morphological novelty occurred before genome compactionin a lineage of extreme parasites Proceedings of the National Academy ofSciences of the United States of America 11115480ndash15485 httpsdoiorg101073pnas1410442111

Haag KL Pombert JF Sun Y De Albuquerque NRM Batliner B Fields P Lopes TFEbert D (2019) Microsporidia with vertical transmission were likely shaped bynonadaptive processes Genome Biology and Evolution 123599ndash3614httpsdoiorg101093gbeevz270

Hallmon CF Schreiber ET Vo T Bloomquist MA (2000) Field trials of threeconcentrations of Laginextrade as biological larvicide compared to Vectobactrade-12as as a biocontrol agent for Culex quinquefasciatus Journal of theAmerican Mosquito Control Association 165ndash8

Han B Takvorian PM Weiss LM (2020) Invasion of host cells by microsporidiaFrontiers in Microbiology 11 httpsdoiorg103389fmicb202000172

Han B Weiss LM (2017) Microsporidia obligate intracellular pathogens within thefungal kingdom Microbiology Spectrum5 httpsdoiorg101128microbiolspecfunk-0018-2016

Hassett BT Thines M Buaya A Ploch S Gradinger R (2019) A glimpse intothe biogeography seasonality and ecological functions of arcticmarine Oomycota IMA Fungus 10 httpsdoiorg101186s43008-019-0006-6

Herren JK Mbaisi L Mararo E et al A microsporidian impairs Plasmodiumfalciparum transmission in Anopheles arabiensis mosquitoes NatCommun11 2187 (2020) httpsdoiorg101038s41467-020-16121-y

Higes M Garciacutea-Palencia P Martiacuten-Hernaacutendez R Meana A (2007) Experimental infection ofApis mellifera honeybees with Nosema ceranae (microsporidia) Journal of InvertebratePathology 94(3)211ndash217 httpsdoiorg101016jjip200611001

Higes M Garciacutea-Palencia P Urbieta A Nanetti A Martiacuten-Hernaacutendez R (2020)Nosema Apis and Nosema ceranae tissue tropism in worker honey bees (Apismellifera) Veterinary Pathology 57132ndash138 httpsdoiorg1011770300985819864302

Higes M Juarranz Aacute Dias-Almeida J Lucena S Botiacuteas C Meana A Garciacutea-PalenciaP Martiacuten-Hernaacutendez R (2013) Apoptosis in the pathogenesis of Nosemaceranae (microsporidia Nosematidae) in honey bees (Apis mellifera)Environmental Microbiology Rep 5(4)530ndash536 httpsdoiorg1011111758-222912059

Higes M Martiacuten R Meana A (2006) Nosema ceranae a new microsporidianparasite in honeybees in Europe Journal of Invertebrate Pathology 9293ndash95httpsdoiorg101016jjip200602005

Horta MF Andrade LO Martins-Duarte EacuteS Castro-Gomes T (2020) Cell invasion byintracellular parasites - the many roads to infection Journal of Cell Science133(4) httpsdoiorg101242jcs232488

Humber RA (2008) Evolution of entomopathogenicity in fungi Journal ofInvertebrate Pathology 98262ndash266 httpsdoiorg101016jjip200802017

Humber RA (2012) Identification of entomopathogenic fungi Manual ofTechniques in Invertebrate Pathology In

Ibelings BW De Bruin A Kagami M Rijkeboer M Brehm M Van Donk E (2004)Host parasite interactions between freshwater phytoplankton and chytridfungi (Chytridiomycota) Journal of Phycology 40(3)437ndash453 httpsdoiorg101111j1529-8817200403117x

James TY Letcher PM Longcore JE Mozley-Standridge SE Porter D PowellMJ Griffith GW Vilgalys R (2006) A molecular phylogeny of theflagellated fungi (Chytridiomycota) and description of a new phylum(Blastocladiomycota) Mycologia 98(6)860ndash871 httpsdoiorg103852mycologia986860

James TY Porter TM Martin WW (2014) 7 Blastocladiomycota In McLaughlin DJSpatafora JW (eds) Systematics and evolution part a Springer BerlinHeidelberg Berlin Heidelberg pp 177ndash207

James TY Stajich JE Hittinger CT Rokas A (2020) Toward a fully resolved fungaltree of life Annual Review of Microbiology 74(1)291ndash313 httpsdoiorg101146annurev-micro-022020-051835

Aronski S Mascarin GM 2016 Mass production of fungal entomopathogens InLacey LA editor Microbial Control of Insect and Mite Pests from Theory toPractice Yakima WA IP Consulting International p 141-155 httpsdoiorg101016B978-0-12-803527-600009-3

Jitklang S Ahantarig A Kuvangkadilok C Baimai V Adler PH (2012) Parasites oflarval black flies (Diptera Simuliidae) in Thailand Songklanakarin Journal ofScience and Technology 34597ndash599

Joop G Vilcinskas A Coevolution of parasitic fungi and insect hosts Zoology(Jena) 2016 Aug119(4)350-8 httpsdoiorg101016jzool201606005

Kamoun S Furzer O Jones JDG Judelson HS Ali GS Dalio RJD Roy SG Schena LZambounis A Panabiegraveres F Cahill D Ruocco M Figueiredo A Chen XRHulvey J Stam R Lamour K Gijzen M Tyler BM Gruumlnwald NJ Mukhtar MSTomeacute DFA Toumlr M Van Den Ackerveken G Mcdowell J Daayf F Fry WELindqvist-Kreuze H Meijer HJG Petre B Ristaino J Yoshida K Birch PRJGovers F (2015) The top 10 oomycete pathogens in molecular plantpathology Molecular Plant Pathology 16(4)413ndash434 httpsdoiorg101111mpp12190

Karaboumlrkluuml S Azizoglu U amp Azizoglu ZB Recombinant entomopathogenicagents a review of biotechnological approaches to pest insect control WorldJ Microbiol Biotechnol34 14 (2018) httpsdoiorg101007s11274-017-2397-0

Karling JS (1948) Chytridiosis of scale insects American Journal of Botany 35246httpsdoiorg1023072437955

Karlovsky P Fartmann B (1992) Genetic code and phylogenetic origin ofoomycetous mitochondria Journal of Molecular Evolution 34(3)254ndash258httpsdoiorg101007BF00162974

Kaur R Stoldt M Jongepier E Feldmeyer B Menzel F Bornberg-Bauer E Foitzik S(2019) Ant behaviour and brain gene expression of defending hosts dependon the ecological success of the intruding social parasite PhilosophicalTransactions of the Royal Society B Biological Sciences 1374(1769)20180192httpsdoiorg101098rstb20180192

Keeling P (2009) Five questions about microsporidia PLoS Pathogens 5(9)e1000489 httpsdoiorg101371journalppat1000489

Keeling PJ Fast NM (2002) Microsporidia biology and evolution of highlyreduced intracellular parasites Annual Review of Microbiology 56(1)93ndash116httpsdoiorg101146annurevmicro56012302160854

Kepler RM Sung GH Harada Y Tanaka K Tanaka E Hosoya T Bischoff JFSpatafora JW (2012) Host jumping onto close relatives and across kingdomsby Tyrannicordyceps (Clavicipitaceae) gen Nov and Ustilaginoidea(Clavicipitaceae) American Journal of Botany 99552ndash561 httpsdoiorg103732ajb1100124

Kim KH Kabir E Jahan SA (2017) Exposure to pesticides and the associatedhuman health effects Science of the Total Environment 575525ndash535 httpsdoiorg101016jscitotenv201609009

Kim SK (2011) Redescription of Simulium (Simulium) japonicum (Diptera Simuliiae)and its entomopathogenic fungal symbionts Entomological Research 41(5)208ndash210 httpsdoiorg101111j1748-5967201100336x

Kim S-K (2015) Morphology and ecological notes on the larvae and pupae ofSimulium (Simulium) from Korea Animal Systematics Evolution and Diversity31(4)209ndash246 httpsdoiorg105635ased2015314209

Klinter S Bulone V Arvestad L Diversity and evolution of chitin synthases inoomycetes (Straminipila Oomycota) Mol Phylogenet Evol 2019 Oct139106558 httpsdoiorg101016jympev2019106558

Kurze C Le Conte Y Dussaubat C Erler S Kryger P Lewkowski O et al(2015) Nosema Tolerant Honeybees (Apis mellifera) Escape ParasiticManipulation of Apoptosis PLoS ONE 10(10)e0140174 httpsdoiorg101371journalpone0140174

Kurze C Le Conte Y Kryger P Lewkowski O Muumlller T Moritz RFA (2018) Infectiondynamics of Nosema ceranae in honey bee midgut and host cell apoptosisJournal of Invertebrate Pathology 1541ndash4 httpsdoiorg101016jjip201803008

Lacey LA (2017) Entomopathogens Used as Microbial Control Agents httpsdoiorg101016B978-0-12-803527-600001-9

Lacey LA Frutos R Kaya HK Vail P (2001) Insect pathogens as biological controlagents do they have a future Biological Control 21230ndash248 httpsdoiorg101006bcon20010938

Lacey LA Grzywacz D Shapiro-Ilan DI Frutos R Brownbridge M Goettel MS(2015) Insect pathogens as biological control agents Back to the futureJournal of Invertebrate Pathology 1321ndash41 httpsdoiorg101016jjip201507009

Lallo MA Vidoto Da Costa LF Alvares-Saraiva AM et al Culture and propagationof microsporidia of veterinary interest The Journal of Veterinary MedicalScience 78(2)171-176 httpsdoiorg101292jvms15gt

Lange CE (2005) The host and geographical range of the grasshopper pathogenParanosema (Nosema) locustae revisited Journal of Orthoptera Research 14(2)137ndash141 httpsdoiorg1016651082-6467(2005)14[137THAGRO]20CO2

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 10 of 13

Lapeva-Gjonova A (2014) Cataglyphis aenescens - a newly discovered ant host ofthe fungal parasite Myrmicinosporidium durum Bulgarian Journal ofAgricultural Science 20157ndash159

Lee SC Corradi N Byrnes EJ Torres-Martinez S Dietrich FS Keeling PJ Heitman J(2008) Microsporidia evolved from ancestral sexual fungi Current Biology18(21)1675ndash1679 httpsdoiorg101016jcub200809030

Leoro-Garzon P Gonedes AJ Olivera IE (2019) Tartar a (2019) oomycetemetabarcoding reveals the presence of Lagenidium spp In phytotelmataPeerJ httpsdoiorg107717peerj7903

Levchenko NG Dubitskii AM Vakker VG (1974) Enteropathogenic fungusCoelomycidium simulii (Phycomycetes Chitridiales) in the larva of black fliesof the genus Odagmia (Diptera Simuliidae) in Kazakhstan MeditsinskayaParazitologiya i Parazitarnye Bolezni (Mosk) 43110ndash112

Li J Heath IB (1993) Chytridiomycetous gut fungi oft overlooked contributors toherbivore digestion Canadian Journal of Microbiology 39(11)1003ndash1013httpsdoiorg101139m93-153

Litwin A Nowak M Roacuteżalska S (2020) Entomopathogenic fungi unconventionalapplications Reviews in Environmental Science and BioTechnology 19(1)23ndash42 httpsdoiorg101007s11157-020-09525-1

Liu W Wang Y Leng Z Wang Q Duan X Luo Y Jiang Y Qin L (2020) Nitric oxideplays a crucial role in midgut immunity under microsporidian infection inAntheraea pernyi Molecular Immunology 12665ndash72 httpsdoiorg101016jmolimm202007018

Longcore JE Pessier AP Nichols DK (1999) Batrachochytrium dendrobatidis gen Etsp nov a chytrid pathogenic to amphibians Mycologia 91(2)219ndash227httpsdoiorg1023073761366

Longcore JE Simmons DR 2012 Blastocladiomycota (8 pp) In Encyclopedia ofLife Sciences John Wiley amp Sons Ltd Chichester wwwelsnet httpdxdoiorg1010029780470015902a0000349pub3

Luisa BG (2012) Insect-fungus interactions Academic PressLuttrell ES (1974) Parasitism of fungi on vascular plants Mycologia 661ndash15

httpsdoiorg10108000275514197412019567Malysh J Tokarev Y Malysh S Xingfu J Frolov A (2020) Biodiversity of beet

webworm microsporidia in Eurasia In BIO Web of Conferences p 00019Malysh JM Ignatieva AN Artokhin KS Frolov AN Tokarev YS (2018) Natural infection

of the beet webworm Loxostege sticticalis L (Lepidoptera Crambidae) withthree microsporidia and host switching in Nosema ceranae ParasitologyResearch 1173039ndash3044 httpsdoiorg101007s00436-018-5987-3

Martin WW Warren A (2020) Periplasma gen Nov a new oomycete lineage withisogamous sexual reproduction Mycologia 1ndash14 httpsdoiorg1010800027551420201797385

Martiacuten-Hernaacutendez R Botiacuteas C Barrios L Martiacutenez-Salvador A Meana A Mayack CHiges M (2011) Comparison of the energetic stress associated withexperimental Nosema ceranae and Nosema apis infection of honeybees (Apismellifera) Parasitology Research 109(3)605ndash612 httpsdoiorg101007s00436-011-2292-9

Martiacuten-Hernaacutendez R Higes M Sagastume S Juarranz Aacute Dias-Almeida J BudgeGE Meana A Boonham N (2017) Microsporidia infection impacts the hostcellrsquos cycle and reduces host cell apoptosis PLoS One 12 httpsdoiorg101371journalpone0170183

Mayack C Naug D (2009) Energetic stress in the honeybee Apis mellifera fromNosema ceranae infection Journal of Invertebrate Pathology 100(3)185ndash188httpsdoiorg101016jjip200812001

McCreadie JW Adler PH (1999) Parasites of larval black flies (Diptera Simuliidae)and environmental factors associated with their distributions InvertebrateBiology 118310 httpsdoiorg1023073227000

McInnis T Domnas A (1973) The properties of trehalase from the mosquito-parasitizing water mold Lagenidium sp Journal of Invertebrate Pathology 22313ndash320 httpsdoiorg1010160022-2011(73)90157-2

Mendoza L Vilela R (2013) The mammalian pathogenic oomycetes Current FungalInfection Reports 7198ndash208 httpsdoiorg101007s12281-013-0144-z

Mendoza L Vilela R Humber RA (2018) Taxonomic and phylogenetic analysis ofthe Oomycota mosquito larvae pathogen Crypticola clavulifera FungalBiology 122847ndash855 httpsdoiorg101016jfunbio201804010

Montalva C dos Santos K Collier K Rocha LFN Fernandes EacuteKK Castrillo LA Luz CHumber RA (2016) First report of Leptolegnia chapmanii(Peronosporomycetes Saprolegniales) affecting mosquitoes in Central BrazilJournal of Invertebrate Pathology 136109ndash116 httpsdoiorg101016jjip201603012

Moonjely S Barelli L Bidochka MJ (2016) Insect pathogenic fungi as endophytesAdvanced Genetics 94107ndash135 httpsdoiorg101016bsadgen201512004

Moore SD Duncan LW (2017) Microbial control of insect and mite pests of citrusIn Lacey LA (ed) microbial control of insect and mite pests from theory topractice Academic press pp 283ndash298

Mužinić V Želježić D (2018) Non-target toxicity of novel insecticides Archives ofIndustrial Hygiene and Toxicology 6986ndash102

Neuwirthovaacute N Trojan M Svobodovaacute M Vašiacutečkovaacute J Šimek Z Hofman J Bielskaacute L(2019) Pesticide residues remaining in soils from previous growing season(s)- can they accumulate in non-target organisms and contaminate the foodweb Science of the Total Environment 6461056ndash1062 httpsdoiorg101016jscitotenv201807357

Nikoh N Fukatsu T (2000) Interkingdom host jumping undergroundphylogenetic analysis of entomoparasitic fungi of the genus CordycepsMolecular Biology and Evolution 17(4)629ndash638 httpsdoiorg101093oxfordjournalsmolbeva026341

Olivera IE Fins KC Rodriguez SA Abiff SK Tartar JL Tartar A (2016) Glycosidehydrolases family 20 (GH20) represent putative virulence factors that areshared by animal pathogenic oomycetes but are absent in phytopathogensBMC Microbiology 16(1)1ndash11 httpsdoiorg101186s12866-016-0856-7

Ostroverkhova NV Konusova OL Kucher AN Kireeva TN Rosseykina SA (2020)Prevalence of the microsporidian Nosema spp in honey bee populations(Apis mellifera) in some ecological regions of North Asia Veterinary Sciences7(3)111 httpsdoiorg103390vetsci7030111

Pan G Bao J Ma Z Song Y Han B Ran M Li C Zhou Z (2018) Invertebrate hostresponses to microsporidia infections Developmental amp ComparativeImmunology 83104ndash113 httpsdoiorg101016jdci201802004

Patwardhan A Gandhe R Ghole V Mourya D (2005) Larvicidal activity of thefungus Aphanomyces (oomycetes Saprolegniales) against Culexquinquefasciatus Journal of Communicable Diseases 37269ndash274

Paudel S Sah LP Devkota M Poudyal V Prasad PVV Reyes MR (2020)Conservation agriculture and integrated pest management practices improveyield and income while reducing labor pests diseases and chemicalpesticide use in smallholder vegetable farms in Nepal Sustain 12 httpsdoiorg103390VETSCI7030111

Paul SS Bu D Xu J Hyde KD Yu Z (2018) A phylogenetic census of globaldiversity of gut anaerobic fungi and a new taxonomic framework FungalDiversity 89 httpsdoiorg101007s13225-018-0396-6

Pereira RM (2004) Occurrence of Myrmicinosporidium durum in red imported fire antSolenopsis invicta and other new host ants in eastern United States Journal ofInvertebrate Pathology 86(1-2)38ndash44 httpsdoiorg101016jjip200403005

Porter TM Martin W James TY Longcore JE Gleason FH Adler PH Letcher PMVilgalys R (2011) Molecular phylogeny of the Blastocladiomycota (fungi)based on nuclear ribosomal DNA Fungal Biology 115(4-5)381ndash392 httpsdoiorg101016jfunbio201102004

Powell MJ (2017) Blastocladiomycota In handbook of the Protists Secondedition Pp 1497ndash1521

Powell MJ Lehnen LP Bortnick RN (1985) Microbody-like organelles astaxonomic markers among oomycetes BioSystems 18321ndash334 httpsdoiorg1010160303-2647(85)90032-2

Powell MJ Letcher PM Chambers JG Roychoudhury S (2015) A new genus andfamily for the misclassified chytrid Rhizophlyctis harderi Mycologia 107419ndash431 httpsdoiorg10385214-223

Preston CE Agnello AM Hajek AE (2020a) Nosema maddoxi (microsporidiaNosematidae) in brown marmorated stink bug Halyomorpha halys(Hemiptera Pentatomidae) populations in the United States Biologicalcontrol 144 httpsdoiorg101016jbiocontrol2020104213

Preston CE Agnello AM Vermeylen F Hajek AE (2020b) Impact of Nosemamaddoxi on the survival development and female fecundity of Halyomorphahalys Journal of Invertebrate Pathology 169107303 httpsdoiorg101016jjip2019107303

Quiroz Velasquez PF Abiff SK Fins KC Conway QB Salazar NC Delgado APDawes JK Douma LG Tartar A (2014) Transcriptome analysis of theentomopathogenic oomycete Lagenidium giganteum reveals putativevirulence factors Applied Environmental Microbiology 806427ndash6436 httpsdoiorg101128AEM02060-14

Radek R Herth W (1999) Ultrastructural investigation of the spore-forming protistNephridiophaga blattellae in the Malpighian tubules of the Germancockroach Blattella germanica Parasitology Research 85216ndash231 httpsdoiorg101007s004360050538

Radek R Wellmanns D Wolf A (2011) Two new species of Nephridiophaga(Zygomycota) in the Malpighian tubules of cockroaches ParasitologyResearch 109473ndash482 httpsdoiorg101007s00436-011-2278-7

Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 11 of 13

Radek R Wurzbacher C Gisder S Nilsson RH Owerfeldt A Genersch E Kirk PMVoigt K (2017) Morphologic and molecular data help adopting the insect-pathogenic nephridiophagids (Nephridiophagidae) among the earlydiverging fungal lineages close to the Chytridiomycota MycoKeys 2531ndash50httpsdoiorg103897mycokeys2512446

Roberson RW (2020) Subcellular structure and behaviour in fungal hyphaeJournal of Microscopy 28075ndash85 httpsdoiorg101111jmi12945

Rocha SCO Lopez-Lastra CC Marano AV de Souza JI Rueda-Paacuteramo ME Pires-Zottarelli CLA (2018) New phylogenetic insights into Saprolegniales(Oomycota Straminipila) based upon studies of specimens isolated fromBrazil and Argentina Mycological Progress 17691ndash700 httpsdoiorg101007s11557-018-1381-x

Rossman AY Palm ME (2006) Why are Phytophthora and other Oomycota nottrue fungi Outlooks on Pest Management 17217ndash219

Rueda-Paacuteramo ME Montalva C Arruda W Fernandes KK Luz C Humber RA(2017) First report of Coelomomyces santabrancae sp nov(Blastocladiomycetes Blastocladiales) infecting mosquito larvae (DipteraCulicidae) in Central Brazil Journal of Invertebrate Pathology 149114ndash118httpsdoiorg101016jjip201708010

Sanchez-Pentildea SR Buschinger A Humber RA (1993) Myrmicinosporidium duruman enigmatic fungal parasite of ants Journal of Invertebrate Pathology 6190ndash96 httpsdoiorg101006jipa19931016

Saye LMG Navaratna TA Chong JPJ Orsquomalley MA Theodorou MK Reilly M Li JHeath IB (2021) Chytridiomycetous gut fungi oft overlooked contributors toherbivore digestion Microorganisms 91003ndash1013 httpsdoiorg101139m93-153

Scholte E-J Knols BGJ Samson RA Takken W (2004) Entomopathogenic fungi formosquito control a review Journal of Insect Science 41ndash24 httpsdoiorg1016730310041901

Shen D Nyawira KT Xia A (2020a) New discoveries and applications of mosquitofungal pathogens Current Opinion in Insect Science 40111ndash116 httpsdoiorg101016jcois202005003

Shen D Tang Z Wang C Wang J Dong Y Chen Y Wei Y Cheng B Zhang MGrenville-Briggs LJ Tyler BM Dou D Xia A (2019) Infection mechanisms andputative effector repertoire of the mosquito pathogenic oomycete Pythiumguiyangense uncovered by genomic analysis PLoS Genetics15 httpsdoiorg101371journalpgen1008116

Shen D Wang J Dong Y Zhang M Tang Z Xia Q Nyawira KT Jing M Dou D XiaA (2020b) The glycoside hydrolase 18 family chitinases are associated withdevelopment and virulence in the mosquito pathogen Pythium guiyangenseFungal genetics and Biology135 httpsdoiorg101016jfgb2019103290

Singh G Prakash S (2012) Efficacy of the trichophyton ajelloi and Lagenidiumgiganteum metabolites against mosquitoes after flash chromatographyParasitology Research 1102053ndash2060 httpsdoiorg101007s00436-011-2734-4

Sinha KK Choudhary AK Kumari P (2016) Entomopathogenic fungi In Omkar(ed) ecofriendly Pest Management for Food Security Academic press pp475ndash505

Sokolova YY Weidner E DiMario PJ (2020) Development of Anncaliia algerae(microsporidia) in Drosophila melanogaster Journal of EukaryoticMicrobiology 67125ndash131 httpsdoiorg101111jeu12762

Solter LF Becnel JJ Vaacutevra J (2012) Research methods for entomopathogenicmicrosporidia and other protists In Second E (ed) Lacey LABT-M of T in IPManual of Techniques in Invertebrate Pathology Academic Press San Diegopp 329ndash371

Spatafora JW Sung GH Sung JM Hywel-Jones NL White JF (2007) Phylogeneticevidence for an animal pathogen origin of ergot and the grass endophytesMolecular Ecology 16(8)1701ndash1711 httpsdoiorg101111j1365-294X200703225x

Spies CFJ Grooters AM Leacutevesque CA Rintoul TL Redhead SA Glockling SL ChenCY de Cock AWAM (2016) Molecular phylogeny and taxonomy ofLagenidium-like oomycetes pathogenic to mammals Fungal Biology 120931ndash947 httpsdoiorg101016jfunbio201605005

Spring O Gomez-Zeledon J Hadziabdic D Trigiano RN Thines M Lebeda A(2018) Biological characteristics and assessment of virulence diversity inpathosystems of economically important biotrophic oomycetes CriticalReviews in Plant Sciences 37439ndash495 httpsdoiorg1010800735268920181530848

St Leger RJ Wang C (2010) Genetic engineering of fungal biocontrol agents toachieve greater efficacy against insect pests Applied Microbiology andBiotechnology 85901ndash907 httpsdoiorg101007s00253-009-2306-z

Steele T Bjoslashrnson S (2014) Nosema adaliae sp nov a new microsporidianpathogen from the two-spotted lady beetle Adalia bipunctata L (ColeopteraCoccinellidae) and its relationship to microsporidia that infect othercoccinellids Journal of Invertebrate Pathology 115108ndash115 httpsdoiorg101016jjip201309008

Strassert JFH Wurzbacher C Herveacute V et al Long rDNA amplicon sequencingof insect-infecting nephridiophagids reveals their affiliation to theChytridiomycota and a potential to switch between hosts Scientific Reports396 (2021) httpsdoiorg101038s41598-020-79842-6

Su X (2008) A report of the mosquito host range of Pythium guiyangense SuNature Precedings httpsdoiorg101038npre200818751

Su X Zou F Guo Q Huang J Chen T (2001) A report on a mosquito-killingfungus Pythium carolinianum Fungal Diversity 7129ndash133

Tamim El Jarkass H Reinke AW (2020) The ins and outs of host-microsporidiainteractions during invasion proliferation and exit Cellular Microbiology 22httpsdoiorg101111cmi13247

Tanada Y Kaya HK (2012) Insect pathologyThines M (2018) Oomycetes Current Biology 28R812ndashR813Timofeev S Tokarev Y Dolgikh V (2020) Energy metabolism and its evolution in

microsporidia and allied taxa Parasitology Research 119(5)1433ndash1441httpsdoiorg101007s00436-020-06657-9

Tokarev YS Huang WF Solter LF Malysh JM Becnel JJ Vossbrinck CR (2020) Aformal redefinition of the genera Nosema and Vairimorpha (microsporidiaNosematidae) and reassignment of species based on molecularphylogenetics Journal of invertebrate pathology 169 169107279 httpsdoiorg101016jjip2019107279

Tokarev YS Zinatullina ZY Ignatieva AN Zhigileva ON Malysh JM Sokolova YY(2018) Detection of two microsporidia pathogens of the European honeybee Apis mellifera (Insecta Apidae) in Western Siberia Acta Parasitologica 63728ndash732 httpsdoiorg101515ap-2018-0086

Trigos-Peral G Rutkowski T Wojtaszyn G Espadaler X (2017) Myrmicinosporidiumdurum in Poland a new location for this fungal ant endoparasite and updatedworld distribution Acta Parasitologica httpsdoiorg101515ap-2017-0106

Valizadeh P Guzman-Novoa E Goodwin PH (2020) Effect of immune inducers onNosema ceranae multiplication and their impact on honey bee (Apis melliferaL) survivorship and behaviors Insects 11572 httpsdoiorg103390insects11090572

van West P Beakes GW (2014) Animal pathogenic oomycetes Fungal Biology118525ndash526 httpsdoiorg101016jfunbio201405004

Verheggen FJ Vogel H Vilcinskas A (2017) Behavioral and immunologicalfeatures promoting the invasive performance of the harlequin ladybirdHarmonia axyridis Frontiers in Ecology and Evolution 5

Vilcinskas A Schmidtberg H Estoup A Tayeh A Facon B Vogel H (2015) Evolutionaryecology of microsporidia associated with the invasive ladybird Harmonia axyridisInsect Sci 22313ndash324 httpsdoiorg1011111744-791712159

Vilela R Humber RA Taylor JW Mendoza L (2019) Phylogenetic and physiologicaltraits of oomycetes originally identified as Lagenidium giganteum from flyand mosquito larvae Mycologia 111(3)408ndash422 httpsdoiorg1010800027551420191589316

Vilela R Montalva C Luz C Humber RA Mendoza L (2018) Pythium insidiosumisolated from infected mosquito larvae in Central Brazil Acta Tropica 185344ndash348 httpsdoiorg101016jactatropica201806014

Vilela R Taylor JW Walker ED Mendoza L (2015) Lagenidium giganteumpathogenicity in mammals Emerging Infectious Diseases journal 21(2)290ndash297 httpsdoiorg103201eid2102141091

Vyas N Dua KK Prakash S (2007) Efficacy of Lagenidium giganteum metaboliteson mosquito larvae with reference to nontarget organisms ParasitologyResearchParasitology Research 101385ndash390 httpsdoiorg101007s00436-007-0496-9

Walker CA van West P (2007) Zoospore development in the oomycetes FungalBiologyogy Reviews 21(1)10ndash18 httpsdoiorg101016jfbr200702001

Wallace Martin W (2000) Two new species of Couchia parasitic in midgeeggs Mycologia 921149ndash1154 httpsdoiorg10108000275514200012061262

Wang C Wang S (2017) Insect pathogenic fungi genomics molecularinteractions and genetic improvements Annual Review of Entomology 6273ndash90 httpsdoiorg101146annurev-ento-031616-035509

Wang Y Ma Y Wang D Liu W Chen J Jiang Y Yang R Qin L (2019) Polartube structure and three polar tube proteins identified from Nosemapernyi Journal of Invertebrate Pathology168 httpsdoiorg101016jjip2019107272

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Weiss LM (2020) Microsporidiosis In Ryan ET hill DR Solomon T Aronson NEEndy TP (eds) Hunterrsquos tropical medicine and emerging infectious diseases(tenth edition) tenth edit Content repository only London pp 825ndash831

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Wylezich C Radek RSM (2004) Phylogenetische analyse der 18S rRNA identifiziertden parasitischen Protisten Nephridiophaga blattellae (Nephridiophagidae)als Vertreter der Zygomycota (fungi) Denisia 13435ndash442

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Kaczmarek and Boguś IMA Fungus (2021) 1229 Page 13 of 13