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Revista Brasileira de Entomologia 62 (2018) 275–282

REVISTA BRASILEIRA DE

EntomologiaA Journal on Insect Diversity and Evolution

www.rbentomologia .com

iology, Ecology and Diversity

opulation analysis of white grubs (Coleoptera: Melolonthidae)hroughout the Brazilian Pampa biome

vair Valmorbidaa,∗, Mariana Alejandra Chermanb, Clérison Régis Perinia, Lucas de Arruda Cavallina,erson Vanderlei Carús Guedesa

Universidade Federal de Santa Maria, Departamento de Protec ão de Plantas, Santa Maria, RS, BrazilUniversidade Federal do Paraná, Departamento de Zoologia, Curitiba, PR, Brazil

r t i c l e i n f o

rticle history:eceived 26 January 2018ccepted 17 August 2018vailable online 31 August 2018ssociate Editor: Adeney de Freitas Bueno

eywords:opulation densityiloboderus abderuslectrisrasslandsultivated areas

a b s t r a c t

The replacement of natural grassland by cultivated areas might favor the increase in abundance of someroot-feeding species such as the white grubs, which may become a constraint for field crop production.This research aimed to assay the population density and geographical distribution of white grubs pestand other species in natural grassland and cultivated areas throughout the Brazilian Pampa biome. Whitegrubs were sampled in 18 locations in both landscape use types and identified. Population density (num-ber of larvae m−2) was calculated for each recorded species and sorted within two groups (pest speciesand other species), compared between natural grasslands and cultivated areas, as well as among locations.A dendrogram to evaluate species similarity among locations was built based on combined data obtainedfrom both landscape use types throughout the region. In total, 31 species were found in the BrazilianPampa, and four of them are considered as crop pests: Diloboderus abderus (Sturm, 1826), Euetheolahumilis (Burmeister, 1847), Lyogenys fusca (Blanchard, 1830), and Phyllophaga triticophaga Morón & Sal-vadori, 1998. The average population density of pest species in cultivated areas was less than five larvaem−2, at most of locations. Some species had a wide geographical distribution (e.g. D. abderus and Cyclo-

cephala modesta Burmeister), while other melolontids occurred at only one location. The knowledge ofwhich white grub species are present in a field and its population densities assist farmers to take propermanagement decisions.

© 2018 Published by Elsevier Editora Ltda. on behalf of Sociedade Brasileira de Entomologia. This is anopen access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/

ntroduction

The Brazilian Pampa biome is located in the of Rio Grande doul State, where it occupies an area of 176.5 mil km2 (IBGE, 2004).ts vegetation is composed primarily of grass species (Paspalumpp. Axonopus jesuiticus, Aristida spp., and Bouteloua megapotam-ca) (Boldrini et al., 2010). The climate of this region is classifieds “Cfa” and “Cfb” according to the Köppen climatic classificationAlvares et al., 2017).

The natural grasslands areas of the Brazilian Pampa have beeneplaced by croplands (Boldrini, 2009; Silveira et al., 2017), with aarge increase in the area sowed with summer crops (over a million

ectares) in the period from 2000–2015 due to a rise in commod-

ty prices (Silveira et al., 2017). The increase in crop acreage haseen from soybean, wheat, and rice (Gressler, 2008; Silva, 2012).

∗ Corresponding author.E-mail: ivairvalmorbida@gmail.com (I. Valmorbida).

https://doi.org/10.1016/j.rbe.2018.08.002085-5626/© 2018 Published by Elsevier Editora Ltda. on behalf of Sociedade Brasileira dereativecommons.org/licenses/by-nc-nd/4.0/).

).

The areas with increase soybean and corn acreage during the warmseason, and oats (Avena spp.), wheat (Triticum aestivum), and rye-grass (Lolium spp.) in the cool season have been the uplands, whilethe areas with increase rice acreage are in the lowlands (Gressler,2008).

The conversion of natural grassland into cultivated areas and theadoption of some agricultural practices might favor some root feed-ing insects such as the white grubs (Morón, 1996). White grubs arelarvae of the beetles belonging to the family Melolonthidae. Somespecies are rhizophagous and considered serious pests of many cul-tivated plants, despite its ability to improve soil quality (Oliveiraand Salvadori, 2012). Thus, an increase of population densitiesof pest species might become a predicament for crop production(Salvadori and Pereira, 2006).

In Brazil, less than one percent of all Melolonthidae species

recorded have been reported damaging crops and about five per-cent are associated to croplands (Morón, 2004). In most cases,control measures have been taken without knowing the accuratepopulation density and species of white grubs present in a field,

Entomologia. This is an open access article under the CC BY-NC-ND license (http://

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76 I. Valmorbida et al. / Revista Brasil

eading to incorrect management strategies. The use of inappro-riate management strategies may affect the abundance of whiterubs and reduce beneficial species, while triggering the increase ofopulation density and dispersion of pest species (Solís and Morón,998).

In the 1980s, some species of Melolonthidae became pest onrops in the state of Rio Grande do Sul (southern Brazil) (Salvadorind Oliveira, 2001; Silva and Costa, 2002). The pasture white grub,iloboderus abderus (Sturm) and the wheat white grub, Phyllophaga

riticophaga Morón & Salvadori are the most important white grubests of wheat, corn, and soybean in the Planalto region of Riorande do Sul state (Salvadori and Pereira, 2006). Cyclocephalaavipennis Arrow has also been found abundantly in cultivatedreas (Salvadori and Pereira, 2006; Cherman et al., 2014a). Thispecies has been considered as harmless even at high popula-ion density at farming conditions in southern Brazil, despite ofeeding on wheat roots in greenhouse bioassays (potted wheatlants) (Salvadori and Pereira, 2006). However, C. flavipennis waseported damaging blueberry roots in southern Rio Grande doul (Diez-Rodríguez et al., 2015) and perennial winter pasturesn Santa Catarina State (Duchini et al., 2017). In addition, Plec-ris (= Demodema) brevitarsis (Blanchard) has been found feedingn soybean roots (Morón and Salvadori, 2006) and Liogenys fuscalanchard associated to winter crops (Cherman et al., 2011). Dis-ribution and population density of non-pest species are well

ocumented for the north region of Rio Grande do Sul (e.g. Chermant al., 2013, 2014b).

For the south region of Rio Grande do Sul, the area that compriseshe Brazilian Pampa, Euetheola humilis (Burmeister) was reported

able 1ocations, previous and current crop, collection date, sampled area, and number of trench

Location Latitude (S) Longitude (W) Previous crop

Cultivated areasAlegrete 29◦45′S 55◦40′W Corn

Cac apava do Sul 30◦28′S 53◦28′W Corn

Cacequi 29◦54′S 54◦47′W Soybean

Dom Pedrito 31◦03′S 54◦29′W Corn

Itacurubi 28◦55′S 55◦11′W Soybean

Itaqui 29◦13′S 56◦28′W Rice

Rosário do Sul 30◦17′S 54◦58′w Corn

São Borja 28◦38′S 55◦59′W Soybean

Uruguaiana 29◦48′S 57◦54′W Millet

Vila Nova do Sul 30◦21′S 53◦57′W Corn

Cachoeira do Sul 29◦51′S 52◦41′W Soybean

Restinga Seca 29◦49′S 53◦ 17′W Soybean

São Gabriel 30◦22′S 54◦23′W Corn

São Sepé 30◦00′S 53◦41′W Soybean

Bagé 31◦19′S 53◦58′W Soybean

Pinheiro Machado 31◦35′S 53◦15′W Corn

Arroio Grande 32◦13′S 53◦14′W Soybean

Herval 32◦03′S 53◦23′W Corn

Natural grassland areasAlegrete 29◦44′S 55◦40′W Natural grasslanCac apava do Sul 30◦27′S 53◦28′W Natural grasslanCacequi 29◦54′S 54◦47′W Natural grasslanDom Pedrito 31◦04′S 54◦29′W Natural grasslanItacurubi 28◦54′S 55◦11′W Natural grasslanItaqui 29◦11′S 56◦30′W Natural grasslanRosário do Sul 30◦17′S 54◦59′w Natural grasslanSão Borja 28◦38′S 55◦59′W Natural grasslanUruguaiana 29◦48′S 57◦5,4′W Natural grasslanVila Nova do Sul 30◦20′S 53◦57′W Natural grasslanCachoeira do Sul 29◦52′S 52◦42′W Natural grasslanRestinga Seca 29◦49′S 53◦ 16′W Natural grasslanSão Gabriel 30◦22′S 54◦24′W Natural grasslanSão Sepé 30◦00′S 53◦40′W Natural grasslanBagé 31◦18′S 53◦58′W Natural grasslanPinheiro Machado 31◦36′S 53◦16′W Natural grasslanArroio Grande 32◦13′S 53◦15′W Natural grasslanHerval 32◦03′S 53◦23′W Natural grasslan

Entomologia 62 (2018) 275–282

damaging rice (Ferreira and Barrigossi, 2006). In the same region,E. humilis and D. abderus were reported damaging Eucalyptus spp.(Bernardi et al., 2008; Garlet et al., 2009). Despite these records,knowledge on population density and distribution of melolontids“as a whole”, is lacking for the Brazilian Pampa. This is necessary todevelop and implement successful and site-specific managementstrategies.

Here, we report the population density and distribution of whitegrub pest and other species in the Brazilian Pampa biome. Whitegrubs were collected in cultivated and natural grassland areas in18 locations to test the following hypotheses: (1) cultivated areasincrease the population density of pest species; (2) population den-sity of other species is greater in natural grassland areas than incultivated areas; (3) the white grub species composition variesaccording to the phytophysionomic units of the Brazilian Pampa.

Materials and methods

Study area and locations

Within the Brazilian Pampa 18 locations (Table 1; Onlineresource 1) were chosen to sample white grubs, localized atdifferent phytophysionomic units (Hasenack et al., 2010). Rep-resentatives areas in terms of crop production or that have beenconverted from natural grassland to cultivated areas were sam-pled. Moreover, the locations and areas were selected based on

information gathered by extension field agronomists and farmers,regarding the occurrence of white grubs, land accessibility, andthe presence of a natural grassland area nearby a cultivated

es (n) for cultivated and natural grassland areas in the Brazilian Pampa.

Current crop Data Area (hectares) n

Oat + Italian ryegrass 10/25/2012 9.5 25Oat + Italian ryegrass 10/19/2012 3 25Oat 10/26/2012 9.2 25Oat + Italian ryegrass 11/15/2012 5 25Oat + Italian ryegrass 10/10/2012 5 25Italian ryegrass 10/9/2012 6 25Oat + Italian ryegrass 10/26/2012 6.2 25Wheat 10/9/2012 9 25Italian ryegrass 10/25/2012 12.5 25Italian ryegrass 10/19/2012 6.5 25Oat + Italian ryegrass 5/25/2013 5.67 34Italian ryegrass 5/31/2013 3.79 31Italian ryegrass 8/20/2013 4.5 25Oat 8/20/2013 5 25Italian ryegrass 8/27/2013 4 25Italian ryegrass 8/27/2013 1.5 25Italian ryegrass 8/28/2013 10 25Italian ryegrass 8/28/2013 6 25

d 10/25/2012 7.5 25d 10/19/2012 9.5 25d 10/26/2012 1.5 25d 11/15/2012 6 25d 10/10/2012 6 25d 10/9/2012 6 25d 10/26/2012 5.3 25d 10/9/2012 1 25d 10/25/2012 6 25d 10/19/2012 5 25d 5/25/2013 5.56 34d 5/31/2013 5.1 32d 8/20/2013 10.5 25d 8/20/2013 7 25d 8/27/2013 8 25d 8/27/2013 3.5 25d 8/28/2013 3 25d 8/28/2013 8 25

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ne. Natural grassland areas were considered those with naturalegetation (grasslands) used to raise cattle, and cultivated areasere those that have been used as cropland for at least ten years.

ample procedure

Samples were taken during 2012 and 2013 in 18 locationshroughout the Brazilian Pampa biome. We performed soil samplesrom May to November because species with known bioecology aret larval stage during this period in Rio Grande do Sul State (e.g. D.bderus and P. triticophaga; Pereira and Salvadori, 2006; Salvadorind Pereira, 2006). At least 25 trenches (50 × 25 × 30 cm deep) wereandomly opened in both cultivated and natural grassland areas atach location. The soil of each trench was carefully handled to verifyhe presence of larvae and adults of Melolonthidae. The specimensere individually placed into 70 mL plastic pots containing trench’s

oil and transported to the Laboratório de Manejo Integrado deragas of the Universidade Federal de Santa Maria.

pecimen identification

Melolonthidae larvae were identified using a stereoscopicicroscope (5x magnification), taxonomic keys and morphologi-

al descriptions of Frana (2003), Pereira and Salvadori (2006), andherman et al. (2013). For those specimens at larval stage thatas not possible to identify, we reared them to adult stage. For

his, the larvae were kept individually into 70 mL pots contain-

ng trench’s soil and a carrot dice in growth chambers (25 ± 1 ◦Cnd 12:12 h light:dark cycle) (Aragón et al., 2005). The pots wereerified weekly for adult emergence, soil moisture, and to replacehe carrot dices. Vouchers of larvae and adults were deposited at

ig. 1. Population density of white grubs (mean ± SE) in natural grassland and cultivatedignificantly by bootstrap t-test (p ≤ 0.05).

Entomologia 62 (2018) 275–282 277

the following collections: Colec ão Entomológica do Departamentode Defesa Fitossanitária (Universidade Federal de Santa Maria, RioGrande do Sul); DZUP (Colec ão Entomológica Pe. Jesus SantiagoMoure, Departamento de Zoologia, Universidade Federal do Paraná,Curitiba), and CERPE (Colec ão Entomológica da Universidade Fed-eral de Pernambuco, Recife).

Statistical analysis

The absolute abundance data (number of specimens of eachspecies) of each sampled area was used to calculate the rela-tive abundance for each species (larvae m−2). Then, the specieswere sorted within two groups based on available literature: pestand other species. The “other species” category is not consid-ered as simply “non-pests” because it may have both beneficialand/or potential pest species (facultative rhizophagous habits, e.g.C. flavipennis). In the category of “pests” are only those that havealready been recorded in the literature causing injuries to culti-vated plants. The total average of white grubs density (larvae m−2)was compared between cultivated and natural grassland areasand within groups (pest species vs other species), using boot-strap t-test analysis (10,000 repetitions) at 95% confidence interval,performed in the software BIOSTAT 5.Ø (Ayres et al., 2007). Datafrom cultivated and natural grassland areas of each location andall sampled sites was combined into a unique data set to com-

pare similarities of species composition among locations. Clusteranalysis based on Jaccard’s similarity relationship (as it counts pres-ence/absence) was plotted using the software PAST 3.0 (Hammeret al., 2001).

areas in the Brazilian Pampa. Pairs of columns with the same letters do not differ

278 I. Valmorbida et al. / Revista Brasileira de Entomologia 62 (2018) 275–282

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opulation density of white grubs in cultivated and naturalrassland areas

In total, 1365 specimens belonging to 31 species were collectedn cultivated and natural grasslands areas of the Brazilian Pampa.opulation density of white grubs in natural grassland areas wasignificantly greater than in cultivated areas in nine out of 18 sam-led sites (Fig. 1). On average, larval density of all natural grasslandreas was significantly greater than in cultivated areas (p < 0.05,7.25 and 5.8 larvae m−2, respectively), ranging from 57.25 to.28 (natural grassland) and 17.6 to 0.32 larvae m−2 (cultivatedreas). The greatest number of white grubs in natural grasslandsere observed in Restinga Seca (57.25 larvae m−2), Dom Pedrito

45.44 larvae m−2), and Cacequi (34.24 larvae m−2). The speciesomposition was mainly by Plectris griseovestita Moser, Plectris sp.5,nd L. fusca, respectively. São Borja and Arroio Grande were thenly two localities where the mean white grub density was greatern cultivated than in natural grassland areas; however, it did notiffer significantly (p > 0.05). Uruguaiana (17.6 larvae m−2), Itaqui16.9 larvae m−2), and Pinheiro Machado (11.2 larvae m−2) had thereatest density of white grubs in cultivated areas.

opulation density of white grubs pest and other species

D. abderus, E. humilis, L. fusca, and P. triticophaga are among thepecies collected that have been reported damaging plants. In nat-ral grasslands areas, the mean density of white grubs pest was

assland areas in the Brazilian Pampa. Pairs of columns with the same letters do not

4.48 larvae m−2 (28.48 to zero), while in cultivated areas it was1.46 larvae m−2 (8.64 to zero) (Figs. 2 and 3). Cacequi and RestingaSeca were the two locations with population of pest species over10 larvae m−2 in natural grassland areas. The mean populationdensity for other species (non-pest species) was 12.82 in naturalgrassland areas (45.44 to 0.32) and 4.36 larvae m−2 in cultivatedareas (17.6 to zero). The population density of white grubs pest wassignificantly greater in Cacequi (natural grasslands) and in Alegreteunder cultivated areas (Figs. 2 and 3). Great densities of D. abderusand L. fusca were observer in Cacequi (natural grassland area) andD. abderus in Restinga Seca (natural grassland area) and Alegrete(cultivated area) (Online resources 2 and 3).

Occurrence and distribution of white grub pest and other species

D. abderus was found in 15 out of 18 locations sampled (fiveonly in cultivated areas, three in natural grassland areas, and sevenlocations in both land use types). This species was followed by E.humilis that was found in four locations in natural grasslands andone in both land use types. L. fusca was found in one natural grass-lands, one cultivated area, and two locations in both landscapes. Forthose considered as other species, Cyclocephala modesta Burmeis-ter was found in 13, followed by Dicrania sp. (six locations), andLeucothyreus sp.1 and P. griseovestita (five locations). Eight speciesoccurred in two locations and a group of eleven species was found

only in one locality each (Fig. 4).

The clustering analysis using Jaccard index (Fig. 5) demonstrateda pattern of species distribution throughout Brazilian Pampa. Thepattern of species distribution formed groups comprising habitats

I. Valmorbida et al. / Revista Brasileira de Entomologia 62 (2018) 275–282 279

F tivateds

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ig. 3. Population density of white grubs pest and other species (mean ± SE) in culignificantly by bootstrap t-test (p ≤ 0.05).

ccording to the phytophysionomic units of the Brazilian Pampa.he phytophysionomic “Vegetac ão Parque” included the locationsf Uruguaiana and Itaqui. The “Campos do Centro do Estado”ncluded Rosário do Sul and Cacequi, and “Campos Barbas-de-bode”omprised the locations of Itacurubi, São Borja, and Alegrete. Inddition, Vila Nova do Sul, Cac apava do Sul, São Sepé, and Res-iga Seca were included in another group. Two groups were formedomprising habitats between the phytophysionomic units of “Cam-os Savanóides” and “Campos Solos Profundos” (Arroio Grande,inheiro Machado, Bagé, and Herval). Moreover, the location ofão Gabriel that belongs to a transition zone and Dom Pedrito thatelongs to “Campos Solos Profundos” did not cluster with any otherroup.

iscussion

The overall mean density of pest species in cultivated areas wasower than the known economic threshold established for pestontrol. For D. abderus and P. triticophaga in winter cereals, theconomic threshold is five white grubs m−2 (Salvadori and Pereira,006). Density of pest species above this in cultivated areas wasbserved only in Alegrete, where D. abderus was predominant. Theccurrence of high densities of white grubs in a cultivated area doesot mean all larvae are of pest species, and when misidentified, itight lead to management mistakes (Cherman et al., 2014b). For

his, site-specific monitoring of white grubs should be taken eachrowing season as a basis of an Integrated Pest Management (IPM).

oreover, the economic thresholds may change due to economic

onditions (e.g. treatment cost, production value) and pest densityPedigo et al., 1986), and it is prudent to consider before taking any

anagement decisions.

areas of the Brazilian Pampa. Pairs of columns with the same letters do not differ

We assessed population density and distribution of white grubpest and other species in the Brazilian Pampa. Four out of 31 speciesfound in this study are considered as pest species; three of them (D.abderus, E. humilis, and P. triticophaga) had already been reporteddamaging crops in southern Brazil (Ferreira and Barrigossi, 2006;Salvadori and Pereira, 2006). L. fusca was included as a pest speciesdue to its crop damage in the Central-West Region of Brazil (Santoset al., 2008a; Costa et al., 2009). D. abderus, L. fusca, and P. triti-cophaga also were reported in cultivated areas of the Planalto regionof Rio Grande do Sul (Cherman et al., 2014b), and can be consideredthe most common pest species of cultivated areas in the state of RioGrande do Sul.

Among the pest species, D. abderus was widely distributedthroughout the Brazilian Pampa (15 out of 18 sampled locations)suggesting this species is well adapted to the environmental andland management uses in southern Brazil. Indeed, D. abderus isknown to be present in cultivated and natural areas through-out Rio Grande do Sul State (Silva and Salvadori, 2004; Chermanet al., 2014a). Its presence and dispersion into cultivated areashas increased after implementation of no-tillage system becausefemales fly to find places with crop residues to build nests and laytheir eggs (Silva et al., 1994).

This study also reports the occurrence of P. triticophaga in theBrazilian Pampa. P. triticophaga was found only in Dom Pedrito (cul-tivated area) and Pinheiro Machado (natural grassland area). Thisspecies has a two-year life cycle and is found in both tillage andno-tillage fields (Salvadori and Pereira, 2006), and has a wide dis-tribution in the north of Rio Grande do Sul (Salvadori and Pereira,

2006; Cherman et al., 2013). P. triticophaga and D. abderus are con-sidered the most important white grubs pest of rainfed crop fieldsin South Brazil due to their damage potential to winter cereals, corn,and soybean (Salvadori and Pereira, 2006).

280 I. Valmorbida et al. / Revista Brasileira de Entomologia 62 (2018) 275–282

Diloboderus abderus

Cyclocephala modesta

Dicrania sp.

Euetheola humilis

Plectris griseovestita

Geniates sp.

Leucothyreus sp.1

Liogenys fusca

Plectris affinis decipiens

Liogenys sinuaticeps

Cyclocephala flavipennis

Chalepides anomalus

Eunanus sp.

Plectris sp.1

Plectris sp.2

Phyllophaga triticophaga

Leucothyreus sp.3

Leucothyreus sp.4

Plectris sp.3

Alvarinus sp.

Blepharotoma uniformis

Cyclocephala tucumana

Heterogomphus sp.

Liogenys bidenticeps

Liogenys concolor

Leucothyreus sp.2

Leucothyreus sp.5

Rhizogeniates sp.2

Plectris sp.4

Plectris sp.5

Rhizogeniates sp.1

4

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Fig. 4. Melolonthidae species and num

In the group of species that are not considered pests, C. modestaas reported in 13 out of 18 locations sampled (nine in cultivated

reas). This species is widely distributed and very abundant in bothultivated and non-cultivated areas throughout north of Rio Grandeul (Cherman et al., 2014a). The occurrence of C. modesta in culti-ated areas might be linked to the insertion of plants of the familyabaceae (e.g. soybean) in crop rotation systems (Zerbino, 2002).o date, no injury on field crops was reported in Brazil; however,. modesta was reported damaging improved natural pasture fields

n Uruguay (Morelli and Alzugaray, 1990) and is associated to thehite grubs complex of wheat in Argentina (Massaro, 2010). Theonitoring of C. modesta and other species that have not yet been

eported as field crop pest, but belong to genus that contain pestpecies in Brazil (e.g. Plectris and Liogenys) is important to earlierdentification of problems and to properly apply strategies of pest

anagement.

Due to difficulties to sample and identify Melolonthidae at lar-

al stage, farmers have adopted preventive control approaches toeduce population densities of white grubs in cultivated areas. Cur-ent management strategies to control white grubs in Brazil rely

6 8 10 12 14 16

locations that each species was found.

on the use of synthetic insecticides delivered by seed treatment(Santos et al., 2008b), yet without knowing the accurate popula-tion density and white grubs species. The use of insecticides everygrowing season over large areas increase the chance of resistancedevelopment and disrupting of natural enemies (predators and par-asitoids), which may increase the dependency on chemical control(Koppenhöfer and Fuzy, 2008).

The cluster analysis allowed us to detect patterns of speciesdistribution linked to the phytophysionomic units of the Brazil-ian Pampa based on vegetation and soil composition proposed byHasenack et al. (2010). For example, Eunanus sp. only occurred inthe physiognomy “Vegetac ão Parque” that comprises the locationsof Itaqui and Uruguaiana, and Chalepides anomalus Martínez waspresent only in the “Campos do Centro do Estado” (Cacequi andRosário do Sul). The assemblage of white grubs species differs instructure and abundance from one region to another, depending on

the landscape, vegetation, and climate of different localities (Pardo-Locarno et al., 2003). Although these findings demonstrate thatspecies occurrence might be associated to the phytophysionomicunits of the Brazilian Pampa, sampling white grubs throughout the

I. Valmorbida et al. / Revista Brasileira de Entomologia 62 (2018) 275–282 281

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ig. 5. Dendrogram representing results of a cluster analysis of Melolonthidae spampa.

ear and using other sampling methods (e.g. light trap) is importanto confirm the patterns observed.

Our results demonstrated that at most of cultivated areas, theopulation density of pest species did not exceed economic thresh-ld for winter cereals. Furthermore, the relationship between theccurrence of white grubs in one year and its presence in theame or next year is tenuous because larval occurrence might benfluenced by many biotic and abiotic factors. Due to many partic-larities regarding the white grubs biology, we highly encouragearmers and extension agronomists to scout fields before plantingo take proper management decisions, follow economic thresholdsor each pest species, and combine control tactics to have betterutcomes. In conclusion, control decisions for white grub pestsust follow the basis for IPM and threshold levels for each pest

pecies, taking into consideration the relation between white grubensity, crop, damage, and control costs.

onflicts of interest

The authors declare no conflicts of interest.

cknowledgements

We thank Dr. Paschoal Coelho Grossi and Dr. Miguel Angelorón (in memorian) for aiding in the identification of some bee-

les. We also thank Dane Block Araldi, Mirian Barbieri, Moisésoschetti, Bruno Tomazzi, Lucas Bilhão, Diego Coppetti, Régis Felipetacke, and Maicon Machado for helping in specimens sampling.o Coordenac ão de Aperfeic oamento de Pessoal de Nível SuperiorCAPES) for granting a scholarship to the first author.

ppendix A. Supplementary data

Supplementary data associated with this article can be found, inhe online version, at doi:10.1016/j.rbe.2018.08.002.

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