The carrot psyllid, Trioza apicalis biology and control psyllid BIOFORSK RAPPORT… · The carrot psyllid, Trioza apicalis - biology and control ... Carrot psyllid, Trioza apicalis

Forfatter, Bioforsk rapport nr. Side 1

Bioforsk Rapport

Bioforsk Report Vol. 5 Nr. 151 2010

The carrot psyllid, Trioza apicalis - biology and control

Gulrotsuger, Trioza apiclis - biologi og bekjempelse

Richard Meadow

Bioforsk Plantehelse

Hovedkontor/Head office Frederik A. Dahls vei 20 N-1432 Ås Tel.: (+47) 40 60 41 00 [email protected]

Bioforsk Senter Bioforsk Division Adresse Postnummer og poststed Tel.: (+47) 40 60 41 00 [email protected]

Tittel/Title:

Carrot psyllid, Trioza apicalis - biology and control

Forfatter(e)/Author(s):

Richard Meadow

Dato/Date: Tilgjengelighet/Availability: Prosjekt nr./Project No.: Saksnr./Archive No.:

01.11.2010 Åpen 1110406 Arkivnr

Rapport nr./Report No.: ISBN -13-nr./ISBN-no: Antall sider/Number of pages:

Antall vedlegg/Number of appendices:

5(151)/2010 978-82-17-00707-4 Sider Vedlegg

Oppdragsgiver/Employer: GA-FA Vestfold www.gafa.no

Kontaktperson/Contact person: Lars-Arne Høgetveit [email protected]

Stikkord/Keywords: Fagområde/Field of work:

Gulrotsuger, gulrot, bekjempelses strategier, feller, alternative metoder

Plantevern

carrot psyllid, carrot, IPM, traps, alternative control

Plant protection

Sammendrag:

Denne rapporten er en del av et forstudie som har som mål å finne frem til midler og metoder for bekjempelse av gulrotsuger. Gulrotsuger er en alvorlig skadegjører der den slår til. Men utbredelsen som viktig skadedyr er begrenset til Norge, Sverige og Finland. Den er også kjent som skadedyr i noen få land lengre sør, som Sveits. Av den grunn har det vært få vitenskapelige undersøkelser og det er lite som er kjent om artens biologi og adferd. Dette gjør det vanskelig å lage til bekjempelses strategier som kan lykkes. Av de få studier som er gjort har noen gått grundig til verks, bl.a. Rygg i 1977. Rapporten gir en oversikt over det som er kjent om gulrotsugeren som kan bygges på med videre forskning til å komme nærmere en vellykket bekjempelse.

Summary:

This report is part of a preliminary study with the goal of finding control measures and methods to manage the carrot psyllid. The psyllid is serious pest in the areas it attacks. But its distribution as an economic pest is limited to Norway, Sweden and Finland. It is also recognized as an occasional pest in some parts of Central Europe, such as Switzerland. For this reason, there have been very few scientific studies on this species and little is known about its biology and behavior. This causes difficulty in designing successful management strategies. Of the few studies that have been done, some have been very thorough as was the study by Rygg in 1977. The report gives an overview of most of what is known about the carrot psyllid that can be used as a basis for further research toward the goal of successful management of this pest.

Land/Country: Fylke/County:

Norge Akershus

Kommune/Municipality: Ås

Sted/Lokalitet: Ås

Meadow. Bioforsk Rapport vol. 5 nr. 151 2010

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This report was commissioned by the Norwegian Agricultural Extension Service office GA-FA Vestfold and is financed by GA-FA, Fylkesmannen i Vestfold and Gartnerhallen AL. The background for the commission was the extreme difficulty in controlling the insect pest Trioza apicalis, the carrot psyllid or carrot sucker. As a result of ineffective control, the carrot psyllid causes damage and losses amounting to millions of kroner each year in the regions of attack. Distribution, Biology and Life-cycle In Norway, the regions with reported attack of the carrot psyllid are southeastern and eastern Norway from Aust-Agder to Hedmark as well as some areas in Nord-Trøndelag. This distribution does not appear very different from the assumed distribution reported by Rygg in 1977. In addition to Norway, the carrot psyllid has long been the cause of damage of economic importance annually in parts of Sweden and Finland (Nissinen et al. 2007; Nehlin et al. 1994). It is also known as an occaisional pest in central Europe, including Switzerland (Láska 1974; Burckhardt & Freuler 2000). Because of its relatively limited importance outside the Nordic countries, the carrot psyllid has been the subject of very little study in the scientific community. This report collects the current knowledge of the carrot psyllid in relation to controlling the pest and limiting the damage it causes to the crop, with the aim of providing a basis for further studies to help alleviate this pest problem. The carrot psyllid has one generation per year. It tolerates cold climates and is unharmed by winter temperatures of -18°C (Rygg 1977) and possibly as cold as -30°C (A. Nissinen pers. com.). It overwinters in the adult stage in coniferous trees, preferably Norway spruce (Láska 1974, Rygg 1977). This preference was confirmed in a recent study in Sweden where only a few individuals were found on pine, yew, thuja or other conifers, while the greatest proportion (over 80%) were in Norway spruce (Kristoffersen & Anderbrant 2007). In the same study, carrot psyllids were found as far as 1 km from carrot fields. The maximum distance that the carrot psyllid can fly is not known. The adult carrot psyllids (fig. 1) leave their winter host in late spring, usually at the time when the main carrot crop is emerging. Observations in recent years in southern Lågendalen in Norway, an area with high populations, indicate that immigration began the last week in May (L.-A. Høgetveit pers. com.). It is currently unknown which cues initiate the carrot psyllid's migration from its winter host to its summer host. It is likely that it is a combination of daylength and the quality of the winter host as a nutritional source, as is the case for migratory aphids. Immigration into carrots often occurs at roughly the same time as emergence of the carrots from the soil. Rygg (1977) found that there was a higher rate of flight on days with higher temperature and more hours of sunshine. Both males and females are found in carrot fields and the assumption is that carrot psyllids mate on carrots (Kristoffersen & Anderbrant 2007).


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Fig. 1. Adult carrot psyllid. Photo: Bioforsk The carrot psyllid also has a strong preference concerning its summer host. Studies have shown that it chose carrot over other host plants (Rygg 1977; Nehlin et al. 1996). Rygg also found that the carrot psyllid could not complete its development on other hosts he investigated. In other studies, where the females were not given a choice of host plants, they layed eggs on several species related to carrot and the larvae were able to develop on most of these (Valterová et al. 1997). When the adults have settled on the carrot plants they begin feeding. They feed by inserting a stylet into the plant tissue (Hodkinson 1974) and suck nutrients from the phloem. Feeding by carrot psyllid causes curling of the youngest leaves (fig. 2), not necessarily directly at the feeding site. This is assumed to be the result of a toxin that is transported systemically in the plant causing other symptoms, including wilting and death of the plants (Markkula & Laurema 1971). The toxin is unknown, but recent studies have shown an association between the carrot psyllid and the plant pathogenic bacterium Candidatus Liberibacter solanacearum (Munyaneza et al. 2010). In a Norwegian study, a trained test panel conducted sensory tests of carrots with different levels of carrot psyllid damage (Seljåsen et al. 2006). They found that plants with heavy attack early in the growth period yielded carrots that had negative taste characteristics, including bitterness and astringency, and that the carrots were tough and lacking crispness.


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Fig. 2. Leaf curling caused by the carrot psyllid. The leaflets at the top are mostly unaffected. Photo: Bioforsk The females place the eggs in the leaf tissue, protruding from the edges of the leaves (fig.3). The nymphs continue the feeding process through 5 stages which last through most of the summer. The new generation of adults feeds for a period on the carrots before migrating to the winter host. The carrot psyllid is very difficult to control using currently registered insecticides. Growers in Norway have reported poor efficacy when using pyrethroid insecticides against the pest. Although DNA tests have not been able to confirm genetically based resistance (Nordhus et al., 2006), the poor effect seems to indicate that the carrot psyllid has developed resistance against this group of insecticides. This is not unlikely, as evidenced by the development of insecticide resistance in the carrot psyllid's close relative, the pear psyllid (Psylla pyricola) (Burts 1989).


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Fig. 3. Carrot psyllid eggs in leaf and petiole. Photo: Lund University Living or Non-living Mulch Based on reports from the 1930s that sawdust among the plants reduced attack by carrot psyllid (Apsits 1931), studies were conducted in Sweden using different amounts and application intervals of sawdust. The results confirmed the earlier reports, with a great reduction in egg-laying and damage to the plants in all of the treatments with sawdust (Rämert 1993). It appears that the monoterpenes in sawdust from spruce or pine has a repellent and/or confusing effect. Both fresh sawdust and sawdust treated with turpentine or monoterpenes greatly reduced damage to carrots from the carrot psyllid (Nehlin et al. 1994). In a study in Norway in the mid-1990s, carrots were grown either by conventional agronomic practice or in an intercrop or with a mulch of either sawdust or plant material. There was also a treatment combining an intercrop between beds and a sawdust mulch in the beds (fig.4). The results showed a significant reduction in the number of plants with carrot psyllid eggs in all of the treatments with mulch or intercrop (fig. 5). The greatest reduction was in the treatment with intercrop (vetch) between the beds and sawdust in the beds (Aas 2000; Brandsæter et al. 1999).


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Fig. 4. Research plots to compare the attack of carrot psyllid on carrots surrounded by bare soil, intercrop, plant mulch, sawdust mulch or a combination. Photo: Bioforsk Fig. 5. The percentage of plants that had carrot psyllid eggs when grown in bare soil or surrounded by an intercrop of hairy vetch or with mulch. (Source: Aas 2000)


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Crop Covers The most effective and most commonly used non-chemical method to control carrot psyllid and other insect pests of carrot is to cover the crop with insect net or other covers. Because of the psyllid's small size the netting must have a fine mesh. If the crop is covered from emergence until the main flight period is done, the carrots should be well protected from attack. When applying the netting at emergence it is important that the carrots are sown in depressions of at least 5 cm so the newly emerged plants are not physically damaged by contact with the net. One problem with this method is the extra labor and exposure to attack when removing the covers to allow for mechanical weed control (herbicides can be applied through the netting). Another problem is the change in microclimate, with both higher humidity and higher temperature. The higher humidity encourages plant diseases. The higher temperatures (as high as 64° C has been recorded) cause physiological disorders and negatively affect the quality of the crop. Exclusion Fences Fences made of insect netting have been successful in keeping some insect pests out of vegetable fields. This method was developed especially for low-flying insects such as cabbage and turnip root flies (Delia spp.)(Meadow & Johansen 2005). Kristoffersen and Anderbrant (2007) found adult carrot psyllids up to a height of 4 meters above the ground in spruce trees. In Rygg's studies (1977), there were only small differences between traps 8 cm or 70 cm above the ground in numbers of adult carrot psyllids migrating into the field. Both of these studies tend to negate the probability of fences being effective to keep carrot psyllids out of carrot fields. A netting impregnated with insecticide, currently in use worldwide for protection from and control of mosquitoes, has been developed to protect vegetable crops from insect pests (fig. 6). Produced by Vestergaard-Fransen under the tradename Fence®, the netting is intended to both exclude certain insect pests and through its attractive color and insecticidal effect, it reduces the pest population by way of "trap and kill". This type of fence might be a tool in an integrated strategy against the carrot psyllid.


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Fig. 6. Exclusion fence with attractive color and impregnated with insecticide. Photo: Bioforsk Monitoring Monitoring is an important tool to give the grower information on the time of attack. In the case of the carrot psyllid it is the adult migration from the winter host to the summer host that is crucial. If the grower has an insecticide to use, it should be applied in time to control the adults before they feed on the carrot plants. By the same token, if the grower is using insect net or other covers it is important to cover the plants before invasion and also to know when it is safe to remove the covers. The carrot psyllid is currently monitored using the same yellow sticky-traps (fig. 7) as are used for carrot fly (Psila rosae). No studies have been done to test the optimal color or optimal placement of these traps. A study in Finland where the crop was exposed to carrot psyllid attack at different times in the flight period, to give different attack levels, concluded that one carrot psyllid adult per trap (5 traps per hectare) was correlated with economic damage (Tiilikkala et al. 1996). Researchers in Switzerland currently use the yellow sticky-traps in an extension strategy to indicate when the first adult carrot psyllids come into the field. The growers are informed at the start of the attack and follow up by observing 20 plants at 10 reference points in the field for curling damage (Fischer & Terrettaz 2002; S. Fischer pers. comm.). These observations are compared to treatment thresholds to determine whether or not to apply insecticide.


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Fig. 7. Yellow sticky trap for monitoring flight activity of the carrot psyllid. The vials near the top of the post are experimental dispensers for attractants. Photo: GA-FA Vestfold To inrease monitoring efficiency, research has been done to identify the plant components that are attractive to the carrot psyllid. Swedish studies found two components that were present in high amounts in attractive plant species, sabinene and alpha-pinene (Nehlin et al 1996). They also found that species with high amounts of another component, limonene, were very unattractive to adults of the carrot psyllid. The attractive components have since been studied to enhance trapping, but so far without success. The unattractive components have been tested for repellent effect which appears to reduce attack when applied in high amounts (Nehlin et al. 1994). It is likely that the repellent effect is due to the predominance of these compounds in the winter host, spruce. Since the adults have received cues to leave the spruce and seek out carrot, it is reasonable to conclude that they are repelled by the odor of the winter host. Future Prospects Because the carrot psyllid is a pest of a small crop there is little (or no) investment by international pesticide companies to find insecticides for this pest, neither chemical compounds nor biological control agents. There are few closely related pest species on closely related crops, so the possibilities for off-label registration of insecticides against carrot psyllid are also very limited. Since damage is initiated by attack of overwintered adults on small plants, an insecticidal control has to be quick acting. The most likely candidates should have a contact effect and/or be systemic in the plant, since the psyllid feeds from the plant phloem. Of the synthetic insecticides, ones with new chemistries will help avoid problems with resistance. Spirotetramat (trade name Movento) is one such insecticide that has a good effect against sucking insects, including psyllids (Brück et al. 2009).


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Biological control agents will probably have most effect against the nymphs of carrot psyllid. Their biggest contribution in a management strategi will likely be to reduce populations in a region to improve the situation for the following year. A strain of the insect pathogenic fungus Paecilomyces (=Isaria) fumosorosea has been shown to have a good effect against the Asian citrus psyllid Diaphorina citri, a major pest of citrus that has threatened the Florida citrus industry (Avery et al. 2009; Hoy et al. 2010). P. fumosorosea non-specific and is also native to Norway, so this fungus could be a candidate for further investigation as a tool in an integrated management program. As this report has shown, much research remains to be done to have a better understanding of the biology and behavior of the carrot psyllid in order to develop an effective management strategy. In terms of more basic research, we need to investigate the response of the carrot psyllid to plant odors and pheromones. Finding the most attractive odors will provide a tool for monitoring, trap-and-kill and push-pull strategies. Further studies on repellant odors such as the monoterpenes, will help us to keep the carrot psyllid from finding the carrot host plants and can also be utilized in push-pull strategies. Studies on the carrot psyllid's migration behavior will shed light on the alternative hosts that it utilizes after leaving the winter host (spruce) until it arrives on the summer host (carrot). This knowledge will provide the opportunity to monitor the pest before it begins feeding on the crop and give the growers time to protect the crop. Applied research also needs to be done. Methods need to be developed for protecting the crop from attack, including directly reducing the population of the carrot psyllid. New insecticides need to be tested for their effect on controlling this pest. Biological control agents should be included in such tests. Ways to physically prevent the psyllid from reaching the plants, such as exclusion fences, should be further studied. Dependable methods, such as crop covers of insect netting need to be optimized to give maximum protection without undue negative effects on crop quality. References cited Aas, T. 2000. Soil cover of living and dead plant material against the carrot psyllid. M.sc.

Thesis. The Agricultural University of Norway 69 pp. Apsits, J. 1931. Emploi du papier-carton et de la sciure de bois comme couverture du sol

pour remplacer les binages. Annales Agronomiques 1: 467-494. Avery, P.B., Hunter, W.B., Hall, D.G., Jackson, M.A., Powell, C.A. & Rogers, M.E. 2009.

Diaphora citri (Hemiptera: Psyllidae) infection and dissemination of the entomopathogenic fungus Isaria fumosorosea (Hypocreales: Cordyciptaceae) under laboratory conditions. Florida Entomologist 92: 608-618.

Brandsæter, L. O., Meadow, R., Ugland, A. & Aas, T. 1999. Jorddekking i gulrot. Grønn forskning 4: 109-112.

Brück, E., Elbert, A., Fischer, R., Krueger, S., Kühnhold, J., Klueken, A.M., Nauen, R., Niebes, J.-F., Reckmann, U., Schnorbach, H.-J., Steffens, R. & van Waetermuelen, X. 2009. Movento®, an innovative ambimobile insecticide for sucking insect pest control in agriculture: Biological profile and field performance. Crop Protection 28: 838-844.

Burkhardt, D. & Freuler, J. 2000. Jumping plant-lice (Hemiptera: Psylloidea) from sticky traps in carrot field in Valais, Switzerland. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 73: 191-209.

Burts, E.C. 1989. Pyrethroid resistance in pear psylla, Psylla pyricola Förster (Homoptera: Psyllidae), and synergism of pyrethroids with piperonyl butoxide. The Canadian Entomologist 121: 219-223.


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Fischer, S. & Terrettaz, C. 2003. A strategy for the control of carrot psylla (Trioza apicalis Förster) in Switzerland. IOBC/WRPS Bulletin 26: 331-338.

Hodkinson, I.D. 1974. The biology of the Psylloidea (Homoptera): a review. Bulletin of Entomological Research 64: 325-339.

Hoy, M.A., Singh, R. & Rogers, M.E. 2010. Evaluation of a novel isolate of Isaria fumoserosea for control of the Asian citrus psyllid, Diaphorina citri (Homoptera: Psyllidae). Florida Entomologist 93: 24-32.

Kristoffersen, L. & Anderbrant, O. 2007. Carrot psyllid (Trioza apicalis) winter habitats - insights in shelter plant preference and migratory capacity. Journal of Applied Entomology 131(3): 174-178.

Láska, P. 1974. Studie über den Möhrenblattfloh (Trioza apicalis Först)(Triozidae, Homoptera). Acta Sc. Nat. Brno 8(1): 1-44.

Markkula, M. and S. Laurema 1971. Phytotoxaemia caused by Trioza apicalis Forst. (Hom., Triozidae) on carrot. Annales Agriculturae Fenniae 10: 181-184.

Meadow, R. & Johansen, T.J. 2005. Exclusion fences against Brassica root flies (Delia radicum and D. floralis). IOBC/WPRS Bulletin 28: 39-43.

Munyaneza, J.E., Fisher, T., Sengoda, V.G., Garczynski, S.F., Nissinen, A. & Lemmetty, A. 2010. Association of "Candidatus Liberibacter solanacearum" with the psyllid, Trioza apicalis (Hemiptera: Triozidae) in Europe. Journal of Economic Entomology 103(4): 1060-1070.

Nehlin, G., Valterová, I. & Borg-Karlson, A.-K. 1994. Use of conifer volatiles to reduce injury caused by carrot psyllid, Trioza apicalis, Förster (Homoptera, Psylloidea). Journal of Chemical Ecology 20: 771-783.

Nehlin, G., Valterová, I. & Borg-Karlson, A.-K. 1996. Monoterpenes released from Apiaceae and the egg-laying preferences of the carrot psyllid, Trioza apicalis. Entomologia Experimentalis et Applicata. 80: 83-86.

Nissinen, A., P. Vanhala, J. K. Holopainen & K. Tiilikkala 2007. Short feeding period of carrot psyllid (Trioza apicalis) females at early growth stages of carrot reduces yield and causes leaf discolouration. Entomologia Experimentalis et Applicata 125(3): 277-283.

Nordhus, E., Andersen, A., Meadow, R., Trandem, N. & Johansen, N. 2006. Resistens mot skadedyrmidler stadig mer utbredt. Gartneryrket 4: 23-28.

Rämert, B. 1993. Sawdust can be used for control of the carrot psyllid (Trioza apicalis). Vaxtskyddsnotiser 57(2): 34-38.

Rygg, T. 1977. Biological investigations on the carrot psyllid Trioza apicalis Förster (Homoptera, Triozidae). Scientific Reports of the Agricultural University of Norway 56(3): 1-19.

Seljåsen, R. Høgetveit, L.A., Tajet, T., Bengtsson, G. & Meadow, R. 2006. Effekt av gulrotsuger (Trioza apicalis) på sensorisk kvalitet i gulrot. Bioforsk Fokus 1(3): 90-91.

Tiilikkala, K., Ketola, J. & Taivalmaa, 1996. Monitoring and threshold values for control of the carrot psyllid. IOBC/WRPS Bulletin 19(11): 18-24.

Valterová, I., Nehlin, G. & Borg-Karlson, A.-K. 1997 Host plant chemistry and preferences in egg-laying Trioza apicalis (Hemiptera, Psylloidea). Biochem. Syst. Ecol. 25: 477-491.

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The carrot psyllid, Trioza apicalis biology and control psyllid BIOFORSK RAPPORT… · The carrot psyllid, Trioza apicalis - biology and control ... Carrot psyllid, Trioza apicalis