Location: Pest Management and Biocontrol Research
2016 Annual Report
Accomplishments
1. New mode of action for Bacillus thuringiensis (Bt) toxins discovered. Resistance to Bt transgenic crops is increasing globally, threatening the benefits of these effective and environmentally-friendly crops. An ARS scientist at Maricopa, Arizona, and a team of university collaborators discovered a new model of Bt intoxication (the “dual” model) in which Bt protoxins and activated toxins kill insects via different pathways. The research demonstrated that protoxins killed some Bt resistant insects better than the corresponding activated toxins. This suggests that a previously unknown mode of action for Bt toxins exists and that there may be utility in using protoxins in transgenic Bt crops to enhance and/or sustain their efficacy.
2. Novel method for identifying predators in agroecosystems. Insect predators and spiders provide valuable ecosystem services in agriculture settings, however, identifying the main predators of pests by direct observation is difficult because arthropods are small and elusive. The most popular indirect method to assess predation is by examination of a predator’s stomach contents for the presence of prey-specific DNA, but these assays are complex, expensive, and labor intensive. An ARS scientist in Maricopa, Arizona, has developed an alternative approach that uses generic immunological assays designed to detect unique protein marks applied to the prey and subsequently transferred to the predator during feeding. Research showed that the generic assay was more sensitive and reproducible than the DNA assay for detecting predation while being less expensive and time consuming than the DNA assay. The generic gut assay procedure has been adopted by researchers throughout the world to study various aspects of predation. Using this method to pinpoint the main predators in an agroecosystem setting will lead to better conservation biological control practices.
3. Long-term dynamics of insect parasitoids attacking sweetpotato whitefly. Sweetpotato whiteflies are a pest of global significance and negatively impact many field and horticultural crops. Whiteflies are attacked by a broad range of natural enemies, including insect parasitoids. An ARS scientist in Maricopa, Arizona, conducted a long-term 15-year study to examine interactions between sweetpotato whitefly and several parasitoid species that generally specialize on whiteflies. This time period coincided with a USDA led, large-scale program in conjunction with the Animal and Plant Health Inspection Service (APHIS) to introduce exotic parasitoid species for biological control of sweetpotato whitefly. These introductions dramatically changed the parasitoid species composition in the cotton system by replacing three native species with two exotic species, however, the introductions did not change the levels of parasitism and have thus not contributed to increased biological control of the pest in Arizona cotton. Results are of interest to scientists studying introductory biological control and pest management and should help to inform future large-scale biological control programs.
4. Field validation of insecticide efficacies against Cucurbit Yellow Stunting Disorder Virus (CYSDV) in cantaloupes. Cantaloupe production in the southwestern U.S. has been severely impacted by epidemics of CYSDV since 2006 when it was first detected in Arizona. Infection by CYSDV causes yield reduction and poor fruit quality, especially when plants are infected early in their development. A series of greenhouse tests demonstrated the capacity of certain insecticides to prevent transmission of CYSDV to cantaloupe plants by viruliferous whiteflies. To evaluate their performance in an agricultural setting, ARS scientists in Maricopa, Arizona, conducted field studies on cantaloupes treated with five systemic insecticides. Under heavy whitefly pressure, two of the five insecticides significantly reduced the number of infections and the rate at which they became infected. These findings will provide critical guidance to growers and pest consultants seeking to both reduce and delay the incidence of CYSDV in cantaloupe fields.
5. Transcriptomic analysis of four species of xylem-sap feeding insects. Specialized feeding on nutrient-deficient xylem sap is relatively rare among insect herbivores, and only limited genomic and transcriptomic information has been generated for xylem-sap feeders. Various species of spittle bugs and sharpshooters are well-known xylem-sap feeders and vectors of the bacterium (Xylella fastidiosa) that causes Pierce’s disease in grapevines and other crop diseases. ARS scientists in Maricopa, Arizona, generated transcriptome assemblies for three sharpshooter species and one spittle-bug species for a more comprehensive understanding of biochemical adaptations and symbiotic relationships that support their unique living habits. Information contained in the transcriptomes of the four xylem-sap feeding insects will provide additional knowledge and insight into the survival of ecological specialists on a nutritionally poor dietary source.
Review Publications
Fabrick, J.A., Unnithan, G.C., Yelich, A.J., Degain, B., Masson, L., Zhang, J., Carriere, Y., Tabashnik, B.E. 2015. Multi-toxin resistance enables pink bollworm survival on pyramided Bt cotton. Scientific Reports. 5:16554. doi: 10.1038/srep 16554.
Naranjo, S.E., Li, S. 2016. Long term dynamics of aphelinid parasitoids attacking Bemisia tabaci. Biological Control. 93:56-64.
Tassone, E.E., Geib, S.M., Hall, B., Fabrick, J.A., Brent, C.S., Hull, J.J. 2016. De novo construction of an expanded transcriptome assembly for the western tarnished plant bug, Lygus hesperus. Gigascience. 5:6.
Spurgeon, D.W. 2016. Captures of boll weevils (Coleoptera: Curculionidae) in relation to trap orientation and distance from brush lines. Journal of Economic Entomology. 109(2):676-683. doi: 10.1093/jee/tov392.
Wang, Y., Kaftanoglu, O., Brent, C.S., Page Jr., R.E., Amdam, G.V. 2016. Starvation stress during larval development reveals predictive adaptive response in adult worker honey bees (Apis mellifera). Journal of Experimental Biology. 219:949-959.
Guo, Y., Tian, J., Shi, W., Dong, X., Romeis, J., Naranjo, S.E., Hellmich Ii, R.L., Shelton, A. 2015. The interaction of two-spotted spider mites, Tetranychus urticae Koch, with Cry protein production and predation by Amblyseius andersoni (Chant) in Cry1Ac/Cry2Ab cotton and Cry1F maize. Transgenic Research. 25(1):33-44.
Katayama, Y., Suzuki, T., Ebisawa, T., Ohtsuka, J., Wang, S., Natsume, R., Lo, Y., Senda, T., Nagamine, T., Hull, J.J., Matsumoto, S., Nagasawa, H., Nagata, K., Tanokura, M. 2016. A class-A GPCR solubilized under high hydrostatic pressure retains its ligand binding ability. Biochimica et Biophysica Acta. 1858(9):2145–2151.
Spurgeon, D.W., Brent, C.S. 2015. Diapause response to photoperiod in an Arizona population of Lygus hesperus (Hemiptera: Miridae). Journal of Entomological Science. 50:238-247.
Tassone, E.E., Zastro-Hayes, G., Mathis, J., Nelson, M., Wu, G., Flexner, L.J., Carriere, Y., Tabashnik, B.E., Fabrick, J.A. 2016. Sequencing, de novo assembly, and annotation of a pink bollworm larval midgut transcriptome. Gigascience. 5:28. doi: 10.1186/s13742-016-0130-9.
Hagler, J.R., Tassone, E.E., Coffelt, T., Lipka, A.E. 2016. Host plant preference of Lygus hesperus exposed to three desert-adapted industrial crops. Industrial Crops and Products. 89:363-367. doi: 10.1016/j.indcrop.2016.05.041.
Brent, C.S., Katelyn, M., Connor, V., Brittany, M., Bronwen, S., Brent, K.G., Rachna, N. 2016. Regulatory roles of biogenic amines and juvenile hormone in the reproductive behavior of the western tarnished plant bug (Lygus hesperus). Journal of Comparative Physiology. 186(2):169-179.
Carriere, Y., Fabrick, J.A., Tabashnik, B. 2016. Can pyramids and seed mixtures delay resistance to Bt crops? Trends in Biotechnology. 34(4):291-302. doi: 10.1016/j.tibtech.2015.12.011.
Hagler, J.R., Blackmer, F., Spurgeon, D.W. 2015. Accuracy of a prey-specific DNA assay and a generic prey-immunomarking assay for detecting predation. Methods in Ecology and Evolution. 6(12):1426-1434. doi: 10.1111/2041-210X.12436.
Hagler, J.R., Machtley, S.A. 2016. Administering and detecting protein marks on arthropods for dispersal research. Journal of Visualized Experiments. 107:e53693. doi: 10.3791/53693(2016).
Tabashnik, B.E., Zhang, M., Fabrick, J.A., Wu, Y., Gao, M., Huang, F., Wei, J., Zhang, J., Yelich, A., Unnithan, C., Bravo, A., Soberon, M., Carriere, Y., Li, X. 2015. Dual mode of action of Bt proteins: Protoxin efficacy against resistant insects. Scientific Reports. 5:15107. doi: 10.1038/srep15107.
Blubaugh, C.K., Hagler, J.R., Machtley, S.A., Kaplan, I. 2016. Cover crops increase foraging activity of omnivorous predators in seed patches and facilitate weed biological control. Agriculture, Ecosystems and Environment. 231:264-270.
Brent, C.S., Wang, M., Miao, Y., Hull, J.J. 2016. Ecdysteroid and chitinase fluctuations in the western tarnished plant bug (Lygus hesperus) prior to molt indicate roles in development. Archives of Insect Biochemistry and Physiology. 91(5):108-126.
Hagler, J.R., Blackmer, F. 2015. Evidence of intraguild predation on a key member of the cotton predator complex. FOOD WEBS. 4:8-13.
Zinna, R., Gotoh, H., Brent, C.S., Dolezal, A., Kraus, A., Niimi, T., Emlen, D., Lavine, L. 2016. Endocrine control of exaggerated traits in rhinoceros beetles. Integrative & Comparative Biology. 56(2):247-259.
Fu, T., Hull, J.J., Yang, T., Wang, G.R. 2016. Identification and functional characterization of four TRPA1 variants in Apolygus lucorum (Meyer-Dür). Insect Molecular Biology. 25(4):370–384.
Klick, J., Yang, W., Walton, V., Dalton, D., Hagler, J.R., Dreves, A., Lee, J.C., Bruck, D. 2016. Distribution and activity of Drosophila suzukii in cultivated raspberry and surrounding vegetation. Journal of Applied Entomology. 140:37-46. doi: 10.1111/jen.12234.
Aslimwe, P., Ellsworth, P.C., Naranjo, S.E. 2016. Natural enemy impacts on bemisia tabaci dominate plant quality effects in the cotton system. Ecological Entomology. 41:642-652.
