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Response by Lygus hesperus (Hemiptera: Mirdae) Adults to Salivary Preconditioning of Cotton Squares

Cooper, W. Rodney, Spurgeon, Dale W.
Journal of Entomological Science 2013 v.48 no.3 pp. 261
Gossypium hirsutum, Helianthus annuus, Hemiptera, Lygus hesperus, Phaseolus vulgaris, adults, buds, cotton, feeding preferences, green beans, hosts, indigenous species, insect pests, laboratory rearing, plant tissues, pods, polygalacturonase, saliva, stylets, sunflower seed
Despite being an important pest of fruit, vegetable and field crops in the western United States, many aspects of Lygus hesperus Knight (Hemiptera: Miridae) feeding behavior are poorly understood. Lygus hesperus use a cell-rupture feeding strategy. The insects lacerate and macerate host tissues by vigorous movements of the stylets and discharge of lytic salivary enzymes such as polygalacturonases, then ingest the liquified products (Backus et al. 2007, Ann. Entomol. Soc. Am. 100:296-310). The salivary polygalacturonases of L. hesperus are resilient and remain active in host tissues long after the cessation of feeding (Strong and Kruitwagen 1968, J. Insect Physiol. 14: 1113-1119). Because salivary enzymes continue to digest plant tissues after a feeding event, in may be beneficial for L. hesperus to return to feeding locations that have been preconditioned by salivary enzymes discharged during earier stylet-probing activities. We have observed adult L. hesperus revisiting previously inhabited floral buds (squares) on caged cotton (Gossypium hirsutum L.) plants (WRC, personal observations), but we did not specifically assess feeding behaviours in relation to previous sytlet-probing activities. A better understanding of the influence of slaivary preconditioning on L. hesperus feeding preference could facilitate interpretation of results from assays investigating Lygus feeding injury. The purpose of our study was to investigate whether L. hesperus adults exhibit a preference for squares that are preconditioned by prior stylet-probing activities, compared with previously unvisited squares. Adult L. hesperus were obtained from a laboratory colony maintained on green bean pods (Phaseolus vulgaris L.) and raw sunflower seeds (Helianthus annuus L.). Laboratory rearing results in relatively rapid changes in L. hesperus physioloyg and behavior, compared with native insects (Spurgeon 2012, Environ, Entomol. 41:415-419).