The Effects of Insecticides on Squash Bug, its Egg Parasitoids and Pollinators in Virginia Cucurbit Production

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dc.contributor.authorWilson, James M.en
dc.contributor.committeechairKuhar, Thomas P.en
dc.contributor.committeechairAnderson, Troy D.en
dc.contributor.committeememberHerbert, D. Ames Jr.en
dc.contributor.committeememberPfeiffer, Douglas G.en
dc.contributor.committeememberAdams, James Clevelanden
dc.contributor.departmentEntomologyen
dc.date.accessioned2018-07-28T06:00:26Zen
dc.date.available2018-07-28T06:00:26Zen
dc.date.issued2017-02-02en
dc.description.abstractMy dissertation and research focused on the effects of insecticides on squash bugs, its egg parasitoid, and pollinators in the production of cucurbits in Virginia. Plants in the cucumber family are dependent on insect pollination for successful fruit set, and are also susceptible to plant eating insects. Squash bugs are capable of transmitting cucurbit yellow vine decline, and their feeding can cause significant wilt and death in many varieties. To control for squash bug and other pests, growers commonly combine the application of broad-spectrum insecticides with the frequently applied prophylactic fungicides. Broad-spectrum insecticide applications are known to have negative effects on natural enemy populations, are capable of promoting insecticide resistance, and can have negative effects on pollinators if care in their use is not taken. Squash bugs have several natural enemies, but their predominant egg parasitoid is most effective at reducing damaging populations. The scelionid wasp Gryon pennsylvanicum Ashmead, is a prevalent egg parasitoid in Virginia and can be negatively affected by the application of broad-spectrum insecticides. Through survey efforts I found that G. pennsylvanicum is widely distributed throughout Virginia and is capable of high rates of egg parasitism (>90%). This is contrary to the 20% level previously assumed for the East Coast. I explored the effects of narrow-spectrum insecticides on the fate of the egg parasitoids, those developing in the host egg and emerged adults of G. pennsylvanicum. Contact assays showed that the insecticides λ-cyhalothrin and sulfoxaflor had caused high adult parasitoid mortality. As new insecticides get registered for use there is often concern about their effect on pollinators, specifically the European honey bee Apis mellifera L. I evaluated the use of large flight cages as a method to measure the sub-lethal effects of narrow-spectrum insecticides to honey bees, as a means to qualify risk. The method utilizes small colonies of honey bees (with stores of nectar and pollen) and their feeding at a treated sucrose solution after being trained to a feeder in an enclosed arena. This choice-test style behavioral experiment shows promise in qualifying the risks associated with insecticide exposure in the field. In the case of pyrifluquinazon, colonies repeatedly choose to avoid feeding at tainted feeders even after training with no other outside sources of food present. Further researching the sub-lethal behavioral effects that insecticides have on bees in a colony can help us better qualify their risk.en
dc.description.degreePh. D.en
dc.format.mediumETDen
dc.identifier.othervt_gsexam:9431en
dc.identifier.urihttp://hdl.handle.net/10919/84425en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectCucurbitsen
dc.subjectSquash Bugen
dc.subjectEgg Parasitoidsen
dc.subjectPollinator Risken
dc.titleThe Effects of Insecticides on Squash Bug, its Egg Parasitoids and Pollinators in Virginia Cucurbit Productionen
dc.typeDissertationen
thesis.degree.disciplineEntomologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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