Advisor

Gore, Jeffrey

Committee Member

Musser, Fred R.

Committee Member

Catchot, Angus L.

Committee Member

Cook, Donald R.

Committee Member

Dodds, Darrin M.

Date of Degree

8-1-2020

Document Type

Graduate Thesis - Open Access

Abstract

The bollworm, Helicoverpa zea (Boddie), is an economically important pest of cotton and is becoming more difficult to control in the United States. This project was designed to develop a better understanding of the effects of resistance development and plant structures on the efficacy of Bt cotton and foliar insecticides. Experiments examined larval behavior and damage in current cotton varieties expressing proteins from Bacillus thuringiensis. Other experiments examined the effects of floral structures on the control of bollworm using foliar insecticides. Results suggest that larval feeding and avoidance behavior is dependent on point of eclosion. Fruiting form damage increased in two-gene cotton compared to earlier research but was low in cotton expressing the Vip3A protein. Increases in damage can lead to more frequent applications of foliar insecticides. Floral structures can hinder insecticide efficacy by reducing exposure. Results from these experiments will be important for refining management recommendations for bollworm in Bt cotton.

URI

https://hdl.handle.net/11668/18424

Sponsorship

Cotton Incorporated United States Department of Agriculture

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