Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: March 1, 1997
Publication Date: N/A
Interpretive Summary: The tobacco budworm, Heliothis virescens (F.) and bollworm, Helicoverpa zea (Boddie) are economically important insect pests of cotton in the United States and account for a large percentage of insecticides used for cotton production. The tobacco budworm has developed resistance to all classes of conventional insecticides used for its control. In 1996, high and intermediate levels of resistance were found to pyrethroid and carbamate insecticides, respectively, in tobacco budworm; however, no resistance was detected in bollworm. Prior to 1996 the bollworm was found to be resistant to many insecticides and pre-1996 data suggest some evidence for resistance to pyrethroids. Resistance evaluation and monitoring for both pests should continue and efforts to adapt and modify control strategies should be considered. Biological insecticides and other alternative strategies are needed for control of these pests.
Technical Abstract: Strains of the tobacco budworm, Heliothis virescens (F.), and bollworm, Helicoverpa zea (Boddie), collected in Mississippi were evaluated in bioassays to four classes of insecticides, and mixtures of insecticides and a synergist. High and intermediate levels of resistance were found to cypermethrin and thiodicarb, respectively, in H. virescens. No increased tolerance was seen to profenofos in H. virescens and no increased tolerance to any insecticide tested was detected in h. zea. Significant resistance to Bacillus thuringiensis Berliner was not observed in either species during the season. No synergism was detected in a bioassay using insecticide mixtures and piperonyl butoxide on a resistant strain of H. virescens. Multiple resistance in H. virescens is still evident and resistance to pyrethroids appears to be stabilized.