Lhb. Kanga et al., TOLERANCE TO CYPERMETHRIN AND ENDOSULFAN IN-FIELD POPULATIONS OF THE BOLLWORM (LEPIDOPTERA, NOCTUIDAE) FROM TEXAS, Journal of economic entomology, 89(3), 1996, pp. 583-589
Responses to insecticides in bollworm, Helicoverpa tea (Boddie), males
collected from 1988 to 1994 in sex-pheromone baited traps in the Braz
os Valley near College Station, TX, varied during each season with tol
erance being highest in midseason. Significant tolerance occurred with
cypermethrin in 1988 and 1989, and with endosulfan in 1994. Tests in
1994 with profenofos or methomyl showed no significant tolerance to th
ese insecticides. We found significant variations between trap sites i
n responses of field bollworms to cypermethrin, suggesting that increa
sed tolerance may be a localized phenomenon. Tests with cypermethrin p
lus piperonyl butoxide indicated significant synergism in bollworms co
llected from the field, suggesting that enhanced metabolic degradation
may be a factor in pyrethroid tolerance in this species. Diagnostic c
oncentrations for monitoring tolerance in field-collected bollworm mal
es were determined for all insecticides tested, The results reported h
ere validate use of the adult vial test to monitor for tolerance to in
secticides in the bollworm, and provide information useful for the dev
elopment of a resistance management strategy intended to extend the ef
ficacy of insecticides used to control the bollworm.