ABSTRACT

Four laboratory, eight laboratory cross and twenty field populations of bollworm (BW), Helicoverpa zea or tobacco budworm (TBW), Heliothis virescens (F.) were assayed for susceptibility to Cry1Ac and Cry2Ab proteins at the University of Arkansas in 2003. The susceptibility of BW to Cry1Ac varied among and between the laboratory, laboratory cross and field populations. In comparison with laboratory susceptible populations, LC₅₀s were 4- to 7-fold higher in colonies collected from conventional crops and 12- to 25-fold higher in colonies collected from Bt crops. Susceptibilities of the laboratory cross and field populations of BW to Cry2Ab were 4- to 18-fold higher than the laboratory susceptible colony. Susceptibilities of field collected noctuids, mirids and pentatomids to acephate, cypermethrin, malathion, spinosad, cyfluthrin and bifenthrin were measured by a treated glass vial technique. Base-line data were established for future references and comparison to first year data reported last year.