We compared responses to cotton bolls with and without Bacillus thuringiensis (Bt) toxin Cry1Ac by adult females and neonate larvae from susceptible and resistant strains of pink bollworm, Pectinophora gossypiella. In choice bioassays on caged cotton plants in the greenhouse, neither susceptible nor resistant females laid fewer eggs on Bt cotton bolls than on non-Bt cotton bolls, indicating that the Bt toxin did not deter oviposition. Females laid more eggs per boll on younger and larger bolls. They also laid more eggs per boll on plants with more bolls. The distribution of eggs among bolls was clumped, indicating that boll quality rather than avoidance of previously laid eggs was a primary factor in oviposition preference. Parallel with the results from oviposition experiments, laboratory tests showed that the number of entrance holes per boll did not differ between Bt cotton and non-Bt cotton for susceptible and resistant neonates. Also, like females, neonates preferred younger and larger bolls. Thus, acceptance of bolls by females for oviposition and by neonates for mining was affected by boll size and diameter, but not by Bt toxin in bolls. The lack of discrimination between Bt and non-Bt cotton bolls by ovipositing females and neonates indicates that these host choice behaviors are independent of susceptibility to Cry1Ac.
Species 1: Lepidoptera Gelechiidae Pectinophora gossypiella (pink bollworm)
Keywords: Bacillus thuringiensis, resistance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA