Structure-Activity Study with Haloalkane Attractants of Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae Using a Behavioral Bioassay

Abstract

A two-choice laboratory behavioral bioassay was used to compare the dose-dependent responses of second-instar western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae to a series of structurally-related haloalkanes, including ones with different halogens, degree of halogen substitution, chain length, and degree of saturation. Disubstituted bromine and iodine analogs of dichloromethane attracted larvae at all doses tested, including 0.5, 1.0, 2.0, and 4.0 mg. Dibromomethane attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). Analogs of dichloromethane with more chlorine substitutions attracted significantly fewer larvae than dichloromethane at most doses tested except for chloroform, which attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). Although larvae were repelled by the two highest doses of 1,1-dichlorobutane tested (2.0 and 4.0 mg), orthogonal contrasts revealed no trend in responses of larvae to increasing doses of it or any of the other chain length analogs tested, 1,1-dichloroethene is an unsaturated analog of 1,1-dichloroethane, and orthogonal contrasts revealed a positive linear trend for responses of larvae to increasing doses of it.