Flight Behavior of Methyl-Parathion-Resistant and â•fiSusceptible Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations from Nebraska

Relative ßight behavior of methyl-parathion-resistant and -susceptible western corn rootworm,Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced actograph was used to compare ßight of resistant and susceptible individuals, and ßight of resistant individuals with and without prior exposure tomethyl-parathion. In each case,mean trivial and sustainedßight durationswere compared among treatments. In general, there were few differences in trivial or sustained ßight characteristics as affected by beetle population, insecticide exposure, sex, or age and there were few signiÞcant interactions among variables. Tethered ßight activity was highly variable and distributions of ßight duration were skewed toward ßights of short duration. Tethered ßight activity was similar among resistant and susceptible beetles with the exception that susceptible beetles initiated more ßights per beetle than resistantbeetles.After sublethal exposure tomethyl-parathion, total ßight time, total trivial ßight time, andmean number of ßights per resistant beetle declined signiÞcantly. Because long-range ßight was uncommon, shortto medium-duration ßights may play an important role in determining gene ßow and population spread of resistant D. v. virgifera. These results suggest that organophosphate-resistant beetles can readilymove and colonize newareas, but localized selectionpressure (e.g., management practices) and exposure to methyl-parathion may contribute to the small-scale differences in resistance intensity often seen in the Þeld.