DIRECT AND INDIRECT SELECTION ON BEHAVIORAL-RESPONSE TO PERMETHRIN INLARVAL DIAMONDBACK MOTHS (LEPIDOPTERA, PLUTELLIDAE)

Both physiological tolerance to the pyrethroid permethrin and behavior al response to permethrin have been shown to have some genetic basis i n the diamondback moth, Plutella xylostella (L.). Hence, selection bas ed on these characters should be possible. We investigated the direct and indirect effects of selection on physiological tolerance and behav ioral responsiveness, and how these effects vary across populations. W orking with four populations for which genetic information was availab le, we created three groups within each population by selecting for be havioral responsiveness and unresponsiveness, and by separately select ing for physiological tolerance. Tile effects of selection were evalua ted by assaying the offspring of these groups. In all four populations , the dominant effects of selection were on physiological tolerance. P hysiological tolerance was higher in those groups selected directly ba sed on tolerance, and those selected for behavioral unresponsiveness, than in the groups selected for behavioral responsiveness. In addition , tolerance was higher in the groups selected for tolerance and behavi oral unresponsiveness than in the parental generation in all but one p opulation. We observed no clear patterns with respect to the behaviora l character. Direct selection for responsiveness was successful in onl y one population. Selection based on tolerance did not indirectly prod uce shifts. in behavior. At least two elements of behavior, however we re affected by selection: first, general responsiveness as shown by be havioral variation independent of permethrin; second, an increased ten dency to avoid permethrin especially at high toxin concentrations. The se effects varied among the populations apparently as a result of vari ation in genetic parameters.