QUANTITATIVE GENETICS OF BEHAVIORAL AND PHYSIOLOGICAL-RESPONSE TO PERMETHRIN IN DIAMONDBACK MOTH (LEPIDOPTERA, PLUTELLIDAE)

Insects may survive insecticide applications by physiological mechanisms that permit tolerance of an acquired dose or behavioral mechanisms that reduce the dose acquired. We investigated the genetic basis of physiological and behavioral responses to the pyrethroid permethrin within four diamondback moth, Plutella xylostella (L.), populations with different average levels of tolerance. Using a half-sib design, variance components and heritabilities of the two characters and the genetic correlation between them were calculated for each population. In all four populations, additive genetic variances and heritabilities for physiological tolerance to permethrin were highly significant. In contrast, heritabilities for behavioral avoidance of permethrin were low and significant in only one population, although additive genetic variances were similar to those for tolerance. The phenotypic and genetic correlations between these two characters varied among the populations from essentially zero to strongly significant. All correlations were negative in form, with behaviorally responsive families tending to be less physiologically tolerant and unresponsive families tending to be more physiologically tolerant. The magnitude of the correlation was related to the amount of additive variation in the population; significant correlations between physiological tolerance and behavioral avoidance occurred in populations with relatively high levels of additive variation for both characters. Implications for the evolution of insecticide resistance and applications for resistance management are discussed, as are parallels with oviposition preference-larval performance studies.