Inheritance of dicrotophos resistance in greenhouse whitefly

We studied inheritance of resistance to dicrotophos in greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera, Aleyrodidae). Compared with females from a field‐collected susceptible strains (S), females from a resistant strain (R) of T. vaporariorum derived from heavily treated cotton fields had a 28‐fold greater LC₅₀ to dicrotophos in laboratory bioassays. Concentration‐mortality lines obtained from female progeny of reciprocal F₁ crosses (R♀ XS♂ and S♀ XR♂) were similar, suggesting that inheritance of dicrotophos resistance was autosomal and not influenced by maternal effects. Responses of F₁ female progeny were similar to those of the parental S strain, indicating that the resistance was partially recessive (degree of dominance, D, was −0.61). Mortality observed in female progeny obtained from a backcross (F₁♀ XR♂) corresponded more closely to expectations derived from polygenic models than to expectations from a monogenic model. The estimated number of effective factors (sensu Lande, 1981) contributing equally to resistance was three. 1995 The Netherlands Entomological Society