Inheritance mode, cross-resistance and realized heritability of pyriproxyfen resistance in a field strain of Musca domestica L. (Diptera: Muscidae).

Pyriproxyfen is a growth regulator used for the control of different insect pests, including Musca domestica. To assess the risk of resistance and to develop a strategy for resistance management, a field strain of M. domestica was exposed to pyriproxyfen in the laboratory for 30 generations. The inheritance mode, realized heritability of pyriproxyfen resistance and cross-resistance to other insecticides were assessed. Prior to the selection process, the field strain exhibited a resistance ratio (RR) of 25.7, 7.31, 7.67, and 27-fold for pyriproxyfen, methoxyfenozide, cyromazine and lufenuron, respectively, when compared to the pyriproxyfen susceptible strain (Pyri-Sus). After continuous selection with pyriproxyfen, the pyriproxyfen-resistant strain (Pyri-Res) became 206-fold more resistant than the Pyri-Sus strain. The overlapping confidence limits of LC50 values of F1 (Pyri-Res ♂×Pyri-Sus ♀) and F1(†) (Pyri-Res ♀×Pyri-Sus ♂) suggested an autosomal and completely dominant mode of resistance to pyriproxyfen. Monogenic test of inheritance showed that resistance to pyriproxyfen was governed by multiple genes. The Pyri-Res strain showed very low cross resistance to methoxyfenozide, cyromazine, and lufenuron. The estimated realized heritability was 0.02, 0.05, 0.03 and 0.04 for pyriproxyfen, methoxyfenozide, cyromazine, and lufenuron, respectively. It was concluded that pyriproxyfen resistance in M. domestica was autosomally inherited, completely dominant and polygenic. These results would be helpful for the design of an improved control strategy against M. domestica.