Permethrin resistance associated with inherited genes in a near-isogenic line ofMusca domestica

BACKGROUND Permethrin has been used frequently in the control ofMusca domesticaworldwide including Pakistan, with reports of resistance development in different field strains. A near-isogenic line ofM. domesticawith permethrin resistance (Perm-R) was constructed to elucidate mode of inheritance and cross-resistance analyses. RESULTS Toxicity responses of reciprocal progenies F1 and F1 ' showed no significant difference in median lethal dose (LD50) values, suggesting that permethrin resistance was inherited in an autosomal fashion with neither sex linkage nor maternal effects in the Perm-R strain ofM. domestica. Degree of dominance was 0.6 and 0.7 for F1 and F1 ' progenies, respectively, which suggests that permethrin resistance was expressed as an incompletely dominant trait. Chi-square analyses for self-bred (F2), and backcross progenies (BC1, BC2, BC3 and BC4) revealed significant differences between the observed and expected mortality, indicating the possibility of multiple genes responsible for permethrin resistance. Moreover, the Perm-R strain did not show cross-resistance to propoxur, chlorpyrifos, profenofos or spinetoram. CONCLUSION Permethrin resistance in the Perm-R strain ofM. domesticawas inherited as autosomal, incompletely dominant and governed by more than one gene. Lack of cross-resistance between permethrin and propoxur, chlorpyrifos, profenofos or spinetoram provides an opportunity for rotational use of these insecticides in the control ofM. domestica. These data could help to manageM. domesticaand the problem of permethrin resistance.

Automated summary

The study showed that permethrin resistance in the Perm-R strain of M. domestica is inherited as an autosomal trait with incomplete dominance, controlled by multiple genes. Lack of cross-resistance to other insecticides opens up the possibility of rotational use for control of M. domestica.