Abstract
A housefly (Musca domestica L.) strain highly resistant to pyriproxyfen, a juvenile hormone analog, was established by laboratory selection of houseflies collected from the 3rd Yumenoshima dumping-island in Tokyo Bay, Japan. the strain developed 4, 900-fold resistance to pyriproxyfen in the 3rd instar larvae by the 17th generation from a level of only 3.8-fold before selection and thus was named YPPF strain. Genetic analysis of pyriproxyfen resistance in YPPF houseflies revealed that resistance to pyriproxyfen in this strain was incompletely dominant and multifactorial. There were at least 4 dominant factors responsible for the resistance, with the most important factor being located on the 2nd chromosome and other factors on the 1st, 3rd and 5th chromosomes. Furthermore, bioassay of synergism showed that the resistance ratio in white pupae of houseflies was depressed to 29-fold from 400-fold by a cytochrome P450 inhibitor, 2-propynyl 2, 3, 6-trichlorophenyl ether (PTPE). These results indicate that P450 monoxygenase plays an important role in housefly resistance to pyriproxyfen.
