WILSON, T.G.; ASHOK, M.; PURSLEY, S.; Ohio State University, Columbus OH; Colorado State University, Fort Collins: Response of Drosophila melanogaster to insect growth regulator insecticides

Although Drosophila melanogaster is not a pest insect, studies of field populations demonstrate that this insect responds to insecticide usage by evolving resistance. We have studied resistance to the insect growth regulator insecticide methoprene in these flies to understand the genetic basis for resistance. Mutants of the Methoprene-tolerant (Met) gene show resistance to both juvenile hormone (JH) and methoprene. Our previous biochemical studies have demonstrated a mechanism of resistance involving an intracellular JH binding protein with reduced ligand affinity, suggesting that Met is a component of a JH receptor. Met expression results in two transcripts, whose levels were reduced in several Met alleles, including a null, Met27 . The phenotype of Met27 is obvious only as reduced oogenesis, a juvenile hormone-controlled process, suggesting genetic redundancy. Overexpression of Met+ results in increased sensitivity to methoprene, but no other obvious phenotype. Antibody specific for MET localized it in the nuclei of cells of various tissues in all stages of development. Some of these tissues are demonstrated JH target tissues (male accessory gland; ovary), while others are not (early embryo). Sequence analysis showed Met to be a member of the bHLH-PAS family of transcriptional regulators. Met cloned from D. virilis and the mosquito Anopheles gambiae show conservation of bHLH and PAS domains as well as two other gene regions with unknown function.