Functional expression of insecticide-resistant GABA receptors from the mosquito Aedes aegypti.

We are interested in cloning insecticide resistance genes from vector mosquitos for use as selectable markers in their genetic transformation. As a first step towards this goal, we here report the functional homomultimeric expression of a gamma-aminobutyric acid (GABA) receptor subunit gene, Resistance to dieldrin (Rdl), from the yellow fever mosquito Aedes aegypti in baculovirus-infected insect cell lines. Replacement of alanine296 with a serine leads to approximately 100-fold insensitivity to picrotoxin as previously observed in Drosophila. This shows not only that the mosquito GABA receptor cDNA is functional but also that it can be simply mutated to resistance. Strategies for incorporation of this cDNA into a minigene for the genetic transformation of mosquitoes are discussed.