Characterization of cytochrome P450 forms CYP6H2, CYP6B6 and CYP6B7 in pyrethroid resistant strains of the lepidopteran, helicoverpa armigera

Abstract

Three cDNAs encoding CYP6B2 CYP6B6 AND CYP6B7 for the insect t II. armigera cotton bollowrm j have been isolated. The sequences show between 80 and 90% identity, with the sequences indicating a recent partical gene c onversion event between CYP6B2 and CYP6B6, CYP6B7 is highly inducible b by treatment of larvae with menolerpenes as well as being slightly inducible b by non toxic levels of the pvrethroid, permethrin. In addition this from is overexpressed in field collected larvae which show resistance to pyrehroid insecticides. We are undertaking a number of experimental pproaches to rpve our hypothesis that overexpession of this from does in fact cause pyrethroud resistance, We have isolated a number of genomic clones containing the genes for these proteins. The genes encoding all the three enzymes occur as a closely linked group within the getome. At Present we are characterizing the promoter regions of these genes in order to understand the mechanism involved in overproduction of CYP6B7 and how this is related to insecticide resistance in this species. Show more