Esterases de zaprionus indianus gupta, 1970 (diptera: drosophilidae): biomarcadores para a contaminação por malathion?

Abstract

Zaprionus indianus is a drosophilid of African origin wich the first report in the Brazilian territory date from 1999 in the state of São Paulo, infesting persimmon and fig fruits. Subsequently the fly quickly reached plague status. One of the ways farmers used to control Z.indianus is chemical management, which may culminate in the evolution of insecticide resistance processes by the pest. A widely used organophosphate is malathion. Some genes and their protein products are related to organophosphate resistance to insecticides such as esterases, and Z.indianus carries these genes. This study aimed to evaluate a possible bioindicator role of esterases EST2, EST3 and EST6 in environments exposed to insecticides. Bioassays were performed with individuals exposed to the malathion insecticide and also polyacrylamide gel electrophoresis to determine enzymatic polymorphisms and acetylcholinesterase activity. Bioassay analyzes show high female mortality when treated with the insecticide and esterase polymorphisms show a loss of heterozygosity in the insecticide treated populations and an increased frequency of the Est33 and Est2F allele in insecticide treated populations. Results for EST6 activity show a decrease in the activity of these esterase in populations exposed to organophosphate. Thus, Z.indianus esterases can play a large role as bioindicators in insecticide-exposed environments.