GENETIC-VARIATION AT THE PGI LOCUS IN THE MOSQUITO FISH GAMBUSIA-AFFINIS (POECILIDAE) AND A POSSIBLE EFFECT ON SUSCEPTIBILITY TO AN INSECTICIDE

Although some studies have been completed on genetic variation in relation to tolerance to heavy metals, none have considered pesticide pollution. This study examines the relationship between genotypes at the glucose phosphate isomerase (Pgi) locus in Gambusia and susceptibility to the organophosphate insecticide chlorpyrifos. Laboratory toxicity tests show significant differences in genotype frequencies between susceptible and tolerant groups offish from one site but not at others. A field survey examined genotype frequencies and levels of pesticide in the fish at seven sites. No chlorpyrifos was found at any of the sites, but a number of organochlorines were recorded. Significant correlations were found between three organochlorines (DDT/DDD, DDE and lindane) and frequences of particular genotypes. There were also significant differences in tolerance between populations and between size classes. These results are discussed in relation to previous work with heavy metals. Copyright © 1991, Wiley Blackwell. All rights reserved