Negative correlations between resistance to three organophosphate insecticides and productivity within a natural population of Drosophila melanogaster (Diptera: Drosophilidae)

To investigate the relationship between resistance to organophosphate insecticides and fitness components, we first measured resistance to three organophosphates, malathion, prothiophos. and fenitrothion, and productivity, a measure of fitness components, for each of the isofemale lilies from the same natural population of Drosophila melanogaster (Meigen). Pearson correlation coefficients indicated that positive correlations among resistance to the organophosphates and negative correlations between resistance to each of the organophosphates and the productivity existed within the natural population. We further investigated the genetic basis of the correlations among resistance to the organophosphates and the productivity, by using chromosome-substituted lilies between a resistant and a susceptible inbred line established from the same natural population. Chromosomal analyses indicated that the third chromosome from the resistant line exhibited not only significant, positive effects oil resistance to all of the organophosphates tested but also a significant negative effect on the productivity, suggesting positive genetic correlations between resistance to each organophosphate and negative genetic correlations between resistance to each organophosphate and the productivity. In addition, a significant negative effect oil the productivity was also detected from the second chromosome, which did not exhibit significant major effects oil resistance to the organophosphates within the natural population of D. melanogaster are discussed from the standpoint of negative genetic correlations between resistance to the organophosphates and the productivity.