Genetic basis of a specific resistance to malathion in the Australian sheep blow fly, Lucilia cuprina (Diptera: Calliphoridae)

Specific resistance to the organophosphorus insecticide malathion in the RM strain of the Australian sheep blow fly, Lucilia cuprina (Wiedemann), is controlled by an incompletely dominant gene on chromosome 4. This gene, R sub(MAL), was shown to be 24.5 plus or minus 1.3 map units from the visible marker gene sv. However, an allelism test showed that the two genes were closely linked but independent of each other on chromosome 4. Malathion-specific resistance was also shown to be associated with high eterase activity. No significant recombination could be detected between R sub(MAL) and a single locus controlling high esterase activity, suggesting that malathion resistance is derived from enhanced esteratic metabolism of the insecticide.