Genetic Basis of Resistance to Diazinon in Victorian Populations of the Australian Sheep Blowfly, Lucilia Cuprina

Populations of L. cuprina from the Baimsdale, Glenrowan, Hamilton and Torrita areas of Victoria were found to have similar high diazinon resistance status, following near fixation of a single allele at the Rl locus. Pure-breeding resistant strains were derived from each area and used as base populations for a selection program on adults. An approximate doubling of the level of resistance to diazinon was achieved in each strain after eight generations of selection. Relaxation of selection over seven generations showed the response had generated a stable plateau in all but the Torrita selected strain, which regressed towards the resistance level of the original base population.