INTERACTION BETWEEN GENOTYPES AT THE DIAZINON-RESISTANCE LOCUS OF THE AUSTRALIAN SHEEP BLOWFLY, LUCILIA CUPRINA....

The survival of larvae with susceptible (+ +) genotypes at the diazinon-resistance locus of the Australian sheep blowfly, Lucilia cuprina is facilitated by prior conditioning of diazinon-containing media by heterozygote (R+) or resistant (RR) larvae. The effect is not observed on media without diazinon. Conditioning by + + genotypes does not affect subsequent development of susceptible larvae and the viability of R + and RR larvae is unaffected by conditioning of the media. Similar results are observed when the medium is conditioned with crushed larvae of the three genotypes. The development of + + larvae is enhanced only on media containing diazinon to which R + or RR crushed larvae are added. The results for other comparisons are equivalent for conditioned or unconditioned media. The number of crushed ++, R +, or RR larvae added to the medium containing diazinon does not affect the proportion of + + eggs that develop through larval and pupal stages to emerge as adults. The rate of development of the + + genotype is, however, positively correlated with the number of crushed R + or RR larvae added.