Abstract
1. The first-(after hatching), the second-(about 35 hours after hatching), and the mature third-(about 96 hours after hatching) instar larvae of insecticide-resistant strains (Hikone and WMB) and insecticide-susceptible strains (Fukuoka and Canton-S) of D. melanogaster were raised in the foods containing parathion in various concentrations, to investigate the effects of parathion on their pupation and emergence.
2. In the first-instar larvae of Fukuoka and Canton-S strains. their pupation rates and the emergence rates were decreased to 4% and 1%, respectively, by 0.1ppm parathion. The first-instar larvae of Hikone and WMB strains, their pupation rates were decreased to 35% and 26%, respectively, by 3.0ppm parathion, and the emergence rates were decreased to 34% and 26%, respectively, by 3.0ppm parathion.
3. In the second-instar larvae of Fukuoka and Canton-S strains, their pupation and emergencies were completely inhibited by 0.1ppm parathion. In the second-instar larvae of Hikone and WMB strains, their, pupation rates were decreased to 27% and 14%, respectively, by 3.0ppm parathion, and the emergence rates were decreased to 26% and 14%, respectively, by 3.0ppm parathion.
4. In the mature third-instar larvae of Fukuoka and Canton-S strains, their pupation rates were decreased to 21% and 39%, respectively, by 50.0ppm parathion, and the emergencies were completely inhibited by 50.0ppm parathion. In the mature third-instar larvae of Hikone and WMB strains, their pupation rates were decreased to 21% and 19% respectively, by 50.0ppm parathion, and the emergence rates of the both strains were decreased to 3% by 50.0ppm parathion.
5. In the case of the first-and second-instar lavae, a slight difference between the lengths of the larval periods of the resistant strains and those of the susceptible strains was found, but no significant difference between the lengths of the pupal periods of the resistant strains and those of the susceptible strains was found.
