Effect of temperature on the biology of Harmonia dimidiata FAB. (Coleoptera: coccinellidae) reared on scizaphus graminum (ROND.) aphid

The influence of five constant temperatures (16±1°C, 20±1°C, 24±1°C, 28 ±1°C and 32 ±1°C) on the biology and prey consumption of larvae, adult male and female beetles of the ladybeetle, Harmonia dimidiata (Fab.), (Coccinellidae: Coleoptera), feeding on Schizaphus graminum aphid was investigated. There was significant effect of temperature on the biology and prey consumption potential of immature and adult stages of H. dimidiata. The result revealed that incubation period, different larval instars duration, pupal and adult male and female beetles duration was maximum at the low temperature 16 ± 1˚C and minimum at the high temperature 32 ± 1˚C. The survival rate and predatory potential of all stages was maximum at 24 ± 1 ˚C. The female fecundity was maximum 686.75±18.277 eggs per female at 24 ± 1˚C and minimum 223.75±4.3279t 28 ± 1˚C. The results further revealed that at 32± 1˚C the female could not produce eggs. The result indicates that temperature have profound effect on the developmental durations, survival, fecundity and predatory potential of Harmonia dimidiata. The optimum rearing temperature for this predator was found to be 24 ±1°C on the basis of their short durations, maximum survival and high reproductive and predatory potential of H. dimidiata (Fab.). These attributes may take it a useful natural enemy for the purpose of biological control program against aphid pests of economic importance.