Predatory Efficiency and Developmental Attributes of Harmonia dimidiata (Fabricius) (Coleoptera:Coccinellidae) in Relation to Prey Density

The predatory efficiency and survival of immature stages of an aphidophagous ladybeetle, Harmonia dimidiata (Fabricius) were investigated at five different prey densities, viz. , 25, 50, 75, 100 and 125 using Cervaphis quercus Takahashi as prey. A substantial influence of prey density on the rate of larval growth and development was observed. Increased prey density reduced the developmental period. The study also revealed that larval development could be completed at the lowest prey density of 25 prey aphids. The analysis revealed a positive correlation between survival of developmental stages and density of prey provided. A relative increase in weight was observed with increasing density of aphid prey, but only up to a prey density of 100. The functional response exhibited by fourth instar larva exemplified type II predatory response with optimum response at a prey density of 100.