Intraguild predation of inferior larval instars of two ladybirds Menochilus sexmaculatus (Fabricius) and Propylea dissecta (Mulsant) (Coleoptera:Coccinellidae)

Abstract

Ladybird beetles are predatory insects, which consumes everal insect pests and have immense biocontrol potential, particularly against aphids. In prey scarcity, they resort to intraguild predation (IGP) by consuming immature stages of other heterospecific ladybirds. A laboratory experiment was performed to quantify the incidence of IGP of first and second larval instars by older instars and adults of two co-occurring ladybird species, Propylea dissecta and Menochilus sexmaculatus. IGP of first and second larval instars increased significantly with increase in the larval stages followed by adult males and females. Predatory stages of M. sexmaculatus were more potential intraguild predators than those of P. dissecta. Among adults, the female consumed a greater number ofearly and weaker heterospecific instars. The presence of dorsal spines and hair on the larva of  M. sexmaculatusprovided aposematism that helps in defense against superior heterospecific larvae thereby enabling its successful establishment and distribution. M. sexmaculatus could act as an intraguild predator in the fields and may contribute in declining the population density of P. dissecta during aphid-prey scarcity.