Ladybird, Menochilus Sexmaculatus (Fabricius) Can Survive o Oophagy but with Altered Fitness than Aphidophagy

Egg consumption is common among insects, including ladybirds. The consumed eggs may be conspecific or heterospecific. Egg consumption eliminates potential competitors and provides additional nutrients for development and reproduction. In ladybirds, the incidence of cannibalism and intraguild predation has been proven as alternative tactics for the sustenance of life under prey-scarce condition. The consumption of conspecific eggs is known as cannibalism. Thus, in this study we have evaluated the effect of diets, viz. conspecific and heterospecific eggs along with aphids on egg consumption, developmental and reproductive attributes of a ladybird beetle, Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae). We found that all the immature stages and adults prefer and consumed more conspecific eggs than heterospecific eggs possibly owing to low toxicity. Fourth instars and adult females consumed higher number of conspecific (82.15 ±4.94 and 85.04 ±0.05 respectively) and heterospecific eggs (56.61 ±0.44 and 60 ±0.48 respectively) than other life stages. Further the life stages developed faster on aphids followed by conspecific and heterospecific eggs. Besides aphids, overall maximum number of eggs was laid on conspecific eggs (84.00 ±1.92) followed by heterospecific eggs (67.70 ± 1.07). However, reverse trend was observed for per cent egg viability. Thus, with scarcity of primary prey (aphid), ladybirds consume and reproduce on conspecific/heterospecific eggs as alternative diets.