LAUSR

Larvae of aphidophagous ladybirds attack vulnerable stages, such as eggs of conspecific and heterospecific species during prey scarcity, especially when the aphid colony is declining. We investigated food-preference of all four larval instars of ladybirds, viz. Propylea dissecta (Mulsant) , Menochilus sexmaculatus (Fabricius) and Coccinella septempunctata Linnaeus, towards various egg-diets and the influence of different monotypic egg-diets on the consumption rate, growth-rate, conversion efficiency, mortality, bodyweight and development. All larval instars of P. dissecta and M. sexmaculatus preferred egg-cannibalism over IGP, while lower instars of C. septempunctata showed no preference and its higher instars preferred vice-versa. The three species developed successfully on monotypic conspecific and heterospecific egg-diets. However, instars developed faster into heavier life stages with lesser mortality when fed on conspecific eggs. The fourth instars of the three-ladybird species had higher consumption rates and conversion efficiencies, while the first instars had higher growth rates than other instars. These parameters were optimal when instars fed on aphids, while conspecific eggs were better diets than heterospecific eggs. The consumption rates of C. septempunctata were higher than the other two ladybird species, however it lagged behind the two in terms of growth rates and conversion efficiencies. The overall mortality was lowest when instars of three ladybirds were fed on aphids followed by conspecific eggs and heterospecific eggs. We also conclude that C. septempunctata eggs may be less palatable to both conspecifics and heterospecific predators and latter ensure survival by refraining intraguild predation and not risking their fitness.