Preference of the aphidophagous ladybird Propylea dissecta for two species of aphids reared on toxic host plants

We investigated prey preference of adult male and female Propylea dissecta (Mulsant) when fed on the aphids, Aphis craccivora and Lipaphis erysimi, which sequester toxic allelochemicals from their host plants. Both the male and female adults of P. dissecta prefer to consume L. erysimi in most mixed diet treatments (cafeteria experiment). This was well supported by significantly high values of the β and C prey preference indices. However, when provided with these aphids separately, the adults showed no significant difference in aphid consumption, regardless of the species of aphid and sex of the adult ladybird. We conclude that host plant allelochemicals/toxicants have a direct effect on prey preference of ladybirds. Host plant toxic constituents can alter the biochemical composition of the most preferred prey and make them the least preferred. Mixing two toxic similar diets can make one diet more suitable than the other.