Preference–performance of a generalist predatory ladybird: A laboratory study

Abstract

The fitness consequences of feeding on different aphids, viz. Aphis craccivora, Aphis gossypii, Aphis nerii, Lipaphis erysimi, Myzus persicae, Rhopalosiphum maidis, and Uroleucon compositae (Homoptera: Aphididae), for the life stages of a generalist predatory ladybird, Propylea dissecta (Coleoptera: Coccinellidae) were measured in the laboratory in terms of their preference (prey biomass consumed and oviposition site selection), performance (development, survival, reproduction, mortality and fertility life tables, and individual fitness levels of predator), and preference–performance correlations. The study revealed that P. dissecta consumed A. craccivora the most and deposited more eggs on plants infested with this aphid species. The performance levels of predator varied significantly between aphid species with best performance on A. craccivora and worst on A. nerii. High performance on A. craccivora was contradictory to most literature and can be attributed to host plant dependent prey suitability. P. dissecta seems to be a generalist aphidophagous ladybird as it readily developed and reproduced on all seven aphid species. We correlated a composite performance measure (individual fitness) to two estimates of preference (biomass of prey consumed and oviposition site selection). Positive preference–performance correlations suggest that preferential prey consumption and selection of a host plant–prey complex as an oviposition site are an indicator of ladybird performance.