Host plant-mediated prey preference and consumption by an aphidophagous ladybird, Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae)

Abstract

Abstract The impact of host plant-aphid combination on the prey consumption and prey preference by adult ladybird, Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae) was studied, using aphid-prey, Aphis craccivora (Koch) and Lipaphis erysimi (Kalt.), in the laboratory. Monotypic aphids, A. craccivora, raised separately on Indian bean, Dolichos lablab L., and poison buttercup, Ranunculus sceleratus L., and L. erysimi cultured on radish, Raphanus sativus L., and mustard, Brassica campestris L., were provided. Adult male and female ladybirds consumed significantly greater number of A. craccivora infested on D. lablab than those on R. sceleratus. Similarly, they consumed a greater number of L. erysimi raised on R. sativus than those on B. campestris. The results indicated that host plant allelochemicals/toxicants had a direct effect on the palatability and prey consumption, as the ladybird treated the same aphids differently that was raised on different hosts. Prey preference, using a choice condition, was tested by providing both the aphid species raised on toxic hosts in a common microcosm. Both adult male and female of M. sexmaculatus preferably consumed the aphid, A. craccivora-infested R. sceleratus over L. erysimi-infested B. campestris in all diet treatments. The preference indices (β and C) further skewed the results towards A. craccivora, which suggest that ladybirds preferred A. craccivora on encountering aphids raised on toxic hosts. It could be concluded that dietary selection in ladybirds depends largely on the aphid–host combination, and a suitable host may aid the augmentative rearing of both aphids and ladybirds.

Keywords

• Aphids
• Aphis craccivora
• Brassica
• Menochilus sexmaculatus
• Diet
• Lipaphis erysimi