Tri-trophic interaction involving host plants, black legume aphid, Aphis craccivora (Hemiptera: Aphididae) and the predator, Cheilomenes sexmaculata (Coleoptera: Coccinellidae)

Abstract

Interactions involving host plants (cowpea, groundnut, cotton, sunflower, greengram, blackgram) an insect herbivore, black legume aphid Aphis craccivora Koch (Hemiptera: Aphididae) and a predator, the zigzag beetle Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) were investigated during 2014-2015. The preference of the aphid A. craccivora for host plants measured in terms of growth and multiplication was cowpea > groundnut > greengram > blackgram > sunflower > cotton (most preferred to least preferred). Cowpea was the most preferred host plant for growth and multiplication of A. craccivora. Aphid's oviposition period was longest, fecundity greatest; adult longevity longest (188.40 ± 28.87 h; 52.00 ± 10.92; 231.60 ± 40.41 h), and nymphal mortality was lowest (0%) when reared on cowpea followed by groundnut, greengram and blackgram. Aphids had highest nymphal mortality (100%), with very few or no live adults produced, when reared on sunflower and cotton, the least preferred host of A. craccivora in this study. At the third trophic level, both the larvae and the adults of the coccinellid, Cheilomenes sexmaculata, consumed more of the aphids reared on groundnut than of those reared on blackgram, greengram, cowpea, sunflower and cotton. The biochemical constituents (phenols) present in cotton and sunflower, which contributed to the aphid's nymphal mortality, also affected the feeding behaviour of the coccinellid.