The relationships between predatory Heteroptera and their potential prey species were investigated during two crop seasons in an inter-mountain area close to the Pyrenees (Iberian Peninsula). Regression was used to analyze the potential numerical responses shown by heteropterans to aphids and other potential prey during alfalfa intercuts (the plant growth period between cuts) of high aphid occurrence. The most abundant heteropterans were Orius spp., Nabis spp. and mirids, and all were present in alfalfa stands throughout the season. Acyrthosiphon pisum was the prevalent species during the 2nd intercut, Therioaphis trifolii during the 4th and Aphis craccivora during the 5th. We performed simple regression analysis between the Orius sp., Nabis sp. and mirids and the prevalent aphid species, forward multiple regression analysis between heteropterans and all possible soft-bodied prey species; and both analyses for coccinellids, as relative aphid predator specialists. The heteropterans responded numerically to A. pisum but not to T. trifolii or A. craccivora. Heteropterans also showed numerical responses to other potential prey (leafhoppers, thrips, and other soft bodied prey) that remained at low densities throughout the season. All these preys may contribute to the presence of heteropterans in alfalfa stands throughout the season. The results suggest that heteropterans may contribute to reduce A. pisum, particularly at the beginning of the growing season, and on other potential pests when they invade or recolonize alfalfa, and may help to delay or prevent the build-up of these pest populations.
Qualitative and quantitative differences in prey are known to affect the life histories of predators. A laboratory study was used to evaluate the suitability of three aphid prey, Aphis gossypii, Aphis craccivora and Lipaphis erysimi, for the ladybird beetle, Anegleis cardoni (Weise). Development was fastest on A. gossypii followed by A. craccivora and L. erysimi. Percentage pupation, immature survival, adult weight and the growth index were all highest when reared on A. gossypii and lowest on L. erysimi. Similarly, oviposition period, lifetime fecundity and egg viability were all highest on a diet of A. gossypii, lowest on L. erysimi and intermediate on A. craccivora. Age-specific fecundity functions were parabolic. Adult longevity, reproductive rate and intrinsic rate of increase were all highest on A. gossypii and lowest on L. erysimi. Life table parameters reflected the good performance on A. gossypii and poor performance on L. erysimi. Estimates of individual fitness values for the adults reared on A. gossypii and A. craccivora were similar and higher than that of adults reared on L. erysimi. Thus, the three species of aphid can all be considered essential prey for A. cardoni.
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., Snehasish Routray, Karnam V. Hari Prasad., and Obsahuje bibliografii