Intraguild Predation between Aphidophagous Lady Beetles: Chemical Perspectives on Community Effects

Intraguild predation (IGP: predators sharing a common prey eating each other) potentially limits the effectiveness of multiple predator biocontrol agents, especially within aphid eating insects. Many field and laboratory experiments suggest that IGP between predatory aphid-eating Coccinellidae (lady beetles) is widespread; however their results are at variance with those concentrated on the chemistry of coccinellid IGP, which suggest that predation of other species is often costly, frequently resulting in the consumption of potentially toxic species-specific alkaloids from the prey. Using a community of five coccinellids occurring in Kentucky agroecosystems, this work aims to determine the chemical basis of this variability in coccinellid IGP in the laboratory, through acceptability and toxicity experiments and to test resulting hypotheses in the field community. We will use gas chromatography-mass spectroscopy (GCMS) of prey alkaloids to examine the ir fate in intraguild predators and to provide a tool for the detection of predation of coccinellids occurring in the field. Thus we also aim to validate a rew and valuable tool for other predator-prey systems where molecular biological tools are too difficult, costly or time consuming to develop. By increasing our knowledge of the functioning of aphidophagous coccinellid communities, and consequent management, thus reducing pesticide usage, this project will both enhance economic opportunities for agricultural providers (CSREES goal 1) and protection of the nation's food supply (goal 3); the focus on interactions between introduced and native coccinellids will also facilitate the conservation of biodiversity in agricultural ecosystems, an important resource base for the future (goal 5).