Intraguild predation within an aphidophagous community: interactions between Chrysopidae and Coccinellidae and their potential for biological control

Green lacewings (Chrysopidae:Neuroptera) and ladybeetles (Coccinellidae:Coleoptera) are recognized as aphid predators, and promoting these natural enemies reduce the need for pesticides. However, these predators consume similar resources and with overlapping distributions, intraguild predation (IGP) may disrupt biological control. In this study, we examined the biological control capabilities of lacewings and ladybeetles and frequency of intraguild predation of in a winter wheat agroecosystem. The primary aphid pests of winter wheat are Sitobion avenae and Rhopalosiphum padi, which cause considerable yield loss as vectors of Barley Yellow Dwarf virus (BYDV), prompting the routine use of insecticides in Kentucky. Understanding the interactions of aphidophagous predators is crucial to developing the ecological framework for sound pest management decisions. 

 We collected predator and prey abundance data by sweep net sampling in winter wheat fields over 2 growing seasons. Using PCR-based gut content analysis and species specific primers, we screened lacewing specimens collected from the field for intraguild predation on ladybeetle species Coleomegilla maculata and Coccinella septempunctata and predation of aphid species S. avenae and R. padi. Field results indicate that lacewing and ladybeetle populations peak at the same time and concentrate in areas with high aphid frequencies, making this a model system for IGP and conservation biological control studies. Our results suggest that lacewings contribute to biological control of aphids, and larval IGP of coccinellids is infrequent and does not disrupt biological control.