Coccinellids are important predators of aphids in many agroecosystems, however intraspecies competition over shared prey or consumption of alternative herbivore or intraguild prey may limit efficacy as biological control agents. Historically, efforts to understand coccinellid contributions to biological control have focused on detecting aphid species of economic importance, however DNA sequencing advances now allow for detection of a broader spectrum of prey. This study utilizes both taxonomically broad metabarcoding and narrow melting curve analysis to characterize the adult diets of three coccinellid species (Coleomegilla maculata, Harmonia axyridis, and Hippodamia convergens) in a Brassica agroecosystem. Analyzing how these species consume different prey types (herbivore, intraguild, resident, non-resident) and the influence of diet breadth on consumption of prey types varies among coccinellid species reveals distinct trophic ecologies for cooccurring predator species. Our molecular methods detected a variety of prey types within the coccinellids sampled predators. Both resident and nonresident herbivore species were detected, indicating that a subset of coccinellids had recently moved into the Brassica agroecosystem habitat. Consumption of intraguild coccinellid prey was detected in all predator species, as well as a single detection of aphid parasitoid Aphidius ervi. Variation in prey detected among predator species indicates that distinct diets can exist within a single predatory family, which may enhance their ability to provide strong herbivore population control.
