Quantifying intraguild predation among native and non-native lady beetles (Coccinellidae) across the Midwestern US

Biodiversity is important in order to maintain high functioning ecosystems, but species loss is occurring globally at a rapid pace almost on par with a mass extinction. Understanding the mechanisms behind species decline is imperative to protect the future of our ecosystem services. Non-native invaders are the second leading treat to biodiversity. In the case of native lady beetle (Coccinellidae) decline, non-native lady beetles are often cited as the primary culprit. The establishment of a series of non-native lady beetle species coincided with the decline of several native lady beetle species across the US. A common hypothesis is that direct competition via predation by non-natives is the primary mechanism by which non-native lady beetles have influenced native lady beetle decline. Previous studies, for the most part have focused on only two to four lady beetle species within a single location. This study examines four native and four non-native lady beetle species across thirteen states in Midwestern US and quantifies the incidents of intraguild predation among all eight species. Collections were conducted in alfalfa fields and a total of 2,500 beetles were collected. A minimum of 30 individuals per species at each location were needed before that sample was included for statistical analyses. Species specific primers were designed and PCR was preformed to examine gut contents of all lady beetles. Results of this study elucidate the amount of intraguild predation among Midwestern lady beetles and offers a more comprehensive examination of the effect of intraguild predation on native lady beetles.