Coccinellids in diverse communities: Which niche fits?

Predaceous lady beetles (Coleoptera: Coccinellidae) are a well-studied group of consumers that can yield insight into relationships among interspecific niche differences, species richness, and prey consumption. In various studies, sympatric lady beetles differ in habitat-use at the scales of landscapes, single agricultural fields, and single plants. Species also differ in their seasonal and diel activity-patterns. These spatiotemporal differences in habitat-use should lead to complementary impacts on prey, by encouraging different predator species to attack different subsets of the prey population. This in turn should lead to stronger biological control at higher predator diversity levels. Indeed, experimental manipulations of predator species richness in communities that include coccinellids have generally revealed stronger prey suppression with greater predator biodiversity. In these experimental studies, lady beetles sometimes filled unique niches as particularly voracious predators, and often also complemented or facilitated prey capture by other species. Intraguild predation was rarely found to be a strongly disruptive force, perhaps because spatiotemporal niche differences reduced encounters among species. In summary, coccinellid species both respond to and affect their communities in unique ways, generally to the benefit of herbivore suppression. Thus, the best niche fit for coccinellids may be that of a complement to other species, contributing to improved biological control with greater predator biodiversity.