Quantifying the roles of competition and niche separation in native and exotic coccinellids, and the changes in the community in response to an exotic prey species

Coccinellids are of enormous importance in natural and agricultural systems. Their use as biological control agents has moved different species around the globe. In Michigan two exotic coccinellids are present in the community and their interactions with each other and the native community was examined to provide a more detailed picture of community niche separation. Twelve years of data was used to examine the temporal and spatial dynamics of the exotic species. The dominant members of the community were then analyzed to elucidate the mechanics of niche separation via temporal, spatial, and habitat characteristics using spatial and statistical analysis techniques. The third exotic in the landscape is the recently arrived soybean aphid; the response of the dominant members of the community to this new food resource was examined for possible perturbations in the interactions within the coccinellid community. The exotic species were found not to be in direct competition due to a temporal separation in their niches. The four dominant coccinellids segregated themselves by microhabitat and displayed responses to the soybean aphid ranging from none, to a very strong numerical and spatial response.