Lady beetles (Coleoptera: Coccinellidae) of Minnesota soybean and small grains fields

Lady beetles (Coleoptera: Coccinellidae: Coccinellini) offer important ecological services by preying upon agricultural pests. However, in recent years, concerns have arisen about the impact of the invasion of non-native lady beetle species and climate change on the community structure of these predators and the biological control services they offer. To inventory the lady beetle community in Minnesota agricultural fields, soybean and small grains from throughout the state were sampled by sweep net in 2011 and 2012. Prevalence (i.e., proportion of fields with a given species), abundance (i.e., number of individuals of each species) and diversity (i.e., number of species) were estimated and compared between years and crops. Preliminary analyses indicate that Hippodamia convergens and Coleomegilla maculata were the most prevalent species in small grains, whereas Harmonia axyridis, Hippodamia tredecimpunctata, and Hippodamia variegata were the most prevalent species in soybeans. The most abundant species were H. convergens and C. maculata in small grains while H. axyrdis and H. convergens were most abundant in soybean.  Diversity of species will also be discussed.  This survey documented the widespread distribution of a recent invader, H. variegata. In addition, the previously common, but currently rare Coccinella novemnotata was found in soybean in east central Minnesota. This study provides baseline data for examining future impacts of non-native species and climate change on the lady beetle community in agricultural fields.  Furthermore, this inventory can aid in determining lady beetle species that may be of interest in future assessments of biological control services offered in Minnesota crop fields.