Diversity of coccinellidae in ecological compensation areas of Italy and overlap with maize pollen shedding period

Ladybird beetles (Coleoptera Coccinellidae) are important predators of aphids and other crop pests, and there is great interest in their conservation in agroecosystems. Bt-maize, genetically engineered to express insecticidal Cry proteins, is regarded as a taxon-specific way of controlling pests, but some concerns have been raised about the possibility of unintended negative effects on non-target organisms, including coccinellids. One of the possible routes of exposure of ladybird beetles to Cry toxins is by feeding on maize pollen, as for many species pollen is an important integrative food source. In this study, coccinellid adults were sampled by sweep netting in Ecological Compensation Areas (ECAs) in three sites of Northern and Central Italy, where conventional maize cultivars are grown (Bt-maize is currently forbidden for commercial cultivation in Italy). The coccinellid communities were sampled during and around the typical flowering periods of maize in order to check their diversity and their overlap with pollen shedding. A total of 11 species were recorded. Hippodamia variegata (Goeze), Coccinella septempunctata L. and the exotic Harmonia axyridis (Pallas) were the most abundant species in Northern Italy, whereas Tytthaspis sedecimpunctata (L.) and Coccinula quatuordecimpustulata (L.) were dominant in Central Italy. The potential exposure to maize pollen was different in the two areas, since in Northern Italy the maize flowering coincided with a period of high coccinellid activity in the field, whereas in Central Italy the ladybird population peaks occurred roughly one month earlier than the anthesis. The collected data might be useful for exposure characterization of ladybird beetles in a possible future scenario of Bt-maize cropping in the studied areas.