Seasonal food of Ceratomegilla notata (Coleoptera: Coccinellidae) in mountain environments of Northern Italian Alps

The aim of this study was to clarify the diet of Ceratomegilla notata (Laicharting), a common species in different mountain habitats of the Palearctic region. In Italy it is found only in alpine ecosystems between 800–1700 m. In these areas, up to 1200 m, various crops (e.g., maize, potatoes) are present. The high meadows are cut for hay. From 2002 to 2003 investigations on the foraging behaviour of this ladybird were carried out in mountain habitats (six near Villabassa, in Bolzano province, and six near Soraga, in Trento province) and in the “Paradisia” Botanic Garden (Gran Paradiso National Park). C. notata adults and larvae were found on the flowering plants, especially those infested by aphids. The study of their diet was done taking random D-Vac samples of 20 adults and 20 larvae/habitat every 15 days, between July and September. The influence of the haymaking on C. notata populations was also evaluated. In agricultural fields the ladybirds prey on Rhopalosiphum maidis (Fitch), R. padi (L.) on maize and on Acyrthosiphon pisum (Harris) and Therioaphis luteola (Born.) on Trifolium pratense L. In the natural pastures, adults and larvae feed on Cavariella theobaldi G. & B. found on Heracleum sphondylium (Umbelliferae), Sitobion avenae L. on Avena sativa L., Megoura viciae (B.) and A. pisum on Vicia cracca L., Uroleucon jaceae (L.) on Cirsium arvense Scop., U. cichorii (Koch) on Hypochaeris radicata L. and Macrosiphum weberi Born. on Scabiosa sp. A study of the gut contents revealed the presence of aphids, Umbelliferae pollens and spores of fungi (e.g., Alternaria spp., Helminthosporium spp., Puccinia spp.). Statistically significant associations between different food sources were more frequent for adults than for larvae in both 2002 and 2003. Thrips are an important prey of this ladybird in the absence of aphids. C. notata is an important aphidophagous species in Alpine habitats.