Occurrence of aphid predator species in both organic and conventional corn and broad bean

Organic farming has been suggested to enhance beneficial species abundance and diversity in agrosystem habitats. In this study, the abundance of aphid predators was compared in organic and conventional corn and broad bean fields during a two-year inventory. In both farming strategies, there were no differences between species diversity. Five aphid predator species were mainly observed: Coccinella septempunctata L. 1758 (Coleoptera: Coccinellidae), Propylea quatuordecimpunctata (L. 1758) (Coleoptera: Coccinellidae), Harmonia axyridis Pallas 1773 (Coleoptera: Coccinellidae), Chrysoperla carnea (Stephens 1836) (Neuroptera: Chrysopidae) and Episyrphus balteatus (De Geer 1776) (Diptera: Syrphidae). Differences in abundance of aphidophagous species between conventional and organic crop fields were observed even if not always in favour of the latter condition. The abundance of the five above- mentioned aphidophagous species varied for the most part according to almost all the observed parameters, including sampled year, crop and agricultural practices. In conclusion, our findings do not support organic practices in corn and broad bean as key options to increase the biodiversity and abundance of aphid natural enemies.