Prey Range and Voracity of Main Insect Natural Enemies of Pests in Corsican Clementine Orchards

ABSTRACT Clementine trees are the target of numerous pests and pathogens. To face these attacks, pesticides are intensively used by farmers, degrading orchard ecosystems and biodiversity. To offer alternative solutions from pesticides, such as biocontrol, a better understanding of the natural regulation provided by natural enemies is required. Our study aimed to assess the biocontrol potential against the main arthropod pests of clementine orchards in Corsica based on the local composition and abundance of natural enemy communities, by taking into accounting the prey range and voracity of the most abundant predators. First, laboratory experiments were carried out using four specialist predators, the coccinellid species Coccinella septempunctata (L.), Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) and Cryptolaemus montrouzieri (Mulsant) (Coleoptera: Coccinellidae) and one generalist predator, the European earwig, Forficula auricularia (L.) (Dermaptera: Forficulidae). Their prey range and voracity were tested on 3 prey types: an aphid, Aphis fabae (Scopoli) (Hemiptera: Aphididae), a mealybug Pseudoccocus/Planococcus sp. (Hemiptera: Pseudococcidae), and a whitefly Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). Then, in a set of monitored orchards, a global predation index at the scale of the entire community of insect predators on each prey was assessed by weighting the composition and abundance of the community by the voracity of each natural enemy species. Finally, this predation index was used to compare the biological control potential in organic and conventional orchards. The index highlighted no major effect of the type of management of the orchards on the biological control of pests. Only the contributor were different, and their abundances varied between orchard. The main aphid regulators were C. septempunctata , coccinellid larvae, and F. auricularia . For mealybugs, they were C. montrouzieri and F. auricularia , and for whiteflies, they were C. septempunctata and F. auricularia .