Spider predation on rosy apple aphid in conventional, organic and insecticide-free orchards and its impact on aphid populations

Publication date: Available online 29 October 2016 Source:Biological Control Author(s): Manon Lefebvre, Pierre Franck, Jérôme Olivares, Jean-Michel Ricard, Jean-François Mandrin, Claire Lavigne Spiders dwelling in the canopy of apple trees may contribute to the control of the rosy apple aphid (Dysaphis plantaginea) in spring. They are expected to be very efficient early in the season during aphid colony establishment. However, their predation on aphids may be impaired by insecticide treatments. In the present study, we aimed to assess the effectiveness of spider predation on D. plantaginea in apple orchards. For this purpose, we sampled a total of 1281 canopy spiders in 8 orchards under IPM (Integrated Pest Management), organic or insecticide-free management in the early and mid-season. DNA analyses of the spider guts with specific D. plantaginea PCR primers were performed to estimate which taxa had eaten this aphid pest in the early and mid-season. Lastly, we assessed the effectiveness of aphid suppression by spiders in insecticide-free orchards during these two periods. The most abundant spiders collected belonged to the Philodromidae, Salticidae and Anyphaenidae families. Spiders were more abundant in the insecticide-free orchards than in the other orchards in the mid-season but not in the early season. The positive detection of D. plantaginea DNA was observed in 8 out of the 12 most abundant families and occurred in all orchards. The probability for a spider to...

Source: Biological Control - October 28, 2016 Category: Biology Source Type: research