Effect of size, extraguild prey and habitat complexity on intraguild interactions: a case study with the invasive ladybird Harmonia axyridis and the hoverfly Episyrphus balteatus

摘要: Intraguild predation (IGP) is a widespread interaction between predatory arthropods, and influenced by several factors. The harlequin ladybird, Harmonia axyridis (Coleoptera: Coccinellidae), has frequently been reported as an intraguild predator of other Coccinellidae, but little known about its interactions with aphidophagous predators, including syrphids. This study investigated the incidence IGP H. Episyrphus balteatus (Diptera: Syrphidae), most abundant hoverfly species in Europe commercially available aphid biocontrol agent. influence size, presence extraguild prey habitat complexity were through laboratory experiments Petri dishes on potted broad bean plants. In both types arenas, E. was found to be asymmetric, coccinellid majority cases being predator. There significant effect size frequency IGP. efficiency increased developmental stage. Early instars vulnerable Pupae either not attacked. prey, substantially reduced. However, still occurred, mainly combinations older larvae first or second balteatus. arena affected balteatus, third instars. Field research needed elucidate ecological relevance among these predators.