Interspecific host discrimination and intrinsic competition between Aphelinus asychis and Aphidius gifuensis in Myzus persicae

Abstract

AbstractAphelinus asychis Walker (Hymenoptera: Aphelinidae) and Aphidius gifuensis Ashmead (Hymenoptera: Braconidae: Aphidiinae) are solitary kionobiont endoparasitoids, which can parasitize the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). We determined the influence of oviposition sequence and various time intervals (0, 24, 48, and 72 h) between two ovipositions on self‐ and conspecific discrimination and interspecific intrinsic competition between A. asychis and A. gifuensis. When offered unparasitized M. persicae and those parasitized by the other parasitoid species, the two parasitoid species oviposited more often in unparasitized hosts. Aphelinus asychis and A. gifuensis could, however, not avoid to multiparasitize hosts parasitized by the other species. Both parasitoid species had a limited interspecific discrimination ability through ovipositor insertion to detect internal cues. Aphidius gifuensis most often out‐competed A. asychis. The outcome of this interspecific competition was not influenced by oviposition sequence or time intervals between two ovipositions. Aphidius gifuensis eliminated competitors by physical combat at the first instar and probably by physiological suppression in later stages; A. asychis possibly used physiological suppression in all larval stages.