Interspecific host discrimination and intrinsic competition between A phelinus asychis and A phidius gifuensis in M yzus persicae

A phelinus asychis W alker ( H ymenoptera: A phelinidae) and A phidius gifuensis A shmead ( H ymenoptera: B raconidae: A phidiinae) are solitary kionobiont endoparasitoids, which can parasitize the green peach aphid, M yzus persicae ( S ulzer) ( H emiptera: A phididae). 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. A phidius 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.