Study On Interspecific Competition By Parasitoids Of Bactrocera Dorsalis (Hendel)

Bactrocera dorsalis (Hendel) is one of the most important quarantine pests in the world. The interspecific interaction of the egg parasitoid Fopius arisanus (Sonan) and the larval parasitoids Psyttalia incise (Silvestri), Fopius vandenboschi (Fullaway) and Diachasmimorpha longicaudata (Shmead) were studied under laboratory condition. In order to offer valuable consult for releasing in controlling B. dorsalis.Interspecific competition between F. arisanus and P. incise, the P. incise can not discriminate the hosts which had previously been parasitized at egg stage by F. arisanus. Most of the host died which parasitized by F. arisanus at egg stage first and parasitized by P. incise second, and the emerged adults from the host pupal were mostly F. arisanus. Total percentage emergence of parasitoids were both higher in hosts previously exposed to F. arisanus then exposed to P. incise than in those exposed to only one species.Interspecific competition between F. arisanus and D. longicaudata, the D. longicaudata can not discriminate the hosts which had previously been parasitized at egg stage by F. arisanus. Most of the host died which parasitized by F. arisanus at egg stage first and parasitized by D. longicaudata second, and the emerged adults from the host pupal were mostly F. arisanus. Total percentage emergence of parasitoids were both higher in hosts previously exposed to F. arisanus then exposed to D. longicaudata than in those exposed to only one species.Interspecific competition between F. arisanus and F. vandenboschi, the F vandenboschi can not discriminate the hosts which had previously been parasitized at egg stage by F. arisanus.Interspecific competition between P. incise and D. longicaudata, when B. dorsalis larvae were exposed to both parasitoids concurrently, the total parasite ratio to3-day-old hosts was88.40%, and the total percentage emergence of parasitoids from4-day-old hosts was82.00%. The D. longicaudata can discriminate the hosts which had previously been parasitized by P. incise, but the P. incise can not discriminate the hosts which had previously been parasitized by D. longicaudata. The percentage emergence of P. incise was higher than D. longicaudata in hosts previously exposed to P. incise then exposed to D. longicaudata, and total percentage emergence of parasitoids was higher than in those exposed to only one species.The percentage emergence of D. longicaudata was higher than P. incise in hosts previously exposed to D. longicaudata then exposed to P. incise, and total percentage emergence of parasitoids was lower than in those exposed to only one species. When host larvae were parasitized first by P. incise, then exposed to D. longicaudata after48h, the emeraged parasitoid adult were only P. incise.