A Survey on Species Composition of Parasitoids against Aphis gossypii in Zanthoxylum schinifolium at Different Altitudes

The species composition and number of the parasitoids against Aphis gossypii in Zanthoxylum armatum were investigated at different altitudes of 800-1800 meters in Jin Yang county. The parasite rate of parasitoids was 2.63%. Four species of parasitic wasps belonging to 3 families, 3 genera were found: Aphidencyrtus aphidivorus, Trioxys indicus, T. sp., Aphelinus gossypii. Trioxys indicus account for 90.38% of the total number of parasitic wasps, and was the dominant population of Aphis gossypii. The other three species were Aphidencyrtus aphidivorus , T. sp. and Aphelinus gossypii. According to statistics, the ratio of Female-Male of Trioxys indicus decreased with the increase of altitude in the range of 1000-1800 meters.