The foraging behaviour of Aphelinus asychis Walker (Hymenoptera: Aphelinidae) and Aphidius ervi (Haliday) (Hymenoptera: Braconidae) on Myzus persicae (Sulzer) (Hemiptera: Aphididae)

Host stage preference, immature survival, sex ratio and mutual interference of Aphelinus asychis and Aphidius ervi on Myzus persicae were investigated under laboratory (25 + 1 °C; 70 + 5% RH; 16 h light/8 h dark photoperiod). There was significant difference between the rates of parasitism by the two parasitoids on different stages of M. persicae. Second and third instar nymphs of M. persicae were the most preferred for parasitism by A. asychis and A. ervi, respectively. The maximum immature survival was highest (84.3% and 87.4%) in second and third instars of the aphid. A female biased sex-ratio was found for both the parasitoids. Nicholson’s model and linear regression were used to determine per capita search efficiency and the interference coefficient, respectively. The per capita parasitism and search efficiency of the parasitoids were observed to decrease with increase in parasitoid density. The study concluded that A. asychis and A. ervi are effective parasitoids of M. persicae and both of these can be mass reared and utilized in augmentative releases for the management of the aphid under greenhouse environments.