Species composition and abundance of natural enemies of Myzus Persicae (Sulzer) in potato agro-ecosystem in Shimla hills

Aphids M. persicae (Sulzer) are one of the most serious pests of potato crop world wide, causing major yield and economic losses. Despite advances in integrated pest management, and frequent use of insecticides, the industry is still plagued by the insect. Adding to the problem is the fact that the peach aphid has proved to be resistant to various insecticides so there is a need to shift emphasis on biological control agents. Natural enemies could be a good option therefore, the present studies were carried out to observe the occurrence and diversity of natural enemies of green peach aphid, M. persicae in Shimla hills in potato and surrounding vegetation and the effect of weather parameters on their seasonal abundance. The periodical sampling of natural enemies (predators and parasitoids) associated with green peach aphid revealed the occurrence of four species of hoverflies (Hymenoptera) viz. Episyrphus balteatus, Eupeodes sp., Scaeva pyrastri, four species of coccinellids (Coleoptera) viz. Coccinella septempunctata, Menochilus sexmaculata, Adalia quadrispinolata, Adalia decempunctata, a neuropteran Chrysoperla carnea and two species of parasitoids (Hymenoptera) viz, Aphelinus abdominalis and Aphidius sp. Seasonal abundance of predators synchronized with the pest activity, maximum being during July to August. The mummification rate showed a specific increasing trend late in the season (August – September). Correlation between the natural enemy and abiotic factors revealed a positive effect on their population dynamics (except for relative humidity w.r.t parasitoids showing negative non-significant correlation). Among the predators C. septempunctata and M. sexmaculata were most abundant therefore their feeding potential was evaluated under controlled conditions which revealed that different larval stages of C. septempunctata and M. sexmaculata fed an average of 372.1±6.25and 316.71±8.60 aphids during the complete larval period, whereas the feeding potential of adults were 66.3± 15.2 and 57.0± 10.0 aphids per day, respectively.