بررسي تغييرات جمعيت شكارگرهاي شته هاي سورگوم جارويي در منطقه ميانه

Population fluctuations of broom corn aphid specific predators in Miyaneh region, Iran

Aphids are the most important pests of broom corn, Sorghum cernuum, in Miyaneh region and chemical pesticides are severally used for plant protection by farmers regardless to beneficial insectʹs activity. With respect to the importance of conservation strategy of natural enemies in integrated pest management programs, aphid specific predators including lady beetles, flower flies and lacewings were collected and identified and their population fluctuation were compared to that of host aphids. Collection of predators was done by sweep net and visiting aphid colonies. The flower fly Sphaerophoria scripta , lacewing Chrysoperla carnea, and five species of lady beetles including: Coccinella septempunctata, C. undecimpunctata, ,Hippodamia variegata, Scymnus cf. frontalis and Propylea quatuordecimpunctat were collected from greenbug, Schizaphis graminum and maize leaf aphid, Rhopalosiphum maidis colonies. Synchronization and positive correlation of greenbug and flower fly populations was observed due to host specificity of Sphaerophoria scripta . Among lady beetles, Scymnus cf. frontalis was the most frequent and important species due to oviposition on broom corn and itʹs population showed positive significant correlation with that of maize leaf aphid. However adult lacewing Chrysoperla carnea is a carbohydrate feeder and did not lay any egg on the field, and so it had not any role in controling aphid populations of broom corn.