ChileanJAR

In order to reduce the general equilibrium position of M. dirhodum and S. avenae, three species of parasi toids of cereal aphids were introduced in sóuthern Chile, during 1977 and 1978. The parasitoids Aphidius ervi (Haliday), Aphídíus rhopalosiphi-uzbekistanicus, and Monoctonus nervosus (Haliday) were reared in greenhouses, and subse quently were released in different localities of the Malleco and Cautín provinces. During the spring foliowing their introduction, the es tabtist1ement of the parasitoids A. ervi and A. rhopaIosiphi-uzbekistanícus was determ ined i n both aphids. During the 1978/1979 and 1979/1980 sea sqns, the maximum percentage of parasitism (mum myfied aphids), determined on the total aphid popu lation in spring wheat, was 14.7 and 11.8%, respecti vely. These results. suggest that the introduced parasi toids may become mportant regulators of the aphld population in southern Chile.