A SURVEY OF PARASITOIDS OF BROWN CITRUS APHID (HOMOPTERA, APHIDIDAE) IN PUERTO-RICO

The brown citrus aphid Toxoptera citricida (Kirkaldy) (Homoptera: Aphi didae) is a pest of citrus and an efficient vector of citrus tristeza virus. Reproducing populations of this aphid were first detected in Pu erto Rico in April 1992. In 1994, we surveyed citrus in Puerto Rico fo r the aphid and its parasitoids. The brown citrus aphid was the most a bundant aphid on citrus and its populations were statistically higher in April than in July and December. Aphid populations in commercial an d dooryard citrus were significantly higher than those in nurseries (P < 0.05). Lysiphlebus testaceipes (Cresson) (Hymenoptera: Aphidiidae) was the only primary parasitoid found attacking the aphid. The parasit ism rate was only 3.6% overall and was somewhat greater in April at 5. 9% and December at 7.0% than in July at 2.9%. Parasitism was higher in dooryard citrus than in commercial or nursery fields (P < 0.05). Prim ary parasitoid emergence rate from mummies was low at 4.0%, indicating that the brown citrus aphid was a marginal host or that conditions we re not adequate. A low level of hyperparasitism by Pachyneuron sp. was also observed. We conclude that the aphid was not under good biologic al control by parasitoids and suggest that classical biological contro l efforts should be undertaken. (C) 1996 Academic Press, Inc.