Seasonal abundance of the brown citrus aphid Toxoptera citricida, (Homoptera: Aphididae) and its natural enemies in Puerto Rico

Populations of the brown citrus aphid (BCA), Toxoptera citricida (Kirkaldy), and associated insects were monitored in citrus groves in western Puerto Rico in 1996 and 1997. Peak populations of the aphid were observed in spring and fall of both years. A total of 6,737 infested citrus terminals were examined and categorized by growth stage and BCA colony size. Natural enemies, primarily coccinellids, syrphids, chrysopids, and aphidiids, were recorded when present in BCA colonies and a list of species is presented. A complex of large coccinellid species was inferred to have the greatest potential for impact on BCA populations in Puerto Rico. Predation by syrphid larvae was another important source of BCA mortality. The parasitoid, Lysiphlebus testaceipes (Cresson), was abundant in some samples, but usually parasitized only a small percentage of aphids within colonies. The fungus, Verticillium lecanii (Zimm.), infected BCA colonies sporadically. The red imported fire ant, Solenopsis invicta Buren, was often observed harvesting honeydew from BCA colonies and interfering with natural enemies.