The brown citrus aphid, Toxoptera citricida (Kirkaldy), is an exotic pest of citrus in the United States that was introduced into Florida in 1995. The native parasitoid Lysiphlebus testaceipes (Cresson) has demonstrated acceptance of the brown citrus aphid as a host. This experiment evaluated the effect of citrus host plants on brown citrus aphid parasitism by L, testaceipes, and the effect of temperature on development of the parasitoid. The levels of parasitism achieved by L. testaceipes were similar among brown citrus aphid populations on five citrus cultivars used as host plants for the aphids (range 34-36%). The percentage of adult parasitoid emergence was highest on 'Duncan grapefruit' (82%) and significantly lower on 'Mexican lime' (63%) than on any of the other citrus cultivars. The proportion of adults that were female was significantly higher on 'Duncan grapefruit' (81%) than on any of the other cultivars. The results demonstrate that the effects of multiple trophic levels can influence parasitoid performance in a cascading manner. The developmental periods for both male and female L. testaceipes on the brown citrus aphid declined from 21 to 9 d with ascending temperatures in the range 18-27[degree]C. The developmental threshold was 10.4[degree]C and the degree-day (DD) requirement for development was 158.7 DD, indicating that the temperature conditions experienced in Florida are conducive to rapid development of L. testaceipes on the brown citrus aphid. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Abiotic factors; Physical factors; Land zones; Nearctic region; USA; North America Lysiphlebus testaceipes (Aphidiidae); Hemipteran hosts; Toxoptera citricida; Parasite prevalence; Temperature; Florida; Parasite prevalence on hemipteran hosts, effect of temperature & host plant host choice Toxoptera citricida (Aphidoidea); Hymenopteran parasites; Lysiphlebus testaceipes; Parasite prevalence; Plant hosts; Citrus plants; Temperature; Florida; Hymenopteran parasite prevalence, effect of temperature & plant host choice none