Variation in the life history of the citrus mealybug parasitoid Leptomastix dactylopii (Hymenoptera: Encyrtidae) on three varieties of Coleus blumei.
Red-, yellow-variegated, and green-leafed plants of Coleus blumei were studied to determine host plant effects on the size of Planococcus citri and the life-history of its parasitoid Leptomastix dactylopii. Same-aged 4th-instar nymphs were significantly larger on red-variegated and green plants than on yellow-variegated plants. Body size of P. citri at parasitization was correlated positively with body size of emerging adult parasitoid females. Number of eggs within parasitoid adult females 24 h after adult emergence was correlated positively with parasitoid body size. Average fecundity of parasitoid females was significantly higher on red-variegated and green plants than on yellow-variegated plants. Survivorship of L. dactylopii was also higher on red-variegated and green plants. Overall, population growth rates (rm) of the parasitoid were higher on red-variegated and green-plants than on yellow-variegated plants. When differences among the population growth rates reported for P. citri on these plants are considered, the potential for biological control seems greatest on green plants. Thus, despite the positive relation between parasitoid rm and host size, L. dactylopii is unlikely to adequately compensate for plant-mediated increases in host population growth.