common name: a citrus blackfly parasitoid
scientific name: Encarsia opulenta (Silvestri) (Insecta: Hymenoptera: Aphelinidae)

Introduction - Distribution - Description - Biology - Hosts - Selected References

Introduction

Encarsia opulenta (Silvestri) is one of the most effective parasitoids of the citrus blackfly, Aleurocanthus woglumi Ashby (Homoptera: Aleyrodidae). It was discovered by Silvestri on A. incertus collected in Van-Phu (Vietnam) (Silvestri 1927). In 1950, E. opulenta from Saharanpur (India) were released for the control of A. woglumi in Mexico (Flanders 1969). The parasite was then introduced to Texas in 1971 (Summy et al. 1983), and Florida in 1976 (Hart et al. 1978) to suppress and maintain under the economic threshold the population of the citrus blackfly in these states.

adult and parasitized blackfly pupal cases

Distribution

Encarsia opulenta has been reported as native to Asia (Vietnam and India) (Silvestri 1927, Smith et al. 1964), and was introduced to Barbados, Cuba, Salvador, Kenya, Jamaica, Oman, Mexico, Venezuela, and USA (Texas and Florida) to control the citrus blackfly. In Florida, the parasite is found in South and Central Florida where the citrus blackfly occurs (Nguyen et al. 1983).

Description

Female small (1.10 mm long). Thorax whitish to pale yellowish. Antennae 0.8 mm long, 8 segmented, and the 1st flagellum shorter than pedicel or other flagella. Wing slightly shady in the center. Abdomen with segments 3 to 6 dark brown, remainder yellowish. Ovipositor dark, 0.5 mm long. Male smaller than female (0.75 mm long) and different in color. Body and head of the males dark brown. Male antennae 8-segmented, with the 1st flagellum almost round and wider than the succeeding segment (Silvestri 1927, Grissell 1979).

adult female

adult male

Biology

The female can live longer than 30 days with adequate nutrition and displays good searching ability. A mated female lays a single diploid egg in any nymphal stage of the citrus blackfly, but prefers the second stage, and this egg will produce a female. Under laboratory conditions (24°C) the development from egg to adult requires 30 to 35 days. Virgin females lay haploid eggs in the fully developed larva of the E. opulenta female and produce males (adelpho-parasite). The sex ratio in the field is about 1:7 (male:female). E. opulenta is hyperparasitized by E. smithi (Silvestri) that was accidentally introduced to Florida by 1979. In Florida, E. opulenta and Amitus hesperidum (Hymenoptera: Platygastidae) coexist. The latter has a high rate of reproduction, and can produce 60 to 70 progenies per female; thus this species is very effective in suppressing high densities of the citrus blackfly. E. opulenta reproduces very slowly, and can maintain the population of A. woglumi at a low level in Florida (Nguyen et al. 1983, Nguyen and Sailer 1987, and Flanders 1969).

Hosts

Aleurocanthus woglumi Ashby and A. incertus Silvestri are the only hosts reported (Silvestri 1927, Smith et al. 1964).

adult male

Selected References

Author: Ru Nguyen, Florida Department of Agriculture and Consumer Services, Division of Plant Industry.
Originally published as DPI Entomology Circular 301.
Photographs: Division of Plant Industry
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-242
Publication Date: October 2001
Copyright 2001 University of Florida

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