Mealybug Leptomastix Parasitoid / Home and Landscape / UC Statewide IPM Program (UC IPM)

Hosts or Prey

Identification

The most obvious evidence of L. dactylopii or its relatives is the presence of mummified (parasitized) mealybugs, which are orange and puffy with a crusty outer covering. Mealybug parasitism becomes more apparent as the mealybug wax weathers away, exposing the oblong, mummified mealybugs. A hole or hinged cap is visible in mummies from which an adult parasitic wasp emerged. Note that mealybug mummies and parasitoid emergence holes are also produced by certain other parasitoid wasps including Anagyrus species and Leptomastidea abnormis.

The adult L. dactylopii is an orangish wasp 1/12 inch (2 mm) or less in length with dark, bulging eyes. Larvae are pale maggots that occur singly within host mealybugs. Mature larvae and pupae are each about 1/12 inch (2 mm) long. Pupae are oblong and as they age appendages develop folded against the body.

Life Cycle

Encyrtid wasps develop through 4 life stages: egg, larva, pupa, and adult. Adult females insert a single egg (oviposit) into a mealybug. The females prefer to oviposit in third (last) instars (nymphs) and young adult female mealybugs. Larvae feed inside for about 1 month, developing through 4 increasingly larger instars. When the host is eventually killed, the mealybug becomes an orange, crusty, barrel-shaped mummy. The mature larva then pupates inside the host.

The emerging adult wasp chews off an end of the mummified covering, sometimes leaving a caplike cover attached to or near the mummy. Adults can live for several weeks feeding on honeydew and nectar. Each female can parasitize about 60 to 100 mealybugs during her lifetime.

At warm temperatures egg to adult development time is about 3 weeks. Leptomastix dactylopii has several generations per year.

Habitat

Leptomastix can occur wherever its host mealybugs occur, including in field, tree, and vine crops, gardens, landscapes, and wildlands. The parasitoid prefers hosts in warm, sunny, humid environments, so it thrives in greenhouses and interiorscape plantings.

Commercial Availability

Leptomastix dactylopii is commercially reared and sold. It has been released in combination with the mealybug destroyer lady beetle (ladybug or ladybird beetle) to successfully control citrus mealybug in greenhouses and interiorscapes.

If purchase and release of L. dactylopii or the mealybug destroyer is being contemplated and to conserve resident natural enemies

Control ants because they attack natural enemies of mealybugs and other pests.
Grow flowering insectary plants to provide nectar and pollen to nourish adult natural enemies.
Reduce dustiness that disrupts the activities of natural enemies (e.g., irrigate overhead or periodically hose off small plants).
Avoid the application of broad-spectrum, persistent insecticides for all pests because they are toxic to natural enemies.

See the Selectivity of Insecticides and Miticides used in citrus to learn which pesticides are most compatible with biological control. See The Association of Natural Biocontrol Producers, Biological Control Organisms for Insects and Mites (PDF), Natural Enemy Releases for Biological Control of Crop Pests, and Protecting Natural Enemies and Pollinators for more information.

Species

Leptomastix dactylopii is the only member of this genus reported in the United States. It can parasitize at least 50 species of mealybugs. Important hosts of L. dactylopii include citrus mealybug, Comstock mealybug, grape mealybug, and longtailed mealybug.