Hosts or Prey
Giant whitefly and certain other whiteflies
Identification
Evidence of their parasitism is the most recognizable sign that these tiny wasps are present. After the immature parasitoid completes its development and emerges as an adult wasp it leaves behind the empty covering of the dead whitefly with a round emergence hole:
- Encarsia noyesi (Aphelinidae) leaves a clear whitefly covering inside which the black cast skin of the immature parasitoid is visible.
- Entedononecremnus krauteri (Eulophidae) causes the whiteflies' pupal case to blacken.
- Idioporus affinis (Pteromalidae) leaves the whitefly covering hollow and pale yellow to whitish.
After a giant whitefly emerges from its pupal case the covering is white with an irregular or T-shaped slit, not a rounded hole.
Adults of each of the wasps are about 1/16 inch (1.5 mm) long with clear wings. Their body and the top of the head is mostly black to dark bluish and the bulging eyes are dark red.
Encarsia noyesii adults have yellow legs and yellow antennae with brown tips. Its most distinctive feature is an iridescent blue to yellow scutellum, a shield-shaped structure on top the back of the thorax that color contrasts with the parasitoids mostly dark body.
Entedononecremnus krauteri adults are especially stout wasps. They have an all black body, yellowish antennae, and black and yellow legs. A distinctive and unusual behavior of adult females is that although giant whitefly nymphs and pupae occur on the underside of leaves this parasitoid deposits her eggs from the upper leaf surface. Female wasps poke their ovipositor entirely through the leaf then into large nymphs or pupae of giant whitefly, which the wasp cannot see.
Idioporus affinis adults have antennae and legs that are yellow except for dark coloration at their base where they connect to the dark body. Unlike the dark abdomen of the other two wasps I. affinis has a mostly pale abdomen with some dark coloration.
Life Cycle
Wasps develop through four life stages: egg, larva, pupa, and adult. Only females are known for I. affinis and E. krauteri; they reproduce parthenogenetically (without mating). Each female wasp lays a single egg inside an immature (nymph, or instar) whitefly. Encarsia noyesi and I. affinis lay their egg in second through fourth instars. Entedononecremnus krauteri parasitizes only the third and fourth instars and prefers the fourth instar.
The hatching wasp larva feeds inside the whitefly nymph for about 2 weeks when temperatures are warm, then it kills the whitefly and pupates inside it. A few days later the new adult wasp chews a round hole in the whitefly cover and emerges.
Egg to adult development time is about 3 weeks when temperatures are warm. Each parasitoid species has several generations per year.
Habitat
Giant whitefly was inadvertently introduced into Southern California in 1992. It became a pest on over 60 species of crop and ornamental plants. In the fall of 1995, the California Department of Food and Agriculture made releases of the E. krauteri from Texas where the pest had earlier invaded.
Giant whitefly is apparently native to Mexico. Therefore entomologists from UC Riverside collected from Mexico E. noyesi and I. affinis and imported them for studies under quarantine. Beginning in 1997 the two wasps were released in California.
Encarsia noyesi and I. affinis are now relatively common in California wherever giant whitefly occurs. Entedononecremnus krauteri is relatively uncommon. Because of classical biological control by the parasitoids the giant whitefly is now difficult to find on most plant species where it formerly was a pest. The whitefly is still sometimes annoyingly abundant on its preferred hosts: begonia, giant bird of paradise, hibiscus, and xylosma.
To improve biological control
- Control ants because they attack natural enemies of various pests.
- Grow flowering insectary plants to provide nectar for adult natural enemies.
- Reduce dustiness that disrupts the activities of natural enemies (e.g., periodically hose off small plants).
- Avoid the application of broad-spectrum, persistent insecticides for all pests because they are toxic to natural enemies.
See Protecting Natural Enemies and Pollinators for more information.
Species
At least 30 species of Encarsia occur in California, many of which parasitize multiple species of whiteflies or other insects formerly called Homoptera. Encarsia noyesi parasitizes at least 11 species of whiteflies. Entedononecremnus krauteri and I. affinis each parasitize at least 2 species of whitefly.
More Information
- Bionomics of Aphelinidae, Annual Review of Entomology
- Host Stage Preferences of Encarsia noyesi, Idioporus affinis, and Entedononecremnus krauteri: Parasitoids of the Giant Whitefly Aleurodicus dugesii (Hemiptera: Aleyrodidae), UC Riverside, Environmental Entomology
- Scientists Pit Natural Enemies Against Giant Whitefly, California Agriculture
- Sharpshooter & Whiteflies: What’s New in Ornamental Research (PDF), UC Riverside
- Universal Chalcidoidea Database, Natural History Museum of London
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Hymenoptera
- Families: Aphelinidae, Eulophidae, and Pteromalidae
