Hosts or Prey
Whiteflies
Identification
Parasitoid presence is most recognizable by the change in appearance of parasitized hosts. Whitefly pupae that normally are pale yellow or whitish become bright lemon yellow then brown because visible through the whitefly covering are a yellow larva or brown pupa of E. pergandiella. When an adult E. pergandiella emerges from a host it chews a round exit hole in the whitefly's covering that is pale colored. Yellowish pellets of Encarsia feces (meconium) can also be visible in and along the sides of the empty host covering. When a whitefly emerges from its pupal case it leaves a ragged or T-shaped slit in a covering that is empty (contains no meconium).
The adult E. pergandiella has a lemon yellow or orangish head and thorax and clear wings. The top of the abdomen is brown and the underside is yellowish. The head has bulging eyes that are green. On top the head are three, tiny, red light receptors (ocelli) arranged in a triangle. The adult's body is about 1/50 inch (0.5 mm) long.
The egg is elongate oval and about 1/300 inch (0.08 mm) long. The larva is legless and maggotlike with distinct segments. The first instar (immature) has a last (rear) segment that is narrow and tail-like. The second and third instars lack the tail-like rear. The last instar and pupa are about 1/32 inch (0.8 mm) long. The pupa is brown and oblong. As it ages distinct appendages develop folded against the body.
Lookalikes
Many other parasitic wasps also attack whiteflies. For example when parasitized by Encarsia formosa the whitefly pupa blackens and the covering remains blackish after the adult wasp emerges. When Encarsia luteola parasitizes whiteflies they turn brown to yellow and after the adult wasp emerges the covering of the host is brownish.
Life Cycle
Adult female E. pergandiella will oviposit in all instars of whiteflies but prefer the third and fourth (last) instars. If an egg is laid in a first or second instar the parasitoid does not begin to develop and feed until the whitefly reaches the third instar.
Adult female E. pergandiella lay about 75 eggs during their lifetime, 1 egg per whitefly. The adult E. pergandiella emerges from the fourth instar (pupa) regardless of the instar in which an egg was laid. After hatching the wasp larva develops through 3 increasingly larger instars. The wasp pupates inside and the adult chews a hole in the host covering and emerges.
In addition to killing whiteflies by parasitizing them adult female E. pergandiella kill other whiteflies by host feeding. The female punctures whitefly nymphs with her ovipositor and consumes the exuding body contents, killing the whitefly without laying an egg in it.
Male E. pergandiella are parasitoids of immature female E. pergandiella or other wasp species that parasitize the hosts. This type of biology is called autoparasitism.
Encarsia pergandiella can be active throughout the year where winters are mild. Adults' lifespan is about 1 month when temperatures average 60ºF. Egg to reproductive adult development time is about 2 weeks when temperatures average 75ºF. Encarsia pergandiella has multiple generations per year.
Habitat
Encarsia pergandiella is believed to be native to California. For classical biological control of whiteflies, this wasp has been introduced in over 20 countries including Australia and parts of the Caribbean region and Europe.
To improve biological control
- Control ants because they attack Encarsia parasitoids and other natural enemies.
- Grow flowering insectary plants to provide nectar and pollen to feed 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.
For more information see Protecting Natural Enemies and Pollinators and the table of relative toxicities of insecticides and miticides to natural enemies and honey bees for specific crops.
Species
At least 30 species of Encarsia occur in California. Many of these parasitize multiple species of scale insects, whiteflies, or other plant-sucking insects formerly called Homoptera. Encarsia pergandiella parasitizes at least 34 species of whiteflies.
More Information
- Bionomics of Aphelinidae, Annual Review of Entomology
- Oviposition, Development, and Survivorship of Encarsia pergandiella (Hymenoptera: Aphelinidae) in Four Instars of Bemisia argentifolii (Homoptera: Aleyrodidae), Annals of the Entomological Society of America
- Studies With Whitefly Parasitoids of Southern California: I. Encarsia pergandiella Howard (Hymenoptera: Aphelinidae), The Canadian Entomologist
- Universal Chalcidoidea Database, Natural History Museum of London
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Hymenoptera
- Family: Aphelinidae
