Under the microscope: Utilizing Encarsia formosa

Encarsia formosa is a wasp less than 1/16 of an inch long, but it does big work against pests in the greenhouse. E. formosa parasitizes at least 15 species of whiteflies, including greenhouse whiteflies and silverleaf whiteflies. If you haven’t added it to your IPM toolbox yet, it’s a successful biocontrol method. It’s one of the most commercialized natural enemies and used worldwide in controlled production systems for biological control of whiteflies on vegetables and ornamentals.

The kill

When searching for prey, E. formosa walks over the tops, edges and bottoms of the whitefly’s host plant. Upon finding a suitable whitefly nymph, this parasite either injects an egg into the nymph or punctures the nymph and drinks hemolymph that oozes out. Host feeding often kills the immature whitefly. 

Although E. formosa feeds on all the immature whitefly stages except the eggs, their preferred host stage may vary depending upon prey species. Pupae and second instar nymphs of greenhouse whiteflies are the preferred stage for feeding, while the pupae and nymphal instars are equally preferred with silverleaf whiteflies.

Adults chew a conspicuous hole in the upper surface of the dead nymph. Parasitized greenhouse whitefly nymphs turn black, while parasitized silverleaf whitefly nymphs darken slightly.

Each wasp kills about 95 whitefly nymphs during its life, either by feeding or oviposition. One study concluded that E. formosa can consume approximately 10 first and second instar or five third and fourth instar silverleaf whitefly during a 48-hour period, and their host feeding potential can be enhanced by depriving them of food before release. It’s best to release the wasps early in the infestation when the whitefly population is low.

Lifecycle

Females lay up to 10 eggs each day, although older E. formosa lay fewer. The wasp grubs hatch and mature into a new generation of adults in about three weeks.

Sources: North Carolina State University Extension, University of Florida Extension, University of New Hampshire Extension

Photo by David Cappaert