Encarsia formosa Whitefly parasite by Applied Bio-Nomics PO Box 1555, Ventura, CA 93002 800-248-2847 * 805-643-5407 * fax 805-643-6267 questions bugnet@rinconvitova.com orders orderdesk@rinconvitova.com web www.rinconvitova.com

Target pests

Greenhouse whitefly (Trialeurodes vaporariorum)

Silverleaf whitefly (Bemesia argentifolia)

Sweet potato whitefly (Bemesia tabaci)

Description

‘Encarsia’ is a tiny parasitic wasp that parasitizes whiteflies. It was the first biological control agent developed for use in greenhouses.

· Adults are black with yellow abdomen, less than 1 mm (1/20 inch) long (they do not sting).

· Larval stages live entirely inside immature whiteflies, which darken and turn black as the parasites develop inside.

Use as Biological Control

· Encarsia are effective controls for greenhouse whitefly on greenhouse cucumbers, tomatoes, peppers and poinsettias

· They can control silverleaf/sweet potato whitefly, but only under optimum management using high release rates.

· Optimum conditions are temperatures over 68° F (20° C), high light levels (7300 lux) and relative humidity 50-70%. When daytime temperatures are less than 64° F (18° C) Encarsia activity is sharply reduced, making them less effective.

· Do not attempt to use Encarsia if high whitefly populations are already established.

· The predatory beetle Delphastus avoids feeding on whiteflies parasitized by Encarsia, therefore it can be used with Encarsia.

· The parasitic wasp Eretmocerus californicus may also be used with Encarsia.

Monitoring Tips

Check the undersides of lower leaves for parasitized whitefly scales. They turn black (for greenhouse whitefly) or transparent brown (for sweet potato whitefly) so are easy to tell from unparasitized scales, which are whitish.

Parasite lays egg in 2 week-old whitefly scale	Parasite grows inside scale for 20-25 days	Mature parasite emerges, lives about 10 days.

Life Cycle

The complete life cycle takes about 28 days at 70^o F (21^o C). Temperature affects development rate; for example, larval development takes 15 days at 77° F (25° C) and 45 days at 15°C (59°F).

· Encarsia populations are all female (males sometimes occur but they are not functional).

· Eggs are laid in 2-week-old whitefly scales (second and third whitefly larval stages), one egg per whitefly. Most Encarsia are female and each lays up 10 eggs per day for an average of 200 eggs.

· Larvae develop inside the whitefly scale for 10 days (at 20-25°C).

· They pupate for another 10 days, then adults emerge by chewing a hole in the top of the scale. Adults are most active for about 10 days, although they can live up to 30 days.

In addition to parasitizing them, Encarsia kill whitefly scales by feeding on the host directly; they also feed on whitefly honeydew.

Product Information

Encarsia pupae are sold glued onto cards or loose scales.

For pupae on cards, it is important to hang the cards from lower leaves in the shade as Encarsia tend to fly upward; avoid wetting them while watering. If there are hanging baskets in the greenhouses, some cards must be placed on the baskets, as well as on plants on benches.

Adults will emerge from the pupae over a period of 1-2 weeks at 68-77^o F (20-25 °C).

Small emergence holes in the pupae are visible using a 5-10X lens and indicate that the parasite has emerged.

If necessary, the Encarsia pupae can be held for up to 2 weeks at 40-50^o F (5-10^o C), however the percentage of emergence will decrease with time.

Introduction Rates

General Introduction Rate

· 1-10 Encarsia/m² (10 ft²) or 1-5 Encarsia/infested plant, every 1-2 weeks for at least 5 introductions, or until 80% of whitefly scales are parasitized.

In commercial greenhouses, Encarsia are usually released, either:

· in low numbers before pests are present (called an inoculative release), or,

· in higher numbers after pest populations are established (called an inundative release).

Before whiteflies are detected (1 m² = 10 ft²)

· Tomato, cucumber – 1.5 Encarsia/m², weekly

· Sweet pepper/egg plant – 0.5 Encarsia /m², weekly.

After whiteflies are established:

Number of whiteflies/week counted on yellow traps	Tomato, Pepper, Eggplant Release rate/m^2/week	Cucumber Release rate/m^2/week
1-4	2	3
5-8	4	6
over 8	8	10

Note: Above rates must be at least doubled for control of silverleaf/sweet potato whitefly or if temperatures are 66^o F (18° C) or less.

Encarsia tend to remain in regions where the whitefly are concentrated, therefore it is important to distribute them well throughout the greenhouse:

· For inoculative releases, spread introductions over 40 or more release points per 10,000 ft².

· For inundative releases, use 60 or more release points per 10,000 ft² (1,000 m²) and place more where whiteflies are found.

Once the percentage of parasitized scales exceeds 80%, the number of Encarsia present should be enough to control greenhouse whitefly.

For Best Results

· The whitefly species in a crop must be correctly identified to make sure it is a species that Encarsia can control and to determine the correct release rate.

· Eliminate whitefly from alternate plant sources, such as weeds or previous crops, and from cuttings before Encarsia releases begin.

· High whitefly populations hinder movement of the parasite as does the presence of excessive amount of honeydew. Remove whiteflies and honeydew by spraying with water or 1% Safer’s^® insecticidal soap.

· When de-leafing tomato plants, do not remove leaves that have significant numbers of black (parasitized) whitefly scales. If leaves must be pruned from plants, retain them in the greenhouse, under the plants, until the wasps have emerged (1 to 2 weeks).

Using Pesticides

Encarsia are extremely sensitive to insecticide residues. Plastic covering or flooring used in greenhouses may harbor residues at levels that are harmful to this parasite for over 6 months. If, after a month of introducing Encarsia, whitefly parasitism is not occurring, contact supplier for assistance.

Spreader stickers in spray applications are harmful to Encarsia.

· If whitefly hot spots develop, spot spray with Safer’s soap (1% solution), weekly, directing the spray onto new leaves to kill adult whiteflies and early stages of scale.

· Kinoprene (Enstar^®) may also be used on ornamental crops.