Delphastus catalinae

Description

Delphastus is a specialized whitefly predator in the lady beetle family. Adults are tiny, 1/15 inch long, dark brown to black, hemispherical beetles. Females have reddish yellow heads, lighter colored than males. Larvae are elongated, cream colored, covered with short fine hairs and have conspicuous legs. the adult beetles fly, while larvae are slow moving and travel from plant to plant on leaves.

Target Pest

Greenhouse whitefly (Trialeurodes vaporarium), banded-winged whitefly (Trialeurodes spp.) sweetpotato whitefly, silverleaf whitefly (Bemisia spp.), woolly whitefly (Aleurothrixus floccosus), azalea and hibiscus whitefly (Pealius spp.) cloudywinged, citrus and rhododendron whitefly (Dialeurodes spp.) citrus blackfly (Aleurocanthus woglumi).

Use in Biological Control

Delphastus is used to control whiteflies in tropical and semi-tropical plantings as well as commercial vegetable greenhouses. Delphastus avoids feeding on parasitized whiteflies, therefore it is compatible with the use of Encarsia and Eretmocerus whitefly parasites. Delphastus also tends to feed in high density whitefly populations, while parasites do best at lower densities of whiteflies. Delphastus adults prefer feeding on whitefly eggs. Optimum conditions are moderate to high temperatures of 61-90ºF. Delphastus do not fly below temperatures of 55ºF. Delphastus do not enter diapause under short-day conditions, and therefore remain active all season.

Life Cycle

The complete life cycle takes about 3 weeks at 78-86ºF. Eggs are yellowish ovals, laid on end, in clusters on the underside of leaves. Females lay 2-6 eggs per day and can lay over 300 eggs in their 65 day lifetime. Females must eat 100-150 whitefly eggs per day to initiate and sustain egg laying. Larvae feed for 7-10 days. Older larvae migrate down the plant to pupate. Pupae are often found clustered along leaf veins on the undersides of leaves. Adults emerge from pupae in 6 days. Adults can eat 150-640 whitefly eggs or 11 large larvae per day. A single beetle can consume as many as 10,000 whitefly eggs or 700 larvae during its lifetime. Both adults and larvae feed on whitefly eggs and immature stages. If food is scarce, they will also feed on other small arthropods, such as spider mites and aphids, and will cannibalize their own species.

Monitoring Tips

Inspect the undersides of leaves in whitefly 'hotspots' for all stages of beetles. Three weeks after the first introduction, expect to see larvae and pupae on the undersides of leaves. After 4-5 weeks, the first beetles should be found feeding on whitefly eggs among the adult whiteflies. Two months after the first introduction, all stages of Delphastus should be present in the oldest whitefly infested areas.

Product Information

Delphastus are sold in small containers of 100-500 adults. They are shipped in shredded paper or other packing material to protect them during transport. Mortality in these containers should be less than 10%. Once beetles warm up they become active immediately, and should be released as soon as possible. If necessary, beetles can be stored for 1-2 days at 50-61ºF but longer storage will reduce egg laying.

Introductory Rates

Introduce Delphastus in whitefly infested areas of the greenhouse as soon as whiteflies are detected. For use in greenhouse cucumbers, peppers, tomatoes, poinsettia, tropical plantscapes and more.

Low Rate-Release at least 100 Delphastus/whitefly 'hot spot' or 10 adults/infested plant, or .5 beetle/10ft2, weekly for 3-4 weeks.
Moderate Rate-500 Delphastus/whitefly hot spot or 1-2 beetles/10ft2 weekly for 4 weeks
High Rate-500 Delphastus/whitefly hot spot or 3-4 beetles/10ft2, weekly until established in all infested areas.

For Best Results

Best results are achieved when Delphastus is used together with whitefly parasites (Encarsia and Eretmocerus). Delphastus do not survive in the absence of prey, therefore should be released only after whiteflies are detected. Check for Delphastus when de-leafing or pruning leaves from infested plants. Keep any leaves with Delphastus pupae in the greenhouse until adult beetles have emerged. Use Amblyseius cucumeris along with other thrips predators such as Orius on flowering plants and Stratiolaelaps to control thrips pupae in the growth media.