Tip Top Bio-Control Technical Bulletin

Delphastus Pusillus (catalinae)
Whitefly Exterminator

Target Pests:
Greenhouse Whitefly (Trialeurodes vaporariorum)
Banded-winged Whitefly (Trialeurodes spp.)
Sweet potato Whitefly, Silverleaf whitefly (Bemisia spp.)
Woolly Whitefly (Aleurothrixus floccosus)
Azalea and Hibiscus Whitefly (Pealius spp.)
Cloudy-winged, Citrus and Rhododendron Whitefly (Dialeurodes spp.)
Citrus Blackfly (Aleurocanthus woglumi)

If whiteflies are scarce, they will also feed on other small arthropods, such as spider mites, broad mites and aphids.

Description:
Delphastus is a specialized whitefly predator in the lady beetle family.
The White Fly Predatory Beetle is a native beetle often found associated with high populations of various species of White Fly. Adults are small, shiny, and are approximately 1.3 - 1.4 mm in length (1/15th inch). Adults are dark brown to black, hemispherical beetles; females have reddish yellow heads, lighter color than males. Development is about a month long and females lay 3 - 4 eggs per day. Eggs are transparent and are twice as long as they are wide. It is mandatory for mated females to consume 100 - 150 eggs a day in order to oviposit. Each larval stage takes about 3 - 5 days to complete, and the pupil stage takes 6 days. Larvae are elongated, cream colored, covered with short fine hairs and have conspicuous legs. The pupae are more yellow and circular. On cloudy and twilight days, adults are most noticeable. The adult beetles fly, while larvae are slow moving and travel from plant to plant on leaves.

The complete life cycle takes 21 - 25 days. 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.

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 is compatible with the use of Encarsia spp. and Eretmocerus spp. whitefly parasites. Delphastus also tends to feed in high density whitefly populations, while parasites do best at lower densities of whiteflies.

Optimum conditions are moderate to high temperatures of 16°-35 °C (61°-90°F); Delphastus do not fly at temperatures below 13°C (55°F).
Delphastus do not enter diapause under short-day conditions, therefore remain active all season.

Feeding:
Delphastus prefers the egg stage of whiteflies and is therefore mainly present in the top of the plant. 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, broad mites and aphids though influence of these foods on reproduction is unknown.

Product information:
Delphastus are sold in small plastic containers of adults only. They are shipped in shredded paper or other packing material to protect them during transport. A small amount food and water is added to the container.

Release Rates:
Introduce Delphastus in whitefly infested areas of the greenhouse as soon as whiteflies are detected. Release the beetles at sundown on the day that they arrive with an inoculation of one beetle per 50 to 100 square feet of canopy to establish them. Ideally, you should inoculate when there are less than six white fly immatures per leaf keeping temperatures between 65° - 90° F, while adults can tolerate a temperature of only 45° to 105°F. Releasing a colony near each other and close to food works well to enhance mating and egg laying of the first generation. Right when the second generation begins to emerge, you can spread them around. At this point, you will begin to see control.

If you don't spray a heavy infestation, the beetle will soon take over. Each generation is approximately 50-100 times more numerous than the one before it. Once three weeks have passed, 100 beetles can become 10,000 and when six weeks have gone by, they become 1,000,000. Unfortunately, once that amount of time has soon gone by, the plants can be destroyed. Preferably, you should start early or knocking down with a short residual pesticide. Delphastus do not survive in the absence of prey, therefore should be released only after whiteflies are detected.

Chemical and Mechanical:
Broad spectrum and systemic insecticides are toxic to Delphastus.
Spreader-stickers and wetting agents may harm the beetles on contact, but do not have residual effects.

Insecticidal soap and kinoprene (Enstar®) may be used in whitefly hot spots, however, reducing whitefly numbers with pesticides also reduces the beetle's food supply and reproductive ability.

All resistance's are unknown and residue could take a very long time to break down, so that the inoculations are positive to survive. When infestations reach the point where they're very severe, some advisable ways for knockdown are: vacuums, sticky barriers or pesticide treatment. Seperate inoculated plants from the other infested plants that have been treated with pesticides and other chemicals for at least one week. The colony that was transferred will keep the infestation down and reduce it even further.

Biological:
Beetles are also compatible with parasitic wasps, such as Encarsia formosa for greenhouse whitefly, or Eretmocerus eremicus. Another option to consider would be to combine a strategy using one of these parasitic wasps as well. Beetles can detect parasitized whitefly nymphs and will tend to avoid feeding on these in favor of un-parasitized whitefly. Before Delphastus inoculations, Green lacewing can be released at low whitefly densities allowing a generation or two of lacewings to manage pests early. Relative to plant-feeding host foods, such as aphids, mealybugs and whitefly.

Strategic Considerations:
Pesticides and even wetting agents and spreader-stickers may adversely affect Delphastus survival. Broad spectrum and systemic insecticides are toxic to Delphastus.

* Colonies of beetles originally obtained from Florida as Delphastus pusillus have subsequently been identified as Delphastus catalinae, based on a revision of this group by R. D. Gordon.