For high levels of whitefly population use Encarsia Formosa in conjunction with Delphastus
This tiny predaceous beetle is being developed for whitefly control. It works best at high population levels of whitefly, higher than most growers would find acceptable within a crop. The adults must feed on at least 10 whitefly eggs per day in order to continue their own egg production. Both the adult and larval stages feed on whiteflies. Introduction rates range from 1 Delphastus per infested plant or 5-10 per 10 square feet. Delphastus alone will not be able to reduce whitefly populations to acceptable levels. A program involving Encarsia as well will likely be necessary.
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.