Whitefly Parasite: Encarsia formosa
Encarsia formosa is a tiny (0.6mm) wasp that attacks only whiteflies. Adult female Encarsia kill whitefly scales in two ways: by puncturing and feeding on scales, or laying their eggs in scales (each female may produce 30-500 eggs during her lifespan). Encarsia eggs hatch into tiny larvae, which cause the whitefly pupae to turn black as the young wasps mature. At 70°F, a new adult wasp emerges about 21 days after the egg is laid. The parasites are shipped inside the blackened whitefly scales which are attached to cards in batches of 50-100 per card.
Target pests: Greenhouse whitefly, and mixed greenhouse/silverleaf whitefly populations.
Favorable environment: Daily average temperature above 64° F, supplementary light in winter, 70% RH . At temperatures above 70° F, Encarsia develop faster than whitefly.
Release Strategy: Release Encarsia at the first sign of whiteflies on yellow sticky cards. Release at 1-2 week intervals for 6-8 weeks.
Preventive: 1 per 6 sq.ft. biweekly
At 1st whitefly sign: 1 per 3 sq ft/wk for 3-6 wks.
Up to one whitefly per plant: 1 per sq ft/wk for 6 wks.
Poinsettias: 0.1 or more /plant weekly, combined with the release of Eretmocerus below. If used alone on poinsettias, use 2 or more per plant weekly.
Cucumbers: 20,000/acre weekly, 3-3+ times
Tomatoes: 10-20,000/acre (1 per 2-4 plants) weekly, 3-3+ times
Whitefly Predator: Delphastus catalinae
This minute black lady beetle has a voracious appetite for whitefly eggs, scales, and adults. Each beetle is about the size of the bottom half of this “8″. The beetle matures from egg to adult in about 3 weeks at 80°F. Females will live for about 50 days, laying 3-4 eggs per day, if well supplied with whitefly prey. They require 100-150 whitefly eggs per day to maintain egg-laying. They eat about eleven whitefly scales per day, or from 150-640 whitefly eggs per day. Delphastus beetles complement Encarsia and Eretmocerus biocontrol programs. They do not eat parasitized whiteflies.
Target pests: Greenhouse and silverleaf whitefly
Favorable environment: 65-90° F
Release strategy: Concentrate releases of adults near areas of high whitefly populations so that beetles have sufficient food for reproduction and establishment. Subsequent generations will disperse through the greenhouse and provide control in other areas.
Application Rates: These release rates serve to inoculate a whitefly infestation with beetles. Use ½ to 1 per sq ft, but concentrate at least 25 beetles per release site.
Silverleaf Whitefly Parasite/Predator: Eretmocerus eremicus
Eretmocerus eremicus is the first parasite specifically adapted to silverleaf whitefly (Bemisia argentifolii), formerly known as the B strain of the sweet potato whitefly (Bemisia tabaci). Eretmocerus lays its eggs under small young scales of silverleaf whitefly. It differs from the greenhouse whitefly parasite, Encarsia formosa, which lays eggs directly into the whitefly scale. We recommend Eretmocerus on vegetables and foliage plants where silverleaf whitefly is the predominant species. This new biocontrol does not reproduce on poinsettia, but it may provide complete control of whitefly infestations when used properly. Hoddle, Van Driesche and others at U. Mass. recently found that a release rate of 1-3 Eretmocerus /plant/wk. gave better than 95% control of silverleaf whitefly on poinsettias. Eretmocerus is used in European greenhouses with good success.
Favorable environment: Native to desert areas of California & Arizona; tolerant of higher temperatures than Encarsia. 75°-100°F.
Release strategy on poinsettias: Before whitefly detected or with very low levels, 2-3/10 sq ft/week. With whitefly, 1 or more /plant/wk.
For other crops, try doubling Encarsia rates (Encarsia is nearly 100% female). Avoid getting release material (sawdust or bran) wet by using Release Points™ or other careful placement.
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