Fact Sheets
Pest Management
Natural Enemies for Suppression of Greenhouse Pests
II. Parasites and Predators
Pests and Natural Enemies
Greenhouse whitefly (Triaulerodes vaporariorum) . This species of whitefly has been controlled effectively for decades in Europe on tomato and cucumber crops by early season inoculative releases of the aphelinid wasp Encarsia formosa. This species is not currently the whitefly of usual concern on flower crops. The main whitefly on flower crops is silverleaf whitefly.
Silverleaf whitefly (Bemisia argentifolii) . This is a new whitefly (since circa 1988) that is now the principal whitefly on flower crops, especially poinsettias. The commercial strain of Encarsia formosa provides partial control but is insufficient. New parasites under development against this pest are Encarsia "Beltsville" and Eretmocerus californicus. These wasps kill whiteflies two ways: parasitism and "host feeding" (acting like a predator and eating whiteflies).
Western flower thrips (Frankliniella occidentalis). Biological control options for this pest are not satisfactory yet. Agents under study include predatory bugs (Anthocoridae, Orius spp.) and predacious mites (Ambylseius cucumeris and Ambylseius barkeri) . These uses are still experimental on flower crops.
Spider mites (Tetranychus urticae and others). The predacious mite, Phytoseiulus persimilis is widely and effectively used for mite control. Use is not effective on all crops. Use on roses has been studied by John Sanderson at Cornell University.
Fungus gnats (Bradysia spp.) . Options include predacious mites (Hypoaspis miles), nematodes (especially Steinernema feltiae) and Bacillus thuringiensis var. israelensis. In our trials, mites were ineffective. Nematodes were comparable to chemical control with Duraguard. Bt has not yet been tested by our laboratory.
Shoreflies (Scatella stagnalis) . Biological control options are limited. Recent trials show that under laboratory conditions the nematode Steinernema feltiae was effective. Effectiveness in field trials depends on good timing (based on monitoring with potato plug baits) and regular applications.
Black vine weevil (Otiorhychus sulcatus) . A nematode product called Larvanem (Heterorhabditis sp. ) is available for control of the larvae of this pest in potted greenhouse plants.
Aphids (various species). The predacious midge Aphidoletes aphididmyza, and the aphid parasite Aphidius matricaria (and other species) are used for control of aphids. In Europe, the fungal pathogen Verticillium lecanii is also available, but is not registered for use yet in the United States.
Leafminers (Liriomyza spp.). The parasites Dacnusa sibirica, Opius pallipes and Diglyphus isaea are used for control of these pests. Choice of species depends on location of the greenhouse, with some species working best in northern locations and others better in southern locations.
Mealybugs (mainly citrus mealybug, Planococcus citri, and longtailed mealybug Pseudococcus adonidum). Beneficial Insectary of Oakland, CA, (800-477- 3715) will begin production in early 1996 of new species of parasitoids that have been studied in the laboratory of Mike Rose of Texas A & M University and been found to be highly effective. These are Leptomastix dactylopii for citrus mealybug; and for longtailed mealybug, Pseudaphysus angelicus and Anagyrus fusciventris. These will be new to the industry and come highly recommended.
Brown soft scale (Coccus hesperidum. Beneficial Insectary of Oakland, CA, will begin production in early 1996 of a new species of parasitoid, Netaphysus alberti, that has been studied in the laboratory of Mike Rose of Texas A & M University and been found to be highly effective.
Caterpillars Bacillus thuringiensis (Bt) products are available that provide satisfactory control for some kinds of caterpillars. Some species are not susceptible to existing Bt strains, but this is changing as new strains are commercialized.
Reference Materials
The Biology of Glasshouse Pests and Their Natural Enemies: Knowing and Recognizing. 1992. M. Malais and W. J. Ravensberg, authors. Published by Koppert, B. V., Berkel en Rodenrijs, the Netherlands (available through IPM Laboratories in Locke, New York 13092 [$44]). The best available book on specific natural enemies of pests of greenhouse crops, including information on their biology, recommended use patterns, and with good photographs and drawings for recognition.
Biological Pest Control: The Glasshouse Experience. 1985. N.W. Hussey and N. Scopes, editors. Published by Cornell University Press, Ithaca, New York 14853. Short readable summaries of the science, for each type of pest. Good access to the literature. Now a bit dated, but still good.
Suppliers of Beneficial Organisms in North America. 1994. C.D. Hunter, author. Published by California Environmental Protection Agency, Department of Pesticide Regulation, 1020 N. St., Rm. 161, Sacramento, CA, 95814-5604. A listing of suppliers and products, a valuable tool for ordering beneficial agents.
Prepared by:
Roy Van Driesche and Mark Hoddle
Greenhouse IPM Program
University of Massachusetts
Amherst
August 1995
