Encarsia Formosa, Eretmocerus eremicus, Delphastus catalinae, Amblyseius swirskii for whitefly control.
Encarsia formosa has been used as a natural pesticide to control whitefly populations in greenhouses since the 1920s. Use of the insect fell out of fashion due to the increased prevalence of chemical pesticides and was essentially non-existent by the 1940s. Since the 1970s E. formosa has seen something of a revival, with renewed usage in greenhouses. E. formosa is used for whitefly control in greenhouses on tomatoes, strawberries and in floricultural and nursery plants. Biological control of the greenhouse whitefly can often be provided in enclosed areas by introducing sufficient numbers of commercially available E. formosa. Release programs of Encarsia formosa are most effective when the initial population of whiteflies is quite low (only a few whiteflies per plant) and long-residual insecticides have not been applied in advance of the parasite release. For biological control to be successful use more selective and less persistent insecticides, and control ants since they disrupt the oviposition of E. formosa.
Encarsia formosa, an endoparasitic wasp, is the most important parasite of the greenhouse whitefly. Adult female Encarsia formosa are tiny wasps with a dark brown to black head and thorax and a bright yellow abdomen. Males are dark in color but are rare. Adult females host feed on all immature stages by puncturing the body with their ovipositors and consuming the exuding blood. Eggs are laid into third and fourth-instar whiteflies and hatch into larvae that feed within the whitefly nymph and grow through three larval instars before killing the host. Greenhouse whitefly nymphs turn dark brown or black approximately one week after being parasitized and their skin forms a black pupal case for the parasite. Silverleaf whiteflies parasitized by E. formosa stay lighter in color and do not turn black.
Delphastus catalinae is considered an effective biological control agent for whiteflies because of its high prey consumption rates, long adult survival, and high reproduction rates. Delphastus is used to control whiteflies in tropical and semi-tropical plants as well as commercial greenhouses. The predators avoid feeding on parasitized whiteflies, therefore is compatible with whitefly parasites such as Encarsia and Eretmocerus species. Delphastus also tends to feed in high density whitefly populations, while parasites do best at lower densities. Further, Delphastus prefer feeding on whitefly eggs. Optimum conditions are moderate to high temperatures of 61-90°F (16-35°C), but Delphastus do not fly at temperatures below 55°F. They do not enter diapause under short-day conditions, therefore remain active all season. Target Pests: Greenhouse whitefly, Banded-winged whitefly, Sweet potato whitefly, Silverleaf whitefly, Woolly whitefly, Azalea and Hibiscus whitefly, Cloudywinged, citrus and rhododendron whitefly and Citrus blackfly.
Eretmocerus eremicus is a tiny parasitic wasp (~1 mm in length) that is indigenous to the southern desert areas of California and Arizona and is an important parasitoid of whiteflies in these areas. Adults live for 1-2 weeks and lay approximately 100-200 eggs during their lifetime. Most of these eggs are laid within the first few days after emergence from their pupal cases. These numbers however are quite variable and depend on a number of factors such as temperature, host whitefly and host plant of the whitefly.
Although these wasp species will host feed on all 4 whitefly instars, they prefer to parasitize 2nd and 3rd instars, laying their eggs underneath the larvae. The wasp larva then enters the whitefly after hatching. The effectiveness of this wasp is due to both parasitism and host feeding by the adult. Host feeding is necessary for egg development and an individual Eretmocerus female can kill up to 30 GWF nymphs/day.
Target Pests: E. eremicus attacks whiteflies, including greenhouse whitefly, sweetpotato whitefly, silverleaf whitefly, and bandedwinged whitefly.