Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________Major Natural Enemies of Eggplant Insect PestsSome common insect-pathogenic fungi:• Beauveria bassiana: this fungus is found naturally on some plants and in the soil.It is commonly found infecting soil inhabiting insects. It needs warm, humidweather for spread and infection. Infected insect larvae eventually turn white orgray. This fungus has a broad host range: it can infect larvae of rice insects likeblack bugs and rice seed bugs but also pests of other crops like corn borer,Colorado potato beetle and Mexican bean beetle. It is being tested for use againstmany other pest insects. Unfortunately, some natural enemies such asladybeetles can be susceptible to Beauveria. One possible application methodthat may avoid harming beneficial insects is the use of fungus-contaminated insectbaits that are only attractive to pest species. In Indonesia (West Sumatra),Beauveria is used as a spraying solution for control of different pest insects in chili(FAO Dalat report, 1998).Jassid infectedwith Beauveria• Entomophthora sp.: these fungi are fairly specific with regard to the groups of insects affected.Susceptible insects include aphids and several species of flies (in case of Entomophthora muscae).• Metarhizium species: are being tested as natural enemies of corn rootworm, white grubs, some rootweevils and several other pest insects. It has a very broad host range and most species occur widelyin nature. Metarhizium anisopliae (also known as Entomophthora anisopliae) can be used to control arange of coleoptera and lepidoptera pests. Metarhizium can be an important control agent of aphids.In Indonesia (West Sumatra), Metarhizium is used as a spraying solution for control of different pestinsects in chili. In Philippines, Metarhizium effectively reduced populations of rhinoceros beetles incoconut (FAO Dalat report, 1998). Metarhizium is commercially available as a foliar spray. See “TheBiopesticide manual” (BCPC, 1998) for product names and manufacturers or check internet sitessuch as www14 and www15 (see Reference list).• A species of Paecilomyces was found infecting whiteflies on cabbage in Cebu, Philippines.Researchers from the Regional Crop Protection Center have isolated the species and are now massproducingit on artificial media (FAO Dalat report, 1998). In other countries, for example USA,Paecilomyces fumosoroseus is commercially available for whitefly control. It can be applied as aspore solution and it has some activity against aphids, thrips and spider mites.• Verticillium sp. is used in Europe against greenhouse whitefly, thrips and aphids, especially ingreenhouse crops where controlled environment favors fungus effectiveness. Verticillium lecanii iscommercially available in Europe and USA for the control of greenhouse whitefly.☺ It is not important to know all the scientific names of insect-pathogenic fungi! ☺What is important is that you can recognize them in the field and realize that they are killinginsects and this is to the benefit of the farmer!Mode of action and symptomsFungi penetrate the skin of insects. Once inside the insect, the fungus rapidly multiplies throughout thebody. Death is caused by injury to the tissue or, occasionally, by toxins produced by the fungus. Thefungus emerges from the insect’s body to produce spores that can sometimes be seen as a “dusty”appearance. When dispersed by wind, rain or contact with other insects, the spores can spread theinfection.Infected insects stop feeding and become lethargic. They may die rapidly, sometimes in a position stillattached to a leaf or stem. The dead insect’s body may be firm or it may be an empty shell. The fungus isoften seen as “hairs” or “dust” in various colors around the insect’s body or on parts of the body.EffectivenessInsect-pathogenic fungi usually need moisture to cause infection. Natural infections are therefore mostcommon during the wet season. The effectiveness of fungi against insect pests depends on manyfactors: having the correct fungal species with the susceptible insect life stage, at the appropriatehumidity, soil texture (to reach ground-dwelling insects), and temperature. The fungal spores which can112Eggplant Ecological Guide