Biological Pest Control: How Entomopathogenic Fungi Work

Entomopathogenic fungi are fungi that specifically infect and kill insects, and several species have been developed into biological pest control products. Unlike chemical insecticides, which typically act on contact or ingestion through a toxic compound, these fungi work through an infection process: spores land on an insect's cuticle, germinate, and penetrate through it directly, eventually colonizing the insect internally. Different species tend to specialize in different pests. Beauveria bassiana has a broad host range covering various insect pests found on vegetables, cotton and plantation crops. Verticillium lecanii (also classified under the genus Lecanicillium) is particularly effective against sucking pests such as aphids, whiteflies and thrips, and tends to perform best under humid conditions that favor fungal spore germination. Metarhizium anisopliae is a soil-dwelling species often used against pests such as white grubs and termites that spend part of their life cycle below ground. Because these are living biological agents rather than chemical toxins, their performance is influenced by environmental conditions — particularly humidity and temperature — as well as by application timing relative to the pest's life cycle. They are generally considered compatible with integrated pest management programs, since their relatively narrow host specificity means many beneficial and non-target insects are less affected than they would be by broad-spectrum chemical insecticides. As with any biological control agent, matching the right species to the target pest, and applying it under conditions that favor its establishment, are key to getting good results in the field.