Pest management of soil-inhabiting insects with microorganisms

Abstract

Although more than 90% of insects have a stage in the soil, there are very few microorganisms now being used to manage soil insects. The first successful use of a microorganism for suppression of a pest was the utilization of milky-disease bacteria, Bacillus popilliae Dutky, for control of Japanese beetle larvae in turf. More extensive use of this bacterium has been hampered by its narrow host range, slow build-up in the soil, and an inability to produce it in vitro. Recent developments may have solved the production problems and will open up increased use of B. popilliae products. Although various strains of Bacillus thuringiensis Berliner are available for control of foliage-feeding Lepidoptera, aquatic Diptera, and the Colorado potato beetle, none have found a use in the soil environment. Other bacteria, such as Serratia spp. are being examined for control of the grass grub in New Zealand. Fungi are often associated with dead and dying insects in the laboratory and field. Both Beauveria spp. and Metarhizium anisopliae (Metschnikoff) Sorokin are used in pest-management programs in South America, Europe and Asia, but not primarily for control of soil-inhabiting insects. Beauveria has the potential for future development against a number of pests in the U.S.A. Viruses are available for control of several pine-feeding sawflies and certain lepidopterous pests. They are also important in the management of Oryctes rhinoceros (L.), a pest of coconut palms. Although protozoa have been detected in numerous soil insects, they do not appear to have much potential for direct use in pest management. One exception is the use of Nosema locustae Canning for control of grasshoppers in the Western U.S.A. and in Africa. If microorganisms are to be utilized to their full potential, we need to fill in the gaps in our knowledge of the soil ecology.