Boring-insects as factors in tropical industries

Abstract

The economic importance and cryptic nature of lepidopteran stalk borers, mainly in the families Crambidae and Pyralidae, closely followed by the Scarabaeidae and Cercopidae, in sugarcane agriculture, has prompted extensive research into their control using entomopathogenic bacteria, viruses, fungi and nematodes. Bacillus thuringiensis (Bt) has been the most widely applied and field-tested, topical bioinsecticide and other control strategies have included: Bt delta-endotoxins expressed in plant-associated bacteria and in transgenic sugarcane lines. Most Latin American countries, followed by India, Australia, and some India Ocean Island countries, have been active in the research and development of entomopathogenic fungi to control sugarcane pests. Metarhizium anisopliae s.l. is the most commonly used pathogen for the augmented control of sucking pests in the hemipteran families: Cercopidae, Delphacidae, Lophopidae and Aphididae, some lepidopteran stalk borers, and Scarabaeidae. This is followed by Beauveria bassiana, used to control various hemipterans, some lepidopteran stalk borers (with an emphasis on discovering and developing endophytic strains of this fungus), and other coleopteran soil pests and termites; in India and South Africa, Beauveria brongniartii is being developed to control Scarabaeidae. Few augmented control programs using B. bassiana, B. brongniartii, and M. anisopliae against stalk borers have been undertaken, and most programs are still in the laboratory and field testing stages in developing countries. This is in contrast to the augmented use of these fungi for Scarabaeidae control in Australia and Reunion Island and Cercopidae (spittle bugs) in Latin America. Entomopathogenic nematodes are gaining attention, as seen by the number of recent studies and mass production systems in India and Brazil. The augmented use of viruses and nematodes are proportionally low compared to Bt and fungi for stalk borers, but entomopathogenic nematodes are more commonly used against Scarabaeidae.