INSECT CHITINASES - MOLECULAR-BIOLOGY AND POTENTIAL USE AS BIOPESTICIDES

Chitin, an insoluble structural polysaccharide that occurs in the exos keletal and gut linings of insects, is a metabolic target of selective pest control agents, One potential biopesticide is the insect molting enzyme, chitinase, which degrades chitin to low molecular weight, sol uble and insoluble oligosaccharides, For several Sears, our laboratori es have been characterizing this enzyme and its gene, Most recently, w e have been developing chitinase for use as a biopesticide to control insect and also fungal pests, Chitinases have been isolated from the t obacco hornworm, Manduca sexta, and several other insect species, and some of their chemical, physical, and kinetic properties have been det ermined, Also, cDNA and genomic clones for the chitinase from the horn worm have been isolated and characterized, Transgenic plants that expr ess hornworm chitinase constitutively have been generated and found to exhibit host plant resistance, A transformed entomopathogenic virus t hat produces the enzyme displayed enhanced insecticidal activity, Chit inase also potentiated the efficacy of the toxin from the microbial in secticide, Bacillus thuringiensis. Insect chitinase and its gene are n ow available for biopesticidal applications in integrated pest managem ent programs, Current knowledge regarding the molecular biology and bi opesticidal action of insect and several other types of chitinases is described in this mini-review, (C) 1998 Elsevier Science Ltd, All righ ts reserved.