INVITATION PAPER (C.P. ALEXANDER FUND) - THE POTENTIAL OF BIOLOGICAL-CONTROL FOR MANAGEMENT OF GRASSHOPPERS (ORTHOPTERA, ACRIDIDAE) IN CANADA

In Canada biological control of grasshoppers has been studied since th e 1930s. Previous attempts at ''classical'' introductions have not bee n successful. Native parasitoids, especially sarcophagid flies, have a significant impact on grasshopper populations during certain times bu t the required conditions and regulatory potential are not understood. Sarcophagids, especially Kellymyia kellyi (Aldrich), and the mermithi d nematodes Agameimis decaudate Cobb, Steiner, and Christie and Mermis subnigricans Cobb have some potential as inundative agents. Invertebr ate predators appear to impact on egg and early-instar nymphal grassho ppers, and vertebrates, especially birds, help to regulate later insta rs and adults. The role of microbial pathogens in the population dynam ics of grasshoppers in western Canada has long been recognized, partic ularly with regard to entomophthoran fungi. The possibility of utilizi ng the microsporidan Nosema locustae Canning for suppression of grassh opper populations has been postulated since the 1970s and field evalua tions of its potential have been conducted in Saskatchewan and Alberta . More recently, considerable work, both basic and applied, has demons trated the potential of various fungus isolates pathogenic to grasshop pers as both ''classical'' and inundative control agents. Entomopoxvir us isolates from grasshoppers also show potential as biological contro l agents of grasshoppers but this potential has yet to be investigated in field situations. It is clear, however, that no single microbial p athogen will be the panacea of grasshopper control. It is suggested th at future biological control research focus on acquiring a better unde rstanding of the requirements and quantitative effects of parasitoids and predators on grasshopper populations. Emphasis should also be plac ed on developing integrated pest management programs that utilize loca l natural enemies (nematodes and microorganisms) for inundative contro l during outbreaks.