VACCINATION AGAINST LUCILIA-CUPRINA - THE CAUSATIVE AGENT OF SHEEP BLOWFLY STRIKE

The sheep blowfly, Lucilia cuprina, is responsible for over 80% of cas es of blowfly strike in Australia and the losses in production and she ep deaths due to flystrike exceed $200 million per annum. Traditional methods of control are becoming less effective because of the blowfly' s resistance to insecticides and thus other methods of control are nec essary. In general, sheep develop very little immunity to flystrike ev en after repeated infestation, however vaccination against L. cuprina has shown considerable potential for controlling flystrike. The most s uccessful sources of antigens have been the larvae's secreted protease s and several extracts from gut or peritrophic membrane. Immunization with these antigens results in retardation of larval growth and in som e cases larval mortality. On sheep immunized with peritrophic membrane extracts, the growth retardation appears to be caused by a blocking o f the peritrophic membrane which results in the larvae being starved o f nutrients. The prospects for vaccine development and the remaining b arriers to be overcome are discussed.