ECTOPARASITES OF LIVESTOCK IN NEW-ZEALAND

Ectoparasites (blowflies, lice, ticks, and mites) are not the main thr eat to farm production in New Zealand but are major concerns to the fa rmer and are a drain on resources. Lice and blowflies have been presen t from the earliest days of pastoral agriculture in New Zealand, as wa s the scab mite, Psoroptes ovis, supposedly extinct since the 1880s. T he cattle tick, Haemaphysalis longicornis, was a later addition to New Zealand's arthropod pest fauna, which has been extended further by th e relatively recent introduction of the Australian sheep blowfly, Luci lia cuprina. Lesser players such as the sheep ked (Melophagus ovinus), mange mites (Chorioptes spp., Psorergates ovis, Psoroptes spp., Demod ex spp.), and a bot fly (Oestrus ovis) add their tiny din as backgroun d noise to the orchestrated effects of the main players. Estimates of the monetary losses due to ectoparasites can be computed, but their lo ng-term value is doubtful - particularly when seen against a backgroun d of fluctuating world prices and occasional reversals of differential values between, say, carcase and by-products. Flystrike alone is esti mated to cost >$30 million annually. To this can be added the losses d ue to other ectoparasites. In the light of these costs it is clear tha t the <$1 million currently spent annually on research demonstrates hi gh cost-effectiveness. However, given the continuing application of pe sticides (and the attendant drain on overseas funds to purchase them), plus the labour associated with preventing or alleviating ectoparasit e damage, and the production losses or deaths that cannot be Prevented , a net loss to farming due to ectoparasites cannot be denied. This pa per briefly examines the historical aspects of the ectoparasites of li vestock in New Zealand, and follows with a view of their current preva lence, geographical distribution, and economics. Next there is a discu ssion of the management (''control'') methods currently employed, cons idering topics such as insecticide resistance, biological control, mol ecular biology, and rural sociology. Finally, I attempt a glimpse into the future, based on the assumption that unrestricted use of insectic ides may no longer be an option for agriculture within the next 20 yea rs, or sooner.