Climate change, in the form of global warming, is a current concern and because farming systems, livestock parasites and their hosts are influenced by the weather, it is possible to predict (albeit with some uncertainty) changes in these in some broadly descriptive fashion, as climate changes. This review examines the on- and off-host responses to potential changes in temperature and humidity of a representative selection of arthropod ectoparasites (sheep chewing louse, Bovicola ovis; sheep blowflies, Lucilla spp., Calliphora stygia, and Chrysomya rufifacies; cattle tick, Haemaphysalis longicornis; scrotal mange mite, Chorioptes bovis; cat flea, Ctenocephalides felis; and dog flea, Ctenocephalides canis) that occur in New Zealand and in many other countries, and how these environmental factors can be perturbed by host manipulation. The bioclimatic preferences of the parasites are examined in relation to future broad climate parameters and how parasite life cycles, seasonality and population dynamics may be influenced. Likely adaptations of farming systems to meet climate change imperatives are briefly discussed. Collectively it is estimated that regions of New Zealand faced with warmer, wetter conditions under climate change may see an increase in flystrike and cattle tick prevalence, and perhaps an increase in the biting louse, but fewer chorioptic mange and flea infestations. In contrast, drier, warmer regions will possibly experience fewer ectoparasites of all types with the exception of flea infestations. Economic effects of increases in ectoparasite prevalence, using approximate dipping costs as a model are examined, and risks posed to New Zealand by some exotic arthropod parasites with the potential to invade under climate change, are briefly outlined.
Keywords: Sheep biting louse; blowflies; cattle tick; chorioptic mange; climate change; fleas.