Progress towards development and adoption of integrated management systems against flystrike and lice in sheep.
Ectoparasites of sheep, principally blowflies [Lucilia] and lice [Bovicola], cost the New Zealand farming industry an estimated $60 million each year. This figure includes the cost of chemicals and labour used to treat or prevent flystrike and lice, together with the lost production. An Integrated Pest Management (IPM) trial project involving four groups of farmers (overall total 15) in four regions of New Zealand has been set up with the aim of adopting a holistic approach to managing these parasites and already early benefits have accrued to the farmers involved. Procedures were set up to reduce insecticide residues in wool by using techniques such as jetting which apply less chemical to the sheep but target it more appropriately and maintain or improve protection against flystrike and control of lice. As a consequence, savings in chemical and labour costs have been made. On two farms in particular, savings on these items ranged from $578 (27% reduction) on a property with 2000 Corriedale ewes to $3608 (52% reduction) on the other property with 8000 Romney ewes. An understanding that clean, healthy sheep, free of nematodes and dags, are less susceptible to flystrike and lice has also assisted in controlling the diseases. This paper also discusses the potential for biological control against blowfly populations, with large fly traps, sterilising baits and parasitoid wasps all being investigated. Research continues on specialist pastures such as birdsfoot trefoil (Lotus corniculatus) and sulla (Hedysarum coronarium) to evaluate the practicalities of incorporating their use in management systems for both nematode and flystrike control.