"Our lab trials showed a 1% tea tree oil formulation reliably produced a 100% kill rate of lice and lice eggs, but we were pleased to see our pen trials generated the same results," says project leader Peter James of the Queensland Alliance for Agriculture and Food Innovation.
No lice were found two, six, 12 or 20 weeks after sheep shorn two weeks previously were dipped with the 1% tea tree oil formulation.
"We also tested sheep with longer wool and the results showed that jetting 1% and 2% tea tree oil formulations reduced louse numbers 94% in comparison to controls two weeks after treatment."
Besides killing maggots, lab work also showed the oil has a strong repellent effect against adult flies, preventing eggs being laid on the wool for up to six weeks.
"Tea-tree oil could be effective as a preventative treatment for wounds caused by mulesing, tail docking or any wound likely to be struck," James says. "It has also shown to have antibacterial properties and is suggested to have wound healing effects."
Use of natural products on a commercial scale is often hampered by variation in quality. But tea tree oil is well placed as its composition is already specified under an international standard, ISO 4730, notes James.
This ensures the supply of a consistent product, essential when using a product as an insecticide.
"Getting the formulation exactly right is vital and it's something requiring more research. It's not as simple as mixing tea tree oil with water and applying it to your sheep; it's a complex and exact science.
"More research needs to be done before we can definitively say tea tree oil is a viable treatment for fly strike and lice infestations, but these initial findings are encouraging."
The project was co-ordinated by Australia's Rural Industries Research and Development Corp.
