The good oil

A tea tree plantation in Coraki, NSW

While researching the development of new products and markets for Australia’s tea tree oil industry, scientists from the Rural Industries Research and Development Corporation found tea tree oil is an effective and environmentally benign treatment for fly strike and lice infestations in sheep.

Already widely recognised for its medicinal properties and use as an insect repellent for humans, the study’s results suggest tea tree oil derived from Melaleuca alternifolia could also prove to be a commercially successful veterinary treatment for use in the sheep and wool industries.

In the team’s laboratory trials, solutions containing one per cent tea tree oil consistently resulted in a 100 per cent kill rate of first stage maggots. There was also strong evidence to suggest the solution repelled adult flies, with no eggs being laid on the wool for up to six weeks.

Lead researcher Peter James from the Queensland Alliance for Agriculture and Food Innovation said the results were particularly encouraging.

“Our lab trials showed that a one per cent tea tree oil formulation reliably produced a 100 per cent kill rate of lice and lice eggs, but we were very pleased to see that our pen trials generated the same results,” James said.

Shorn sheep used in the trials were inspected at two, six, 12, and 20 weeks after being dipped in the one per cent tea tree oil solution, but at no point were lice found in the wool. Animals with longer wool were also tested, using both one per cent, and two per cent solutions. In all cases results showed a significant reduction in louse numbers and wool damage in comparison to controls at two weeks after treatment.

“Tea tree oil could be effective as a preventative treatment for wounds caused by mulesing, tail docking or any wound likely to be struck. It’s also been shown to have antibacterial properties and is suggested to have wound healing effects,” James said.

The composition of tea tree oil has been regulated under the International Organisation for Standardisation standard ISO 4730 (oil of Melaleuca-terpinen-4-ol type), and this recognised quality control helps to counter some of the criticism directed at natural pest controls not bound by the same regulations.

“The appealing aspect of using tea tree oil as an insecticide is that it’s a natural product. We’re seeing more consumer demand for the use of naturally sourced products in food and fibre supply chains, but the use of many natural products on a commercial scale has often been hampered by its variable quality. Tea tree oil is very well placed in this regard as its composition is specified under an international standard. This ensures the supply of a consistent product, which is essential when using a product as an insecticide.”

According to Dr James more research will be necessary to determine the exact formulation to make tea tree oil a viable treatment for fly strike and lice infestations. The process is: “an exact science, and not simply a matter of mixing tea tree oil with water and applying it to sheep”.

Anne Layton-Bennett

The research findings are available in the RIRDC publication: ‘Controlling fly strike and louse infections in sheep with tea tree oil’ available here.