Essential oils could be a future weapon in the battle against red mite in layers.
Speaking to delegates at the WPSA meeting in Southport, Merseyside, earlier this week, University of Newcastle researcher David George outlined promising results in the search for a natural treatment against the parasite.
Red mite is a widespread problem with one recent survey suggesting that 87% of units are infected and the estimated cost to the EU industry in terms of treatment and loss of production is €130m (£121m) every year.
"And there is the problem of resistance to what few products are left available for use," said Dr George.
One possible solution is the use of plant-derived essential oils, which is being investigated in a DEFRA-funded project (MITeHEN). The first stage was to screen many different of essential oils, such as lavender to narrow down the list.
"Screening identified two promising candidates, thyme and pennyroyal essential oils. And testing on hens has just been completed where birds were sprayed with the oil at 16 weeks of age and then every six weeks."
Results look promising and both were effective in controlling the mites, results are to be published shortly.
However, Dr George concentrated on a related study which addressed the potential concern that the essential oils would taint the eggs.
Eggs were analysed for certain compounds, as well as a sniff test by a panel. "We even immersed eggs for 24 hours in the treatment solution to ensure there was no taint."
Analysis in the laboratory found no traces of compounds in the eggs. "We were surprised as the equipment used to detect the compounds is very sensitive."
However, sniff tests did find taint with the pennyroyal with eggs having a foul smell. "This would have a negative effect on consumers, therefore, pennyroyal looks unsuitable as a natural treatment for red mite."
In contrast, there was no problem with the thyme oil. However, he added that further analysis was needed to look in further detail, including taste tests of cooked egg.
When questioned about practicalities of using essential oils, he admitted that their effect is shortlived being volatile compounds, and they were looking at ways of reapplying it.
"One option could be to incorporate the treatment into the ventilation system, a bit like a plug-in air freshener.
"This could prove useful in targeting mites in areas that a contact product could not."
Another benefit of essential oils is that they contain several active ingredients, so resistance is less likely than with synthetic products based on one active ingredient.
- The egg taint element of the project was funded by BEMB with support from a WPSA scholarship.