SHEEP producers struggling with high levels of resistance to lice chemicals have been thrown a lifeline with a new, but expensive, treatment released last week.
The back-line lousicide, Avenge, from Bayer, costs about $1.10-$1.20 a sheep, or more than double current lice treatments.
But, despite the cost, Avenge is expected to be a welcome treatment in the fight against lice, which, according to authorities, infest more than 50 per cent of sheep in Victoria.
Much of the blame for this high incidence has been pointed to the removal of diazinon in plunge dips and increasing resistance to many of the proprietary back-line treatments using Insect Growth Regulators chemicals.
Diazinon, which is the only treatment to defy resistance, was removed from sale following occupational health and safety concerns.
However, it can used under permit in approved cage-dipping treatments.
Greg Richards, of Cavendish, who runs Dynamic Dipping, is the only contractor to date with a permit to use diazinon.
Mr Richards operates three dipping machines and said he was "being run off his feet in meeting the demand".
"We have orders to treat 330,000 sheep between now and January," he said.
Mr Richards said the lice problem, which affected wool quality and sheep productivity, was at epidemic proportions.
"I blame many of chemical companies for not pulling product off the market once it had developed resistance," he said.
To treat sheep, Mr Richards said he charged 55c, plus chemical, per head off-shears.
Bayer national brand manager Dave Ross said he was optimistic that Avenge wouldn't run into the same resistance problems as current back-liners.
He said this was because Avenge was classified as a "knockdown" treatment that acted within hours of treatment on the insect's nervous system, unlike the IGRs which could take days to produce a control.
In trials on 12 flocks, including two in Victoria, Avenge achieved such a good result that after six months there had been a 100 per cent kill, Mr Ross said.
Avenge comes with some strict label instructions.
Sheep should not be treated more than 24 hours after shearing.
Unshorn lambs or lambs weighing less than 12.5kg should not be treated and there is a nine-week withholding period for slaughter for export.
