The tiny parasite that costs the northern cattle business almost $100 million a year in lost production is headed south, aided by climate change.
The more susceptible Bos taurus breeds and lack of routine parasite treatments in southern management systems is expected to fast track the invasion at a far quicker rate that its spread in the north.
Indeed, modelling has the potential spread of this livestock pest right down the Eastern Seaboard, into South Australia and also across to the south-west of Western Australia by 2030.
It’s definitely time southern cattle producers familiarised themselves with the buffalo fly.
Forewarned is forearmed, says Dr Peter James, senior researcher at the University of Queensland’s Alliance for Agriculture and Food Innovation and one of the country’s leading experts on livestock parasites.
Buffalo flies are on track to become a significant pest in southern beef and dairy industries as the climate warms and the pattern of expansion suggests new control measures be looked into, such as area-wide approaches and regulation, he said.
Speaking at the 2018 Australian Society of Animal Production conference in Wagga Wagga, NSW, Dr James said while cattle producers in the south were quite aware of tick issues in the north, their response to buffalo fly was often “what’s that?”.
Buffalo flies are small, 4 to 5mm is size, nondescript grey flies which are obligate blood-feeding parasites.
They spend most of their lives on cattle. The only time they leave the animal is to lay their eggs in dung and infestations can reach many thousands per head.
They bite up to 40 times a day and are highly irritating to cattle, causing lesions – particularly characteristic are those around the eye, Dr James said.
“They are the second most costly disease in northern Australian cattle after ticks,” he said.
“The big production losses are in growth rates (between 8 and 15 per cent), in milk output (up to half a litre per day) and in devalued hides.”
The parasite was likely introduced to Australia on buffalos from Timor coming into Darwin in the 1800s but it didn’t make it to the Queensland border until the late 1930s.
A couple of wet years in the early 1940s saw it jump across to the York Peninsula and by the mid 1940s it had reached Bundaberg.
“They sat there until 1974 when a further southerly spread again corresponded with wet years and a change in tick regulation,” Dr James said.
When Amitraz was bought in to treat ticks, this this did not have an effect on flies and it spread quickly – by the early 1980s it was on the Mid North Coast of NSW.
Wet years in 2010 and 11 sent the flies to Bourke, Dubbo and Narromine and it is now as far south as Maitland.
“We have tick treatments in the north which have interfered with the spread of buffalo fly but these aren’t part of management practices in the south so we now expect conditions will be suitable for persistent populations in SA and WA within 12 years,” Dr James said.
One factor which might facilitate an even faster southern invasion is the genetic plasticity of the species.
Buffalo fly is very closely related to the horn fly of the northern hemisphere, which has an ability to overwinter in the cattle dung, Dr James explained.
“Buffalo fly can’t do this but we believe that it has overwintered in low numbers on susceptible cattle in areas protected from frosts and this could assist the southern spread further.
“There is an opportunity to do something about it at the moment.”
Buffalo fly is currently a notifiable disease in SA and Victoria.
“Taking care not to transport any buffalo fly-infested cattle onto your property and spraying out new infestations as they occur might slow further spread,” Dr James said.
Source: The Australian Dairy Farmer