The two-year project by Massey University is developing a risk model for fly strike so farmers can more accurately know when it is likely.
School of Agriculture and Environment head Professor Paul Kenyon outlined the project at Limestone Downs Station’s annual open day near Port Waikato.
It will be similar to facial eczema risk assessment.
Similar fly strike risk models are already used in Britain and Australia.
Creating the model means collecting lots of information on climate conditions and populations of the two main fly species responsible for strike, Lucilia cuprina and Lucilia sericata.
Massey University graduate student Paul Brett is identifying the flies.
“Paul is collecting hundreds of flies each week, luckily he’s an entomologist because he likes flies and what he has to do is look down a microscope at every fly and he diagnoses the flies as the two types of strike flies based on how many hairs are on the head.
“You can imagine that’s an exciting job,” Kenyon said.
Flies are collected from traps on eight farms, including Limestone Downs, throughout New Zealand over two years.
Weather stations are set up on each farm to monitor maximum, minimum and average temperatures, humidity and wind direction. The farms also have three soil probes to monitor temperature because that affects fly emergence.
The meteorological data is then matched with the fly collection data.
Fly strike is caused by flies laying its eggs on sheep. The maggots eat the sheep’s living flesh and poison them with ammonia secretions. It affects sheep health and production, causing an on-farm financial impact.
“Sheep farmers rank fly strike as one of the biggest issues they have to deal with,” Kenyon said.
In the 2018-19 season across the eight sites the traps were out from September to May to determine when the season started and finished. The exercise has been repeated over the 2019-20 season.
The data collected shows the cuprina fly was trapped from October to May while the sericata fly was found from late November to April. At Limestone Downs the peak capture times were February 4 and late February for the sericata and cuprina fly respectively.
Once the data from this season is collated it will be tested using international models and a new local model to see which is more accurate.
To make it more user-friendly, the researchers will incorporate Niwa’s virtual climate stations into the model so farmers can use it to predict local risk times.
“Once we have got through this summer-autumn to work out when the end of the season is we’ll be at the stage of testing some of those models. Hopefully, in a couple of years we’ll have an accurate prediction model for fly strike, allowing farmers to make more informed decisions when they do the various management options on their farms to mitigate against it.”
