The changing face of chemical treatments

Drench resistance is a common issue faced by farmers and there is a lot of awareness about it - there is less publicity regarding resistance in blowflies.

This is a significant and emerging issue in our country.  The change in weather patterns is resulting in increased fly issues especially in areas where fly is not traditionally a problem. 

The Australian Green Blowfly (AGB) is now the key species initiating most strikes, with sheep its preferred site for laying eggs.  Once the strike is started, the other fly species join in. Prior to the arrival of the AGB in the 1980’s, the European Green Blowfly was the main cause of strike.

In Australia, the AGB has high levels of resistance to organo-phosphates (OPs), especially diazinon. With the resistance to diazinon comes a cross resistance to another chemical, diflubenzuron.

It will be of no surprise that the New Zealand AGB shares the same genetics as the Australian GB and hence the same resistance characteristics.  OPs are no longer used but diflubenzuron is the chemical used in Fleecemaster, Zenith and Magnum. During 2006 – 2010, resistance to triflumuron (Zapp and Exit) also emerged in the North Island and resistance to this chemical is now widespread, affecting both the AGB as well as the European Green Blowfly.

Our product range, Cyrazin, Cyrazin KO, Cyroshield, Vetrazin, Cyrex, Strikeforce S, Clik and ClikZin  remain fully effective against all four of the flies that strike sheep.   These products act to break the fly cycle by preventing the fly larvae from moulting.

The more potent and longer acting products in this range are Strikeforce S, Clik and ClikZin.  These have the added advantage of being manufactured in ready to use, low volume formulations. A major benefit of these products is that usage is relatively fool proof (no dilution rates, no sump cleaning, no stripping of chemical from wash, no wash to dispose of) and the equipment used to apply is cheap and easy to use (either with a drench-type gun fitted with a spray/T bar nozzle or by using gas powered applicator “Power Doser”).

If you need more information on preventing flystrike in your flock, please talk with your vet or our specialised staff (Roy in Taumarunui, Carla in Feilding, Alby Pahiatua, and Amanda in Dannevirke).

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