External
To minimise the chemical residues left behind from the control of external parasites, whilst simultaneously driving lice and blowfly incidences down, AWI provides Australian woolgrowers with guides to best practice. AWI is currently developing new diagnostic and treatment methods and is finding viable, humane mulesing alternatives.
Background
Better use of existing technologies
New products and practices
New diagnostic tests
Replacing/improving undesirable practices
Background
Lice are estimated to cost the Australian sheep industry $125m per year. This is less than the $169m estimate of 1995, no doubt due to a reduction in sheep numbers, but also the wide-spread use of off-shears pour-ons.
Blowflies are estimated to cost $280m per year, considerably more than the $161m estimate of 1995. These costs include mortalities and production losses (reduced wool cut, stained wool, cotts, lowered staple strength), as well as the direct costs of control (mainly jetting treatments and labour).
Control of lice relies on biosecurity - to prevent lice being introduced to the flock - and where an infestation is discovered, treatment with an effective lousicide. A number of tools are available to prevent and treat blowfly strike, including mulesing, tail docking, jetting with chemicals, fly traps, and breeding for fly-resistant sheep.
However, management of external parasites is threatened in a number of ways:
- Gradual development of resistance to chemicals by insects
- Possible restrictions on market access, in the European Union in particular, if wool contains pesticide residues
- Changing public expectations of animal welfare in regard to mulesing and associated procedures
- Increased scrutiny of the occupational health and safety implications of certain chemicals, notably diazinon
- Increased scrutiny of the on-farm environmental implications of sheep dips.
AWI is addressing these threats, and attempting to lower the cost of louse and fly control for wool producers, in four ways:
- Better use of existing technologies
- New products and practices
- New diagnostic tests
- Replacing/improving undesirable practices
Better use of existing technologies
Control of lice, flies and worms can be improved in many sheep flocks by applying principles of integrated parasite management (IPM). IPM means that a range of chemical and non-chemical methods are brought together to tackle the parasite problem.
AWI's flagship project in this area is the Integrated Parasite Management - sheep (IPM-s) project. IPM-s is a $2.6 million investment over the three years to 2007 to develop, apply and test IPM systems across a range wool production environments. There are 22 IPM-s demonstration farms across Australia. For further information, contact Charlie de Fegely.
Other key projects include:
- Development of a decision support model for lice control, which studies the spread of populations of lice and uses the data to construct a user-friendly model. The model aims to assist woolgrowers decide the best time to treat and what chemical should be used, taking into account pesticide residues.
- Development of a predictive model for blowfly strike. This project aims initially to determine whether extensive field data on fly numbers, weather conditions and strike - collected in previous studies - can provide accurate prediction of flywaves.
- Investigations into resistance by flies and lice to insect growth regulator (IGR) products, to determine how quickly it might spread and what other chemical groups might be affected.
New products and practices
It is important that there is a steady stream of new tools being developed for the control of lice and flies.
AWI has a number of projects in this area, including:
- The blowfly genome project aims to 'map' the blowfly genetic code. This will hopefully identify weak points that could be targeted by new insecticides, vaccines or other treatments. It may also provide useful information on the mechanism of resistance and how best to avoid it. This very basic research is still several years from producing commercial results.
- Two projects on biological control methods - one studying a fungus, the other a microscopic worm, both of which will attack and destroy blowflies and lice. Initial studies have yielded encouraging results, but much work needs to be done to reach the goal of a commercially viable product.
- Investigating the potential for a new class of louse and fly treatments based on a naturally-occurring protein which has not been targeted before. This is also basic research, several years away from commercial results.
New diagnostic tests
A priority for AWI is to develop a test for the detection of lice on sheep. Lice can be very difficult to detect by eye, especially when the population is low. As a result, many producers treat for lice even though lice are not present - as an 'insurance policy'. Surveys suggest that up to 80 per cent of flocks are treated annually despite only about 30 per cent having lice.
A lice detection test would benefit woolgrowers by saving the cost of treatment, reducing the residue load on the clip, and reducing the resistance pressure on the chemicals used. A further benefit would be the identification of sheep infested with too few lice to be identified at shearing, but sufficient to become a problem before the next shearing.
Replacing/improving undesirable practices
Mulesing is highly effective at reducing the incidence of breech flystrike in sheep. With changing community iews on animal welfare, it has become the subject of criticism by animal welfare groups.
In November 2004, farm leaders announced that mulesing would be phased out by 2010.
AWI is funding several projects that aim to develop alternatives to mulesing or to minimise the stress to lambs caused by mulesing and associated procedures. See futher information about alternatives to mulesing.
See also: internal parasites.
Resources
Contact
Dr Johann Schröder
Program Manager, Animal Health and Welfare
Tel: +61 2 8295 3100
Contact via email
Related websites
www.wormboss.com.au
Publications
Listen online
- WormBoss, Innovation Radio, 17 April 2005 (Windows media file 2Mb)
AWI grower networks
Find out about AWI's community-based network groups in each state.