Summary
This paper provides a general overview of the functions of the National Registration Authority for Agricultural and Veterinary Chemicals (NRA) and its role in regulating agricultural and veterinary chemical products in the marketplace. It is one of four NRA papers to be presented at the FLICS conference and is designed to provide background information to the more focussed papers.

Summary
Before agricultural and veterinary chemical products can be sold, supplied, distributed or used in Australia, they must be registered and their labels approved by the NRA. A separate approval is also required for active constituents either before, or at the same time as a product is registered. This paper will describe the assessment process for registration and approval of a chemical product and will cover such aspects as the legislative criteria that must be satisfied, the advice the NRA may seek from external agencies as well as the consultation process with stakeholders. The paper will also outline the NRA information services available to assist applicants when preparing their application.

For an overview of the NRA please refer to the FLICS paper titled "The NRA’s Role in the Regulation of Sheep Ectoparasiticides".

Summary
Studies in L. cuprina and D. melanogaster have demonstrated that it is possible to generate single gene resistant variants in the laboratory using a combination of mutagenesis, to increase the variation available, and selection, above the LC₁₀₀ of susceptibles, to specifically screen that variation.

The data from L. cuprina are predictive of the results observed for naturally occurring field resistance to dieldrin and diazinon. This gives us confidence that the results gained for cyromazine are robust. The availability of data before an insecticide is used allows comparisons to be made between competing products. These data also inform decisions as to which concentrations and delivery systems should be used to minimise the evolution of resistance and to maximise the probability of effective control.

In this context the timing of when insecticides are used can be considered not just as a reactive measure in response to a fly wave but as a potentially proactive measure to have significant impact on the population dynamics of the blowfly at a time when it is ecologically vulnerable.

Summary
The Australian sheep blowfly (Lucilia cuprina) and the sheep body louse (Bovicola ovis) have both demonstrated their propensity to develop resistance to insecticides used for their control. Most populations of L. cuprina contain individuals resistant to organochlorines and organophosphates. Some are also resistant to benzoylphenyl ureas. Many populations of B. ovis are resistant to pyrethroid insecticides. However, very few populations are resistant to organophosphates. Treatments directed at lice infestations have selected for resistance in sheep blowfly so insecticide treatments need to be considerate of the possible impact on non-target parasite resistance. Flock management plans would assist in identifying options for producers but clearer information on pesticide residue/environmental requirements are needed first.

Organophosphate resistance in sheep blowfly is almost universal. These insecticides are of limited use against this pest even as flystrike dressings. Organophosphates can still be effective lousicides but application (plunge or shower dipping) to short wool sheep is extremely difficult and often fails to eradicate an infestation. Further work is needed to improve wet dipping and simplify maintenance of dip concentration. The future of these products is unknown as they are subject to regulatory review on environmental and safety grounds but currently they are very valuable to the wool industry.

There are still effective products available for sheep blowfly and lice control. Flystrike prevention is heavily reliant on cyromazine and lice control reliant on triflumuron and diazinon. Spinosad is a long wool option, should follow up, or late season treatments for either parasite be needed. Resistance to any of these compounds would seriously jeopardise producers' ability to control flystrike and lice infestations. Consequently, field surveys and cross resistance studies to determine baseline population responses to potentially new compounds remain necessary to responsible pest control decision making.

Summary
Studies of the prevalence of lice in Australian flocks and the cost of lice to the sheep industry are reviewed. Cost estimates updated to take account of changes in sheep numbers, wool prices, louse prevalence and the cpi index, indicate that lice currently cost the Australian sheep industry between $100m and $150m annually. The contribution of lice treatments to the total wool residue load in the 1999/2000 season is estimated at 63%. The importance of availability of an effective offshears backline product to keeping louse prevalence low and the effect of producers changing from routine annual treatment to treatment on detection for lice control is discussed. It is concluded that unless significant improvements are made in the efficiency of louse control programs a change from annual treatment to treatment on detection is likely to result in increased industry prevalence of lice.

Summary
Sheep were treated off shears in southern Queensland with a backline formulation of a benzoylurea insect growth regulator by a commercial wool grower. ‘Band’ samples taken from around the girth of two sheep were collected at shearing 12 months later and broken into backline, upper side, lower side and belly segments. Pesticide was determined at tip, base and mid staple on each segment to determine the extent of migration of the active agent away from the application site. Most of the residual pesticide on the sheep was found on the tip of the staple on the backline. There was little migration down the staple, or around the body of the sheep. Implications of the findings will be discussed.

Summary
Currently producers do not make any special arrangements for the disposal of spent dip wash at the end of dipping. Similarly, mobile plunge dippers currently have no easy means of either transporting or disposing of spent dip wash. It is thought that simply pouring the solution onto the ground without some form of containment is likely to be unacceptable to environmental bodies or to the community at large. We measured diazinon residues in soil following disposal of 4000 L of spent dip wash containing approximately 70 mg diazinon/L and a much lesser volume of sludge from the bottom of a mobile plunge dip containing 320 mg diazinon/L. Residues in soil across a 450 m ² disposal site were less than 10 mg/kg at 7 days after application.

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