ARCHIVE FILE
This article was published in 1960
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Aspects of Cattle Tick Control
R. M. WATTS, B.V.Sc., Deputy Chief, Division of Animal Industry, N.S.W.
Before considering the many problems associated with the control of Cattle Tick on the Far North Coast of this State, perhaps it would be timely to give an outline of the area involved.
Cattle tick now exist over an area of 8,000 sq. miles of country, on which are depastured some three-quarters of a million head of cattle. For the sake of convenience in administration, the area is divided roughly into tick quarantine areas east of the Richmond Range, which include Kyogle, Tweed and Richmond; areas west of the Richmond Range, which embrace Woodenbong, Tabulam, Bonalbo, River tree, North Cheviot and Boonoo Boonoo; and finally the Grafton and Copmanhurst sections.
The number of men employed with the Board of Tick Control varies according to the programme being adopted, but at the present time the number is 600.
It is axiomatic in disease control that the movement of stock can be limited. To this end, the external perimeter of the tick quarantine areas is adequately fenced, and also the division between those areas east and west of the Richmond Range. On the Queensland Border and on the Richmond Range the fences consist of a main and buffer fence, whereas on the western perimeter and southern boundaries a single fence exists. It is of interest to note that in the tick quarantine areas there are 600 miles of single fence and 400 miles of double fence.
All boundaries adjoining 'clean' country are patrolled on a seven-day a week basis, while the Richmond Range fence is dealt with by a five-day week patrol. The maintenance of 1,400 miles of fencing presents quite a considerable task, especially as the fencing must be stockproof; and in order to cater for the damage caused by fires, storms and floods, the staff required as Patrol Officers and Gatekeepers totals 200.
All dips in the tick quarantine areas are erected by the Department on land either obtained from the Crown or leased from stockowners. In the section east of the Range there are just under 1,000 dips, west of the Range 225, in Grafton 160 and in Copmanhurst 100, a total of 1,450 dips. Of these, the dips in Kyogle and the areas west of the Richmond Range, and also in Copmanhurst, are in DDT, whereas the majority of dips in the Tweed, Richmond and Grafton areas are still in arsenic at the present time. Although the number of DDT dips is increasing, and will continue to do so to deal with arsenic-resistant ticks, there are approximately one-third of the dips in DDT.
It will be apparent from the foregoing that a control policy is an expensive item. Since 1926, £13,000,000 has been spent on control and eradication programmes, and the present rate of expenditure has been £1,000,000 per annum over the past two years. It has been estimated conservatively that the annual return from dairy products amounts to £5,000,000; a similar amount from beef cattle; whilst the pig industry has an annual turnover of £3,000,000.
A control policy does prevent any economic loss by the stockowner in respect of tick worry, loss of meat or milk production, and depreciation of the hides. Naturally the mustering and dipping of stock is an inconvenience to stockowners, but as the cost of control, including the provision of dips, is borne by the Department of Agriculture, the stockowners are in a much better position than in the northern States of Australia so far as cattle tick control is concerned.
If sufficient finance is available, a control programme consists of the following:—
East of the Richmond Range:
All dry stock and beef cattle are treated at monthly intervals for nine treatments, beginning in October and ending in June. Where an infestation is detected, the stock are given four treatments at fortnightly intervals, and this is repeated until the cattle tick are controlled.
West of the Richmond Range:
This is regarded as marginal country, where the infestations are much lighter than east of the Range; consequently the policy season extends for five months from January to the end of May, during which time all beef cattle and dry stock are treated at monthly intervals.
In both areas, milking stock may be examined or dipped, according to the owner's decision.
Copmanhurst follows a similar pattern to the West of the Range areas, whilst in the Grafton section the policy this year is one of examinations; dipping being confined to the known infested areas of Clarenza and Southgate.
Stock moving within the tick quarantine areas may do so on a clean examination and treatment; such movement being covered by Form 3 (that is, a Permit under the Stock Diseases Act).
There have been times, especially so since the completion of the eradication, when the finance has not been sufficient to implement the policy outlined above. When this happens, priority is given to those areas west of the Richmond Range and Grafton and Copmanhurst, whilst the Tweed, Richmond and Kyogle areas are obliged to accept a modified control in which dips are maintained by the Tick Staff but the stockowners do their own dipping.
The problems which concern the tick quarantine areas at the present time are:—
1. The prevention of spread of cattle tick to 'clean' country.
Stock moving to clean country are required to have at least three treatments at intervals of not less than three or more than seven days, and all treatments must be carried out in chlorinated hydrocarbon dips. Usually the first two treatments are in DDT and the final treatment must be in a DDT/BHC mixture. The last two treatments must be clean, which necessitate a close examination of the stock for any cattle tick prior to dipping.
It has been found that although stock may be completely submerged in the dip, or even when their heads are treated with a stirrup pump spray or wetted with a bucket of fluid, they may still have viable cattle tick inside the ears.
Whilst close inspections of stud stock and dairy cattle can be carried out, the ordinary run of beef cattle present certain problems insofar as their ears cannot be examined as closely as is desirable, and this is a cause of some concern.
2. Arsenic resistant ticks.
Arsenic resistant ticks first made their appearance in the Kyogle area in the Grady's Creek and Lynch's Creek sections in 1952. Since then there has been a gradual spread of arsenic resistant strains to the Tweed and Richmond areas, and as a result DDT dips have to be charged to deal with the infestations. A DDT dip is approximately twenty times as expensive to charge, and then to maintain, as an arsenical dip. In addition, the analytical procedure for chlorinated hydrocarbons is far more complex and time consuming than a straight arsenic estimation.
It will be realised therefore, that apart from the cost involved and the extra chemical work required, arsenic resistant ticks present an important problem. Furthermore, whilst arsenic is a true solution, the DDT formulation used is a suspension, and much more attention must be paid to the care and maintenance of a DDT dip than with arsenic. For instance, before stock are allowed to go through a DDT dip, the mixture must be stirred mechanically by the Tick Staff to incorporate the DDT that settles to the bottom of the dip into the dipping fluid. This process is carried out with a long-handled shovel and takes from a quarter to half an hour to do properly. Following the mechanical stirring a number of cattle, usually about ten or so, are put through the dip as "stirrers" to bring the dip up to its potential strength. These stirrers must be dipped again at the end of the mob.
The sampling of DDT dips for analysis also requires special care, and special apparatus has been evolved for this purpose. Whilst chemical analysis is a very important phase of the dipping activity, it cannot be left at that. It is also essential to see how much DDT is deposited on the hair and hides of the animals under varying conditions, to give an indication of the efficiency of the dip.
Various formulations deposit different amounts of DDT, and it has been the practice to limit the types of DDT dips to two in the tick quarantine areas, as experience has shown that many formulations do not give the required deposit.
3. Mechanical transmission of cattle tick.
Whilst the danger of the spread of cattle tick by cattle and horses is appreciated, the danger of mechanical transmission through such agencies as plants, grass seed, hay, straw and timber must not be lost sight of. Consequently, grass seed and hay are fumigated with carbon bisulphide; whilst plants are immersed in a 0.05 per cent. Diazinon solution.
There is also the possibility of mechanical transmission of cattle tick in the movement of vehicles associated with the transport of livestock; consequently motor lorries must be sprayed before moving into clean country. Mechanical transmission by humans is also a danger, but one that is very difficult to control.
4. The role of native fauna.
For some time at has been accepted that native fauna such as kangaroos, wallabies, bandicoots and bush rats did not play any significant role in the spread of cattle tick, but this is an aspect which requires further investigation. It is known from experiments that under certain conditions cattle tick can develop on rabbits and mice. Arrangements are now in band for research to be undertaken by the Wildlife Section of the C.S.I.R.O. to assess the possible role of native fauna in the spread of cattle tick.
5. Life cycle of the cattle tick.
From entomological work undertaken at Yeerongpilly it has been assessed that the life cycle of the cattle tick off the host is no longer than twelve months. In the eradication programme a dipping phase of fifteen months is enforced; the additional three months considered adequate to allow for any extension of the life cycle of the cattle tick.
It is now necessary to confirm the findings of the entomologists under the climatic conditions which prevail in the tick quarantine areas, and this work will be undertaken shortly with the establishment of the Cattle Tick Research Centre in the Lismore district.
6. Acaricides and Formulations
Whilst at the present time only arsenic resistance has been encountered in the tick quarantine areas, the position is different in Queensland where resistance to most of the chlorinated hydrocarbons has been demonstrated; such as BHC, Dieldrin, Toxaphene and in isolated areas, to DDT. Resistance to organic phosphates such as Diazinon and Asuntol has not yet been shown, but organic phosphates have not been included in the dipping fluids in this state as it is felt very desirable to have a further acaricide available to deal with any chlorinated hydrocarbon resistance which may occur in our tick areas.
The work so far undertaken with DDT indicates considerable variability in efficiency according to the formulation used. The "supercooled melt" types have been the most effective, and are the ones in use. On the other hand, on laboratory tests it would appear that a suspension of micronised particles of DDT powder would be the most efficient preparation, but on field tests it has shown on more than one occasion that this is not so.
The heating of DDT prior to incorporation in the dips is a process which presents certain difficulties, and if efficiency could be obtained with formulations without this pre-heating, a considerable advance would be made.
It can be stated that no matter what acaricide is used, more detailed work and thought must be given to types of formulations in which the tickicide is incorporated than in any other aspect of the acaricide.
7. Introduction of cattle tick from Queensland.
It is apparent that a very careful watch must be kept on the possible introduction of cattle infested with cattle tick from the northern States; especially as the degree of resistance in Queensland is far more widespread than here.
Dips on the N.S.W. - Queensland Border are charged with DDT. So far this has proved to be an effective dip to deal with any possible introduction of cattle tick. However, the position must be watched carefully, as it is possible for cattle infested with DDT resistant ticks to be presented at the Border.
8. Wetting of Cattle
It has been indicated earlier that thorough wetting of all portions of the body of the animals during dipping is difficult to obtain. This applies mainly to the head, and particularly to the ears.
In the research programme envisaged, work will be carried out on the mechanics of dipping to develop ways and means of ensuring that thorough wetting is achieved. This may mean a combination of dipping and spraying to ensure that all pass of the animal are saturated with the acaricide.
9. Tick Fever.
For many years Tick Fever was confined to the valley adjoining the Queensland Border in the Tweed area. However, the disease has appeared in many sections of the Richmond Quarantine Area, and even on the western side of Casino. Losses generally are not high due to the immediate action taken to control the outbreaks, but there have been isolated cases where the mortality has ranged from 10 per cent, and, in one instance up to 100 per cent.
As Tick Fever is one of the most serious diseases which can affect a susceptible cattle population, the position in the tick areas with any modified control policy, cannot be regarded with equanimity. The main functions of tick control are to keep the cattle tick within the present tick quarantine boundaries, and to prevent serious outbreaks of Tick Fever. This can be accomplished provided sufficient finance is available to put in a control programme as already described. Any departure from such a policy well could increase the risk of the spread of cattle tick, as well as allowing Tick Fever to spread.
A worthwhile control programme is a costly business and at least £1,000,000 per annum is required to implement control measures to keep the tick at bay. The question arises whether the insurance premium of £1,000,000 per annum is too high for the value of the industries involved, and this point is debated from time to time.
How far cattle tick will spread is a matter of conjecture, if they were allowed to come down the coast and even into Inland areas such as the Hunter River. It has been suggested that the tick may have reached the limit of its spread, but one feels that there are many areas, even on the South Coast of New South Wales, which are suitable for the propagation of cattle tick which could, in the appropriate season, reach significant proportions.
A cattle dip costs at least £1,500 to erect, and in an area where cattle ticks exist it is necessary to have these dips placed at distances of 11 miles for dairy cattle and 3 miles for beef cattle. Any spread of the tick, therefore, would be responsible for big capital expenditure if control were carried out by dipping - the only manner approved in this State.
It is unfortunate that the cattle tick eradication campaign which began in 1956 was not successful. It is a fact, however, that certain areas such as Cullendore, Cheviot and Bookookoorara have been cleansed, and there is every hope that Boonoo Boonoo and the Legume section of Woodenborg will be released this year.
In summing up, it may be said that the cattle tick problem in 1960 is even more serious than it was fifteen years ago. The area involved is larger, and the choice of acaricide is more limited. Futhermore, the cost of the control programme is now reaching a very high figure.