Economic modelling has found cattle tick, Rhipicephalus (Boophilus) microplus, to be the most significant endemic cattle disease in Australia1. This note outlines some important cattle tick management principles for South East (SE) Queensland. Not all of these recommendations will seem practical for hobby farms but they form the basis for best practice in any enterprise struggling to control the parasite.
NSW maintains freedom from cattle tick by border and post-border surveillance activities and implements eradication programs for any identified tick incursions. Cattle tick is a notifiable pest under schedule one of the NSW Biosecurity Regulation 2017. NSW producers must notify an authorised biosecurity officer with NSW Local Land Services or NSW DPI if they suspect cattle tick. Whenever cattle tick are found in NSW, movement restrictions will be placed on the property where they are found and adjoining holdings to control the risk of further spread.
Without these regulatory activities, cattle tick could spread through much of eastern NSW, costing the NSW cattle industry an estimated $30 million annually.2
Cattle ticks are single host ticks spending on average 21 days on the animal and up to a year in environmental stages in the paddock. A single female tick can lay approximately 3000 eggs. To control ticks paddock contamination needs to be reduced, as well as clearing the animal. Repeated strategic treatments of animals in spring aims to beat the rise in tick numbers in paddocks. The spring treatment aims to cover multiple cattle tick life cycles, ideally achieving over 100 days tick suppression that covers four to five tick cycles of 21 days on the animal. This treatment is needed to have any real impact on egg contamination of paddocks. It will control cattle tick numbers on animals to help prevent production loss and welfare problems but will not eradicate ticks.
Suppressive spring adulticide treatment options include use of a spray or dip once every 21 days for four to five treatments, a pour-on macrocyclic lactone (mectin) once every 21 days for four to five treatments, a short-acting mectin injection once every 28 days for three to four treatments, or a long-acting mectin injection for one to two treatments fifty-six days apart. An insect growth regulator such as fluazuron can be used after the adulticide suppression treatment to complete a spring-summer program and introduce a different class of chemical. Research has identified that improved tick control occurs if fluazuron is administered after a long acting mectin adulticide rather than before3. A single adulticide treatment in autumn may be needed after a spring program before tick numbers naturally decline in winter.
Attention is needed to chemical resistance status and testing is available in QLD. Synthetic pyrethroids and organophosphates have high levels of resistance. Amitraz also has resistance but remains a useful chemical as one of the only true 'clearance' options. Its use should be combined with mectins to manage resistance. A mectin is given before amitraz is used because otherwise the amitraz (even if with resistant ticks) will make the ticks sleepy and they will not take in enough mectin from a blood feed to be effective. Fluazuron resistance is increasingly seen in QLD and can be suspected by a shortened protection period. Fluazuron use should also be combined into a program that incorporates a mectin to reduce the development of resistance.
Producers need to ensure that they follow label advice on Withholding Period and Export Slaughter Interval of all products used.
A good tick program is essential for health, welfare and productivity of cattle. However many cattle producers in the endemic tick areas of southern Queensland have a hit and miss approach, treating once or twice when they see ticks and this method has very limited impact. Testing chemical resistance status and seeking advice to design a strategic program is recommended.
Advisors should bear in mind that if a cattle tick program is very suppressive producers should be using the Tick Fever vaccine (Wacol) because if paddocks are cleaned up substantially of tick, cattle may not gain natural immunity to Babesia or Anaplasma. It is recommended best practice for all producers in South East Queensland to use the Tick Fever vaccine.
No resistance in Australian cattle tick populations has been identified to mectins but anecdotal reports have suggested reduced protection periods on some properties. Consistent with parasitology principles for other pests, it will become increasingly important in Australia to design cattle tick control programs that incorporate chemicals with different mechanisms of action and also non-chemical methods of control to reduce the development of resistance. Some properties have reduced overall chemical usage by paddock rotations and reserving suppressive programs for young growing stock that 'clean' the paddocks for later grazing by cow and calf units.
Veterinarians can play a key role in providing advice on strategic and sustainable cattle tick programs for cattle producers.