By Natasha Reading, B.Ag.Sc
The tick season is upon us once more, and as always, parasite management is about prevention rather than treatment. Once an animal is showing visible signs of parasitism, significant production loss has already occurred, so we want to get on the front foot and develop a proactive strategy. In this article, we’re looking at Cattle Tick – Rhipicephalus (Boophilus) microplus. In order to fine tune your control strategy, an understanding of the tick lifecycle and your different treatment options is extremely useful.
Cattle Tick Overview & Life Cycle
The Australian Cattle Tick (Rhipicephalus microplus) is an obligate parasite and needs to feed on its host’s (cattle) blood in order to reproduce. It prefers warm and wet environmental conditions and will be found to be most active in northern areas from September through to February. However, eggs can hatch as early as the end of July or start of August when seasonal conditions suit.
The diagram in Figure 1 shows the lifecycle of the cattle tick, including sketches of the different life stages.
In winter months, there are very few ticks on the cattle, but there are plenty of eggs on the ground/pasture waiting for the weather to warm up to hatch.
Once hatched, they develop and climb up the grass and wait for cattle to come along. When pastoral conditions are ideal, and grass is longer and lusher than usual, it is easier for tick larvae to attach by getting them closer to the body of the animal (a bigger target to jump onto, as opposed to just the legs).
Once the eggs have hatched and the respective larvae have attached to cattle, they then feed on the blood of those cattle as they grow and moult from larvae to nymphs to adults. As a result of tick feeding, cattle may become anaemic which can lead to loss of condition and sometimes death. Cattle can also be irritated and their hide may become damaged.
When feeding, ticks release their own toxin which can sometimes be infected with Babesia or Anaplasma, organisms which cause ‘Tick Fever’. Bos taurus breeds (e.g., Angus, Charolais and Hereford) are more susceptible to tick fever than Bos indicus breeds (e.g., Brahman). Calves exposed to these organisms between 3-9 months of age will develop immunity and production losses due to infection will be minimal. On the other hand, calves younger than 3 months and cattle that haven’t been previously exposed to Tick Fever organisms will need some sort of chemical protection.
The Tick Zone
Properties within the zone highlighted on the map above are probably always used to controlling ticks. However, if you are new to managing susceptible stock within this area, you will come across ticks on your property during the wet season.
For properties just outside the ‘tick zone’, it’s important to continually monitor your stock for the presence of ticks and extremely important to give a knockdown/short-acting quarantine treatment to any incoming cattle arriving from the tick zone. It may also be wise to routinely treat with a macrocyclic lactone (mectin) drench, as this will kill any ticks on cattle. This should be done so in a way that does not interfere with your worm treatment efficacy. While using mectin products for tick control, it is highly recommended to supplement your worm treatment with a different class of drench such as levamisole or one of the benzimidazoles (e.g., albendazole), in order to prevent internal parasites building resistance.
Chemical Treatment
There are many different products that can be used to kill and or control Cattle Tick, and resistance to certain active ingredients on and around your property is something that must be kept in mind when choosing the right treatment strategy for your cattle. You can check with local authorities for resistance status around your area, as well as submit ticks for resistance testing.
Macrocyclic Lactones (e.g., ivermectin, abamectin and moxidectin) will kill any ticks that are on your cattle at the time of treatment. As they have a knockdown mode of action you will see almost immediate results (within 2 days). These usually come in the form of a pour-on or injectable.
Insect Growth Regulators (e.g., fluazuron) will kill ticks on cattle during their moult from one life stage to another by preventing the growth of a new exoskeleton. These generally come in the form of a pour-on and will have persistent activity for some time after treatment (up to 12 weeks). Note that it may take 2-3 weeks for cattle to be visibly free from ticks after treatment with these chemicals.
Amitraz is an excellent knock down product for use when dipping cattle. Although as with most dipping and spray on chemicals, take appropriate safety measures when handling the chemical and treated cattle.
Synthetic Pyrethroids (e.g., flumethrin and deltamethrin) and Organophosphates (e.g., chlorfenvinphos) have all been used extensively in the control of cattle tick over the years and there is a great deal of resistance across most tick areas. These may still be useful in some areas, however, check with local resistance databases before relying solely on these chemical groups for tick control.
| Length of Protection | Chemicals | Effective Period | Treatment Interval | Chemvet Product |
| Short Acting | Pour-On Mectins Amitraz Dip Organophosphates Synthetic Pyrethroids | 18-21 days | 21 days | Vetmec Pour-On |
| Medium Acting | Injectable mectins | 28-30 days | 28 days | Vetmec Injection |
| Medium-Long Acting | Fluazuron | 42 days | 42 days | Vetmec Tickmaster & Vetmec Tickmaster Plus Ivermectin |
| Long Acting | Long acting injectable moxidectin | 56 days | 56 days | Vetmec LA (coming soon!) |
Always remember to follow dose rates, withholding periods and re-treatment intervals as specified on product labels.
Goal For Your Control Strategy
Treat early in the spring to prevent the summer surge in tick numbers.
Early in the season, the best thing to to is keep the initial tick population low, and beat the ‘spring rise’ (see Figure 4, below) by applying a medium-long or long acting product just as eggs start hatching in August/September. Doing so means that larvae and nymphs are killed before they become adults and begin to reproduce, thus resulting in fewer ticks in the 2nd and 3rd generations. Which, without an early treatment will give rise to a summer surge of ticks on your cattle.
Another method may include treating with a series of shorter acting “knockdown” products once tick numbers reach your treatment threshold. For example, treating with a short-acting product every 3 weeks once you start seeing ticks. This is more of a reactive strategy and is most useful when the ticks on your cattle are already in their adult stage, and Insect Growth Regulators will no longer be effective as the ticks have already been through all their phases of moulting.
During the peak of the season (November – January), monitor your cattle to be sure that your treatment option has been effective, and re-treat with an appropriate product. Noting that resistance to long acting products may not necessarily mean the product is ineffective, but rather can be seen as a reduced protection period.
Come Autumn, although the number of ticks on the cattle may be declining, it’s important to treat once more in order to reduce the number of eggs that are dropped onto the pasture for next season, also known as reducing ‘pasture contamination’. This can be done with a medium to long-acting product with a protection period that takes you through to cooler weather, or a couple of short acting treatments.
Non-Chemical Management Strategies
Genetics
Introduce more Bos indicus genetics into your stock, e.g., Brahman, as these cattle develop a better natural immunity to Tick Fever.
Grazing Management
Paddock ‘sweeping’ involves putting young steers or heifers, under the protection of a longer acting treatment, into a paddock which is highly contaminated by ticks, and then moving the cattle onto a different pasture having swept up and killed majority of the ticks in the original paddock. This paddock could then be considered a low-risk pasture and more suitable for cows and calves.
Although spelling pasture is not always possible, it can be a great way to control ticks left in the environment, as immature ticks cannot survive off the cattle forever. However, the length of time required to spell a pasture differs depending on the season; as a general rule, 3 months during summer and 5 months during winter will greatly assist in tick control.
Calf Management
If possible, calve when ticks are inactive, as newborn calves are at a higher risk of serious illness or death from tick feeding. As they are smaller and have not developed any immunity yet, they require fewer ticks (and a smaller dose of Tick Fever organisms) to cause serious harm.
Vaccinate calves when they are 3-9 months of age, in order to expose them to a non-harmful version of the Tick Fever organisms and promote development of their own immunity in readiness for ‘real exposure’.
Summary
- Treat early to prevent build up of ticks on your property.
- Monitor and treat appropriately throughout the peak of the season.
- Utilise non-chemical strategies to reduce the frequency of chemical treatments.
- Treat in Autumn to reduce pasture contamination for next season.
- ALWAYS give a quarantine tick treatment to cattle coming from the tick zone.
Please feel free to get in touch if you wish to discuss any of the points outlined above.
Other Tick Species
This article is about management, treatment and control of Cattle Ticks. For information regarding Bush Ticks and Paralysis Ticks, www.tickboss.com.au/cattle is a great place to start.