Denys Well: Blue Tick Resistance Study, Eastern Cape

Background

The Wells Angus stud to have a resistance factor of 92% to 3 important acaricides. Organophosphates, amidine and pyrethroids and or combinations of the groups. With a higher dose of the groups, 72% of the female ticks survive the Shaw Larval Tests.

Resistance tests done by the Pesticide Testing Facility of Me Ellie van Dalen at the University of Free State.

The Wells Angus stud is one of the oldest studs in South Africa and a very well managed stud with the very best of Angus genetics in South Africa. Denys, by his own admittance, could not find at the time anyone, any Animal Health Company nor a vet in South Africa able to assist him to overcome his blue tick resistance challenge.

He replied to an add I had put in Landbouweekblad, asking for farms and studs with severe tick resistance to acaricides. He became one of 12 farmers across South Africa for the study.

Wells dipping profile

1. Denys is a well-disciplined breeder. Neat, precise and he developed a resistance problem because of his well-disciplined program and correct dipping procedures.
2. His dipping program was on average every two weeks. This calculates to approximately 25- 30 dip sessions per year.
3. Denys later with the increased development of resistant ticks, had to dip on occasions every week.

 The Pesticide Testing Facility results

Blue ticks were resistant to almost all acaricides, as mentioned above

• Part of the solution to his tick challenges was not to expose blue ticks to the chemicals and or combinations they prove to select themselves resistant to.
• The results indicate what chemical groups was excluded and what groups could be used.
• A product was selected. Blue ticks reacted to the chemical and almost 100% , eye visibility, was reached within 14 days.
• Multi-host ticks were then controlled with a “Pour on “pyrethroid as there is yet no prove or indications that they have selected themselves resistant to the acaricides.

Marker animals

Being far away from the farm, it was important to have marker animals. Marker animals will show early signs of tick infestation. Marker animals should be tagged and marked clearly and watched closely, as these animals will indicate the end of the products used efficacy and, predict a time period for forth coming infestations.

When marker animals show signs of tick infestation, the breeder will then have a clear indication on a possible time frame to plan a follow op dip sequence

Study outcome

1. Part of the study outcome was to minimize dip sessions to the very minimum.
2. Limit blue ticks to the very minimum in the exposure to acaricides and chemicals
3. Saving the following costs

• Costs to acaricides
• Time
• Costs to labour
• Wastage of expensive chemicals
• Exposure to chemicals
• Stress occurred during dip sessions

Marker animals was also an indication of the severity of tick infestations in camps grazed.

Multi-host ticks

Dipping sequence

As a rule of thumb, we collectively decided when approximately 10 multi hosts are visible with the naked eye, a next dipping session should be scheduled to control multi-hosts alone, within the parameters of predicted efficacy of the products used to control blue ticks.

Important: It was important to ensure that blue tick species were prevented to be unnecessary exposed to the chemicals they test resistant to.

Blue tick dipping sequence

1. The 1^st and 2^nd dip with different products was scheduled to be 14-16 apart. The only ticks predicted to be seen after the 1^st dip was multi-host species, as the product used was registered for the control of blue ticks only.
2. The product used 1^st proved to have a reasonable effect on two-host ticks as well, as none was found on the group of 50 animals.
3. The control group in the same camp on the same grazing patch, was though heavily infected.

Believe in the program

At first Denys did not believe the dip period prediction off the 2^nd dip. He thought the study was putting his stud at risk. In his 20 years being the owner of his dad’s farm, and in his dad’s time being the owner of this Angus stud, a period longer than 2 weeks of not dipping never occurred.

He did in the end, with a lot of scepticism, allowed the original 50 animals to be part of the study. Only after I had to take full responsibility for any tick related losses and said he will move back to his old program if he found the prediction false at any period of time.

The 2^nd Dip outcome

The prediction was no blue tick for the following 12-14 weeks, after the 2^nd dip.

A follow-up dip sequence would be scheduled after that period, after an inspection was carried out to see what was the level of infestation. That level would indicate when a new dip sequence would be scheduled.

In progress study challenges

Denys changed his mind after a period of 4 weeks and decided that his whole herd must be put on the study program. He was not interested in providing a group of animals, keeping it on his old dipping regime. He had enough of dipping, ticks, labour costs and the risk of tick related illnesses.

Outcome

1. During October 2007, ending October 2008, the following dip sequences took place
2. 1^st dip on October the 7^th 2007- Blue ticks
3. 2^nd dip 14 days later, October 22^nd, 2007 – Blue ticks
4. 3^rd dip December 15^th 2007, Blue ticks
5. 4^th dip April 3^rd 2008 Blue ticks
6. 5^th dip, August 17^th, 2008, starting with the first product and 14 days later, the second product on 6^th of September

Inspection was held in November. No ticks were to be found on the original group or the synchronised rest of the stud.

Inspection was held in February 2009. No ticks were found.

A multi-host preventative dip program was though proposed as certain camps against the mountains where heart water ridden. Only the animals in those camps have been dipped preventatively, 25 days’ dip intervals. They were not part of the original group in the study.

Resistance testing

A follow up was done on the original group. Only 55 engorged female ticks cold be harvested on the whole group of 50 animals in April of 2009. The resistance to acaricides dropped to the abovementioned acaricides to a level of 16%.

Dip sequence

1. A dip sequence of three strategic blue tick dip sequences was implemented since that period
2. Multi-host have two strategic and or preventative dip sequences. Early spring and approximately December 15 to prevent 3-host ticks such as brown ear ticks to flourish in their high seasonal occurrence and numbers
3. Mid-January, end of February and mid- to end of March.
4. In late wet seasons a dip session is also scheduled in April
5. Multi host ticks was not specifically targeted but became an important matter to deal with.

Pierre van Niekerk ©

pierre@dieregesondheid.co.za