Thursday, April 14, 2011
Article in Farmers Weekly
More tick tricks
Denys Wells farms in the Alexandria district between Port Elizabeth and Port Alfred in the Eastern Cape. Ticks became a major problem for his pure and crossbred Angus cows in the early 1990s, when they developed resistance to synthetic pyrethroid products.“For about 14 years we used Triatix with great results. But then we began to notice resistance,” Denys recalls. “Fortunately, I’m not the kind of farmer who likes to chop and change products, so I could still use organophosphates, but that only worked for about 12 months.”Denys’ dip advisor suggested the “synergistic” option – combining synthetic pyrethroids with amidens. This worked for about 18 months. But soon blue ticks were everywhere and Denys started losing livestock to redwater and gall sickness. To make matters worse, there was a drought.
Designing a tick-control strategy
Help came in the form of Pierre van Niekerk, a parasite management researcher from Pretoria who was inviting farmers interested in tick research to contact him. “Pierre and his team visited my farms, harvested some ticks and found that the ticks had a resistance to all three groups of dip,” says Denys. “Pierre designed a custom tick-control strategy for me.”Pierre’s approach worked and Denys reckons the problem is now under control. “A planned strategy is the way forward for farmers who want to control external parasites,” he says. “Take the time to harvest ticks, have them analysed to determine resistance, and have an independent specialist advise you on a strategy, evaluate progress and adapt the strategy if necessary.”Pierre agrees. “When I started working with Denys, the ticks on his farm had an average resistance of over 90% to all the dips on the market. “When we last checked, the resistance had dropped to 30% to 50%. That’s really good news, because although Denys has an outstanding Angus stud, he was selling fewer animals because of the high tick count.”Denys’s basic mistake was dipping too often. “Now he produces ‘clean’ beef, and by using less dip, he’s also helping conserve the environment,” says Pierre.“His clients know exactly what diseases his animals can tolerate. They also know these cattle are good performers that have developed a natural resistance to ticks.”
What farmers need to know
“Farmers need to learn more about preventative measures and the strategic dipping procedures that will help their herds develop tick resistance,” adds Pierre. “The ideal would be to reduce the economic impact of ticks on an animal’s production by reducing their impact on its health, while cutting out labour, and conserving oxpeckers and useful insects.“It’s especially important for farmers to know the degree of ticks’ resistance to ascaricides on their ranch. You can only do this by using the scientific approach and regularly sending sample ticks to the Pesticide Resistance Testing Facility at the University of the Free State. The results will help you formulate a dipping programme that works on your farm.”With strategic integrated parasite management, where dip cycles are limited to between three and five a year, nothing is left to chance. “Everything is measured and tested so that we can design a plan to overcome problems with minimum dependence on chemicals,” says Pierre.
“This is much better than the old approach to tick control where the aim was simply to eliminate the parasites. That’s impossible as ticks have started building up resistance to chemicals, with major economic implications for farmers in terms of labour, cost of chemicals, waste, and time.”Pierre says the time has come when the consequences of poor tick control practices should result in legal action, as in the case of fires. “Speculators can introduce resistant ticks to a farm or bring in diseases never known to the area. The same problem occurs when a negligent neighbour’s tick-control programme breaks down.”Contact Pierre van Niekerk on 082 220 8386 or e-mail pierrevn@telkomsa.net. |fw
Causes of dipping failures
Parasite management expert Pierre van Niekerk says dipping can fail for a number of reasons:Failing to scientifically test the effectiveness of active ingredients used.Listening to biased advice that aims to sell a specific product rather than to control and break down tick resistance.Home mixtures that don’t work.Poor grazing management.Undue stress, which makes animals more susceptible to disease.Ticks appearing in new localities due to climate change.
Blue tick blues
Every engorged female blue tick seen with the naked eye represents 476 blue ticks on the same animal completing their life cycles. Thus 70 engorged females represent almost 10 000 blue ticks, an astronomical number of resistant ticks ready to multiply further.A single blue tick consumes almost 3mg of blood during its life-cycle. Researchers in Australia have found it has an agent in its saliva that suppresses the animal’s growth and grazing ability. Cattle infected by blue ticks can grow less than 400g per day, compared to healthy ones that can grow nearly 800g a day.
2010-09-27
Denys Wells farms in the Alexandria district between Port Elizabeth and Port Alfred in the Eastern Cape. Ticks became a major problem for his pure and crossbred Angus cows in the early 1990s, when they developed resistance to synthetic pyrethroid products.“For about 14 years we used Triatix with great results. But then we began to notice resistance,” Denys recalls. “Fortunately, I’m not the kind of farmer who likes to chop and change products, so I could still use organophosphates, but that only worked for about 12 months.”Denys’ dip advisor suggested the “synergistic” option – combining synthetic pyrethroids with amidens. This worked for about 18 months. But soon blue ticks were everywhere and Denys started losing livestock to redwater and gall sickness. To make matters worse, there was a drought.
Designing a tick-control strategy
Help came in the form of Pierre van Niekerk, a parasite management researcher from Pretoria who was inviting farmers interested in tick research to contact him. “Pierre and his team visited my farms, harvested some ticks and found that the ticks had a resistance to all three groups of dip,” says Denys. “Pierre designed a custom tick-control strategy for me.”Pierre’s approach worked and Denys reckons the problem is now under control. “A planned strategy is the way forward for farmers who want to control external parasites,” he says. “Take the time to harvest ticks, have them analysed to determine resistance, and have an independent specialist advise you on a strategy, evaluate progress and adapt the strategy if necessary.”Pierre agrees. “When I started working with Denys, the ticks on his farm had an average resistance of over 90% to all the dips on the market. “When we last checked, the resistance had dropped to 30% to 50%. That’s really good news, because although Denys has an outstanding Angus stud, he was selling fewer animals because of the high tick count.”Denys’s basic mistake was dipping too often. “Now he produces ‘clean’ beef, and by using less dip, he’s also helping conserve the environment,” says Pierre.“His clients know exactly what diseases his animals can tolerate. They also know these cattle are good performers that have developed a natural resistance to ticks.”
What farmers need to know
“Farmers need to learn more about preventative measures and the strategic dipping procedures that will help their herds develop tick resistance,” adds Pierre. “The ideal would be to reduce the economic impact of ticks on an animal’s production by reducing their impact on its health, while cutting out labour, and conserving oxpeckers and useful insects.“It’s especially important for farmers to know the degree of ticks’ resistance to ascaricides on their ranch. You can only do this by using the scientific approach and regularly sending sample ticks to the Pesticide Resistance Testing Facility at the University of the Free State. The results will help you formulate a dipping programme that works on your farm.”With strategic integrated parasite management, where dip cycles are limited to between three and five a year, nothing is left to chance. “Everything is measured and tested so that we can design a plan to overcome problems with minimum dependence on chemicals,” says Pierre.
“This is much better than the old approach to tick control where the aim was simply to eliminate the parasites. That’s impossible as ticks have started building up resistance to chemicals, with major economic implications for farmers in terms of labour, cost of chemicals, waste, and time.”Pierre says the time has come when the consequences of poor tick control practices should result in legal action, as in the case of fires. “Speculators can introduce resistant ticks to a farm or bring in diseases never known to the area. The same problem occurs when a negligent neighbour’s tick-control programme breaks down.”Contact Pierre van Niekerk on 082 220 8386 or e-mail pierrevn@telkomsa.net. |fw
Causes of dipping failures
Parasite management expert Pierre van Niekerk says dipping can fail for a number of reasons:Failing to scientifically test the effectiveness of active ingredients used.Listening to biased advice that aims to sell a specific product rather than to control and break down tick resistance.Home mixtures that don’t work.Poor grazing management.Undue stress, which makes animals more susceptible to disease.Ticks appearing in new localities due to climate change.
Blue tick blues
Every engorged female blue tick seen with the naked eye represents 476 blue ticks on the same animal completing their life cycles. Thus 70 engorged females represent almost 10 000 blue ticks, an astronomical number of resistant ticks ready to multiply further.A single blue tick consumes almost 3mg of blood during its life-cycle. Researchers in Australia have found it has an agent in its saliva that suppresses the animal’s growth and grazing ability. Cattle infected by blue ticks can grow less than 400g per day, compared to healthy ones that can grow nearly 800g a day.
2010-09-27
Sarcoptes scabiei
Morphology
1. Small roughly circular mites. Females about 500 microns in diameter, Gnathosoma visible above
2. Large number of triangular denticles on the dorsal of the idiosoma
3. Legs appear paired anteriorly and posteriorly. Anterior legs are visible from the dorsal side but the posterior legs cannot be seen
4. Females have suckers on long unjointed pedicles on legs I and II
5. In the male legs I and II and IV end in suckers and leg III in setae
Hosts
It is generally accepted that there is a single species with a wide range of hosts. Some list these as different varieties e.g. Sarcoptes scabiei var. bovis, Sarcoptes scabiei var. canis and other as separate species eg. S.bovis, S.canis, S.suis, S.equi.
Life cycle
The newly fertilized female burrows into the horny layer of the skin and goes no deeper. Within hours of beginning to burrow she lays eggs singly at a rate of 2 per day for about 2 months.
The eggs hatch after 2 days and the hexapod larvae either leave the burrow or remain in it and moult into nymphs. Larvae on the surface enter hair follicles and moult to protonymphs and form a new burrow.
The protonymphs moult into deutonymphs which may remain in old burrow or form a new one and subsequently moult. Adults mate on the surface and the male remains on the surface. After mating the female forms a permanent burrow.
The life cycle is complete in 10-14 days. Transmission probably takes place via the newly fertilized females, before they start burrowing and can move fairly rapidly.Geographic distributionSarcoptes scabiei is a cosmopolitan species. It is common on both animals and humans in South Africa.
Distribution on hosts·
Humans: Webs of the fingers, wrists, arms, insteps, genitals and buttocks· Dogs: Stomach, hock, root of tail, head, muzzle. Intense pruritus, red spots like flea bites, papulets, yellowish crusts, skin thickened·
Cattle: Flank, tail root, legs and neck·
Pigs: Behind and on ears, back, inner thighs, around the eyes. Hypersensitivity and pruritis.· Goats and hairy sheep: muzzle, abdomen and goats may die· Horses: head and neck·
Rabbits: starts on legs, spreads to nose where crusty protuberance develop and they may die.
Economic importance and diseases caused.
Itching, severe irritation and exudation and there is a forming of a thickened crust on the surface. There is also loss of hair and the skin thickens where infestations are severe.
Economic Period.
Infestations are usually seen towards the end of winter.
In addition, for the sake cat pet owners, mites on cats: The cat scabies mite is known as Notoedres cati and is similar to the S. scabies.
1. They are small (0,5mm), anus situated, dorsally and not terminally.
2. Dorsal surface without spines but has a scale-like pattern on integument.
3. Anterior pair of legs visibly and not dorsally, but not posterior pairs
4. Suckers on long stalks
Hosts
Cats, sometimes dogs and also man.
Life cycle and disease caused.
Burrows in the skin of the face and ears where it cause mange like legions. May spread over the head and along the back. Thickening of the skin, hair loss and grey in colour.
Tick Control on Cattle and Game: Scorpion Dip Apllicator for Cattle and Game
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