How to control Buffalo Fly and avoid resistance

Buffalo fly is a serious problem for cattle producers in the north of Australia. Worryingly for the cattle industry, the problem is becoming more widespread, and producers in areas as far south as Dubbo in central NSW are facing their own Buffalo Fly battles. Buffalo fly and its resistance continue to have an economic and animal health impact on herds throughout Australia. Effective treatment is paramount in controlling the problem.

What is Buffalo Fly?

Buffalo fly is a small biting fly that lives permanently on host cattle, feeding up to 20 times per day by consuming cattle blood. Adult flies can live for 2-3 weeks and are continuously laying eggs before they die. Female flies can lay up to 360 eggs before they die, which allows this pest to rapidly grow in population numbers.

What makes the Buffalo fly dangerous is its blood-sucking characteristic. Flying from animal to animal, these parasites readily spread a host of diseases via the bloodstream. In addition to bacterial and viral diseases, Buffalo flies transmit a small parasitic worm that causes sores around the eyes, neck, and shoulders of cattle. This creates extreme aggravation to cattle, bringing infection that causes the animal to rapidly lose condition, including weight loss, lower milk production, and permanent hide damage.

The impact of Buffalo Fly on the Cattle Industry

A 2011 Meat & Livestock Australia report highlights that parasites, in particular the Buffalo Fly and its resistance, costs the northern Australia beef industry $20-30 million each year. In addition, animals having to deal with this parasite face a raft of welfare issues.

Buffalo fly infestations can vary from animal to animal. Bulls and dark-coated cattle, especially black cattle, seem to carry the largest fly burdens. Buffalo flies live permanently on their host, the females only leaving to lay eggs in freshly deposited dung pats. Some cattle are ‘allergic’ to buffalo flies and are intensely irritated by as few as 4 or 5 flies.

Animal welfare is an important consideration as cattle suffer constant irritation, painful bites causing distress, graze less, and are continuously rubbing to relieve irritation.

From a production perspective, cattle infested with Buffalo Fly are continuously fighting flies instead of grazing. If you have bulls in your herd, suppressed activity can also occur under heavy fly pressure.

Common buffalo fly effects include:

Reduced weight gain – a moderate infestation can cause average weight losses of 15kg over the fly season
Calf weight gain loss – with less milk being produced by adult cows infected by buffalo fly, the flow-on effect causes calves to also experience weight loss
Lesions – causes animal discomfort, and affects hide values for the producer
Pinkeye – another common condition suffered by cattle as a result of buffalo fly infestations
Resistance to current treatments

Controlling Buffalo Flies

The QLD Department of Agriculture and Fisheries recommends implementing a multi-pronged strategy to control buffalo flies.

Their strategy includes:

Non-chemical and chemical reduction techniques
Self-treatment using insecticidal ear tags

Flytrap tunnels and nature waste eliminators, dung beetles, can be effective non-chemical ways to reduce buffalo fly numbers. Chemicals however remain the most effective protection against buffalo flies, especially in high number infestations.

What are insecticidal cattle ear tags?

Insecticidal cattle ear tags are made of a moulded PVC that has been impregnated with a slow-release contact insecticide and are an excellent way to deal with buffalo fly. As soon as the tag is applied to the animal the insecticide commences releasing from the tag, with small volumes being released daily over a 3-4 month period.

Insecticide-impregnated plastic ear tags are the most widely used method of buffalo fly control in Australia. The tags slowly release chemicals over a defined period. Cattle grooming and interaction deposits chemicals from the tags onto the shoulder, back, and flanks of treated animals. Tags must be removed at the end of the payout period to avoid exposing flies to sub-lethal doses of chemicals.

There are three major active ingredients used in insecticidal ear tags:

Pyrethroid
Diazinon (organophosphate)
Abamectin (macrocyclic lactone).

Using cattle ear tags to control Buffalo Flies

As mentioned above, as soon as a tag is applied to an animal, it starts working. The active ingredient is transferred into the animal via their hair follicles, assisted by the natural grooming and contact habits within the herd. Due to the small dose released daily, the active ingredient is not absorbed into the meat or milk.

For the best outcome and to avoid resistance, every beast MUST be tagged in the herd with the recommended number of tags, either 1 or 2 tags per beast. Selective tagging does not work. Tags are always applied to the back of the animal’s ears, and tags must be removed immediately after the efficacy claim period (3-4 months) ends. It is important to refer to the directions of use supplied with your tags.

Where possible, synchronized tagging with your neighbours using the same tag and applying at the same time is highly recommended. Flies are not contained or restricted by fence lines; the more producers control together, the better the control becomes.

Different types of cattle buffalo fly ear tags

There are several types of insecticidal ear tags on the market, each targeting a variety of problems. Insecticidal ear tags come in a number of different sizes, strengths, and duration of protection. Some only need to be used as one tag per beast. Others require two.

Different ear tags use different active ingredients, and it is this active ingredient that must be looked at when working out which tag is best for your herd. What you also need to consider is the avoidance of buffalo fly resistance to the chemicals in ear tags; ideally, the active ingredient should be rotated annually to avoid buffalo fly resistance.

Managing Buffalo fly insecticide resistance.

Worldwide, insecticide resistance has been documented in more than 500 insect and mite species. Resistance in a pest population will develop quickly whenever all individuals in the population are intensively selected with continuous insecticide treatment for several generations.

For Buffalo fly, the rate of resistance development is dependent upon a complicated interaction among genetic, biological, and operational factors. As cattle producers, management practice can only influence operational factors.

Of greatest importance, to effectively manage the development of insecticide resistance in Buffalo fly is strict adherence to industry-advised rotation strategies. These strategies are designed to ensure that with each new season treatment is provided with an insecticide from a different mode of action with a different active ingredient.

In the case of ear tags, the rotation includes treatment with organophosphate, followed by synthetic pyrethroid, and finally treatment with macrocyclic lactone.

Of equal significance though, is a commitment by producers to follow the label recommendations and in particular to ensure that the insecticidal ear tag is removed at the conclusion of the treatment period, which is usually after 16 weeks.

Failure to carry out the practice of removing spent ear tags will have significant consequences for the onset of insecticide resistance. This is because at the conclusion of the control period ear tags continue to release insecticide but at a sub-lethal dose, placing extreme selection pressure on the inherent Buffalo fly population present at the time.

Therefore, integrating a control program will aid in slowing resistance development. To also aid in avoiding resistance in your herd It is strongly advised that you involve your neighbours in this discussion and work together where possible to follow a similar routine, as buffalo flies do not follow fence line rules.

The Y-Tex range of insecticidal cattle ear tags offers the only 3-way insecticidal chemistry rotation program available today. An outline of a suggested rotation program follows:

Year 1

Y-Tex Aggressor Tag (Abamectin – macrocyclic lactone). Two tags per beast are required. Offers up to 4 months of protection against Buffalo fly.

Year 2

Rotate to Y-Tex Warrior tag ( Diazinon and Chlorpyriphos). One tag per beast is required. Offers up to 3 months of protection against Buffalo Fly and cattle lice.

Y-Tex Optimiser tag (Diazinon – organophosphate) – two tags per beast are required. Offers up to 4 months of protection against Buffalo Fly.

Year 3

Rotate to the Cylence Ultra Insecticide Cattle Ear Tag (synergized pyrethroid) – 2 tags per beast for up to 4 months protection against Buffalo fly and cattle lice. Please note these tags cannot be used with the Y-Tex applicator but can be used with an Allflex UTT3S, Universal (Red) or LazaMatic applicator.