Chemical Groups and Actives for Cattle

There are currently five chemical groups available for treating ticks on cattle in Australia. Click below to go directly to each group:

1. Macrocytic Lactones
2. Synthetic pyrethroids and pyrethrins (SP)
3. Organophosphates (OP)
4. Insect Growth Regulators (IGRs)
5. Amitraz

Macrocyclic lactones (ML)

What do they treat?

Roundworm, Flies, Ticks, Lice, Mites

Warning: When using MLs to target a particular parasite, be aware that they will also treat any other of the parasites mentioned above that are present. You can increase the development of chemical resistance by all of these parasites each time you use an ML product.

Note: Can kill dung beetles

How can they be administered?

A variety of application methods for administering pesticide products to cattle are in use.

Oral Pour-on Injection

• Pour-on formulations have greater variability in absorption than oral or injection formulations.
• Regardless of how they are administered effective levels of MLs will reach the gastro-intestinal system, lungs, and skin.
• Note when applied via oral or injection, MLs are not effective against biting lice.

Resistance

Reported in: Worms Ticks (found overseas, so far not in Australia)

What is resistance?

Safety

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

• Generally, MLs have a wide margin of safety to mammals.

Withholding

Withholding periods are mandatory with all registered veterinary products used to treat animals for internal and external parasites.

• Always check the product label before use for specific withholding periods (WHP) and export slaughter interval (ESI) periods. Current ESI periods can be confirmed on the APVMA website.

Types of macrocyclic lactone

A guide to the different actives and the pests they affect are in Table 1. See the Products Search for the appropriate formulation and application method for your target pest. Note that combinations and mixtures of actives may improve treatment efficacy.

Table 1. Macrocyclic lactones, their actives, combinations and mixtures and a summary of the targeted parasites for which formulations are registered for. Boxed check marks indicate the pest targeted by multiple actives.

Chemical	Pests targeted (may vary with formulation)
	Worms			Flies		Cattle tick	Lice	Mites
	Round worm	Intestinal tapeworm	Liver fluke	Buffalo fly	Stable fly
MLs
Ivermectin	√			√	√	√	√	√
Abamectin	√			√	√	√	√
Doramectin	√			√		√	√	√
Eprinomectin	√			√	√	√	√	√
Moxidectin	√			√	√	√	√	√
Combination (all actives target boxed parasite)
Abamectin and levamisol	√			√		√	√
Ivermectin and fluazuron	√			√		√	√	√
Moxidectin and levamisole	√
Abamectin, levamisole and oxfendazole	√	√
Mixtures (multiple targets)
Macrocyclic lactone and triclabendazole	√		√	√		√	√
Ivermectin and clorsulon	√		√			√	√	√
Mixtures and combinations (multiple targets, primary target of actives boxed)
Ivermectin, nitroxinil and clorsulon	√		√			√	√	√

What are they?

Macrocyclic lactones are products or chemical derivatives of soil microorganisms belonging to the genus Streptomyces.

How do they work?

MLs have a potent, broad antiparasitic spectrum at low dose levels.

MLs are fast-acting compounds that block nerve transmission in many parasites but have little effect in mammals. They bind to glutamate-gated chloride channel receptors in nerve cells. The resultant sustained channel opening allows influx of chloride ions and paralysis of the parasite neuromuscular system. This reduces the motor capacity of nematodes and causes paralysis, eventually resulting in de-attachment and expulsion from the animal.

MLs become extensively distributed throughout the body and concentrate particularly in fatty tissue. The route of administration and formulation may affect drug absorption, distribution, metabolism, and excretion.

Chemical mixtures and combinations

Multi-active products contain more than one parasitic chemical active responsible for killing parasites. The active ingredients within a multi-active product may target the same, or different parasites.

Multi-active products can be separated into:

• Mixtures of different actives that work against multiple parasite groups (e.g. liver fluke and roundworm).
• Combinations of different actives that target a single parasite.
• Both a combination and a mixture that target multiple parasite groups and have more than one active against at least one of the parasites.

Multi-active products or chemical mixtures and combinations have higher efficacy than the individual ingredients, and are effective against more than one type of parasite. The benefits of combining actives are:

1. Better results against parasites can be expected, as parasites resistant to one of the components are likely to be killed by the other components, or their combined effect.
2. The rate of development of resistance is reduced, as very few parasites are likely to be simultaneously resistant to all components.
3. Reduces labour by combining multiple treatments into one (i.e. when it is beneficial to treat cattle against multiple types of parasite at the one time).

Do not mix different actives together unless the label states you can, or under veterinary advice, as different products may be incompatible. Proprietary ready-made products have been tested to ensure the actives are compatible with each other and achieve the desired combination or mixture effect.

Mixtures

A mixture contains two or more active ingredients that target different parasite groups (e.g. roundworms and flukes). Mixtures have the convenience of a single treatment when quite different parasites are targeted; however, they should be considered ‘single-active’ against each parasite.

The mixtures available for use in cattle are mainly to treat round worms and fluke with one treatment.

Mixtures available for this purpose are listed in Table 1 below.

Your choice of mixture should be guided by which parasite you most need to control, i.e. whether liver fluke or roundworm is causing your greatest economic loss. Note that product mixtures and combinations containing macrocyclic lactones will affect both internal and external parasites, depending on the formulation and application method. To prevent increased selection for resistance in non-target parasites consider other parasites when choosing a product.

Combination treatments

A combination treatment has more than one active ingredient to target the same parasite. It offers more than one way to kill the parasite—the number of different ways is determined by the number of actives from different chemical groups included in the combination treatment.

Available combination treatments are listed in Table 1 below.

The benefit of including more than one active in a product is that the chance of a parasite being resistant to all active ingredients in the combination is much lower than for each individual active on its own. Therefore combination treatments are more likely to be completely effective against the targeted parasites, including parasites that have developed resistance.

Research conducted in 2012 on WA Farms, confirmed the presence of resistance to three single actives available for use in cattle at that time. This work indicated that small intestinal worm (Cooperia oncophora) resistance against ivermectin (macrocyclic lactone) was present on two-thirds of farms. Importantly, ivermectin was fully effective when tested against brown stomach worm (Ostertagia ostertagi). The benzimidazole (white) and levamisole (clear) drenches were fully effective against small intestinal worms, but resistance was present in brown stomach worms on about half of the farms tested. Research in other states also showed the presence of similar or greater resistance.

While certain cattle worms had resistance to individual actives, the results showed that using combination products could fully control these parasites and prevent further development of resistance.

Combination and mixtures

Both dual (2 actives) and triple (3 actives) combinations are available.

Available combination and mixture treatments are listed in Table 1 below.

Types of mixtures and combinations

A guide to the different actives and the pests they affect are in Table 1. Information on the individual actives is available under their respective chemical group. See the Products Search for the appropriate formulation and application method for your target pest

Table 1. Mixtures and combinations, their actives and a summary of the targeted parasites for which formulations are registered for. Boxed check marks indicate the pest targeted by multiple actives.

Chemical

Pests targeted (may vary with formulation)

Worms

Flies

Ticks

Lice

Mites

Round worm

Intestinal tapeworm

Liver fluke

Buffalo fly

Stable fly

Premises flies

Fly strike

Cattle tick

Paralysis tick

Bush tick

Combination (all actives target boxed parasite)

Abamectin and levamisole

√

√

√

Ivermectin and fluazuron

√

√

√

√

Moxidectin and levamisole

√

Abamectin, levamisole and oxfendazole

√

Beta-cyfluthrin and imidacloprid

√

Cypermethrin and chlorfenvinphos

√

√

√

√

Cyphenothrin and delta-tetramethrin

√

Deltamethrin and ethion

√

√

Clorsulon and nitroxynil

√

Imidacloprid and beta-cyfluthrin

√

Mixtures (multiple targets)

Macrocyclic lactone and triclabendazole

√

√

√

√

Ivermectin and clorsulon

√

√

√

√

Oxfendazole and triclabendazole

√

√

√

Levamisole and oxyclozanide

√

√

Mixtures and combinations (multiple targets, primary target of actives boxed)

Ivermectin, nitroxynil, and clorsulon

√

√

√

√

Synthetic pyrethroids and pyrethrins (SP)

What do they treat?

Flies, Ticks, Lice

When using SPs to target a particular parasite, be aware that they will also treat any other of the above-mentioned parasites that are present. This can increase the development of chemical resistance by all of these parasites each time an SP product is used.

Note: Very toxic to fish and to beneficial insects such as bees

How can they be administered?

A variety of application methods for administering pesticide products to cattle are in use.

Ear tags Spray on Pour on Dip Powder Premises surface spray

• Ear tags, spray on, pour on and dips should be correctly applied to all cattle in a mob to ensure effective control.
• Follow label instructions.

Resistance

Reported in: Flies, Ticks

• SP resistance has been detected in certain areas and once present it can build up very quickly.
• Under-dosing will lead to poor pest control and may hasten the development of resistance to the chemical.

What is resistance?

Safety

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

• SPs and pyrethrins are generally regarded as compounds of low-toxicity but can cause eye and skin irritation in some people.

Withholding

Withholding periods are mandatory with all registered veterinary products used to treat animals for internal and external parasites.

• Always check the product label before use for specific withholding periods (WHP) and export slaughter interval (ESI) periods. Current ESI periods can be confirmed on the APVMA website.

Types of synthetic pyrethroids and pyrethrins

A guide to the different actives and the pests they affect are in Table 1. See the Products Search for the appropriate formulation and application method for your target pest. Note combinations and mixtures of actives may improve treatment efficacy.

Table 1. Synthetic pyrethroids and pyrethrins, their actives, combinations and mixtures and a summary of the targeted parasites for which formulations are registered for. Boxed check marks indicate the pest targeted by multiple actives.

Chemical	Pests targeted (may vary with formulation)
	Worms	Flies			Ticks	Lice	Mites
		Buffalo fly Stable fly	Premises flies*	Fly strike	Cattle Paralysis Bush
SPs
Cyfluthrin			√
Beta-cyfluthrin		√	√
Lambda-cyhalothrin			√
Cyphenothrin			√
Alpha-cypermethrin		√	√		√	√
Zeta-cypermethrin		√				√
Deltamethrin		√	√		√	√
Esfenvalerate			√
Fenvalerate		√
Flumethrin					√
Permethrin		√	√			√
Delta-tetramethrin			√
Pyrethrins			√	√
Combination (all actives target boxed parasite)
Beta-cyfluthrin and imidacloprid			√
Cypermethrin and chlorfenvinphos		Buffalo fly √			Cattle √ and other ticks	√
Cyphenothrin and detla-tetramethrin			√
Deltamethrin and ethion		Buffalo fly √			Cattle √ and bush tick

 *IRAC Mode of Action group 3A

What are they?

Synthetic pyrethroids are synthetically manufactured compounds with a molecular structure similar to naturally occurring pyrethrins. Natural pyrethrins are extracts from the flowers of certain plants which have insecticidal and repellent properties.

How do they work?

SPs have a broad spectrum of activity, they are non-systemic, very fast-acting chemicals that act by contact. Susceptible insects are knocked down and die very quickly. Many SPs and natural pyrethrins also have a repellent effect.

SPs affect the axons of nerves causing paralysis of target organisms by keeping sodium channels open in the nerve membranes. The resultant constant nerve excitement eventually causes insect paralysis. This toxic effect also occurs in vertebrates since the cellular membranes work in a similar manner.

Natural pyrethrins are unstable when exposed to sunlight limiting protection for animals to a few days at most.

Organophosphates (OP)

What do they treat?

Flies, Ticks, Lice

When using OPs to target a particular parasite, be aware that they will be treating any other of the above-mentioned parasites that are present. This can increase the development of chemical resistance by all of these parasites each time an OP product is used.

Note: Toxic to humans

How can they be administered?

A variety of application methods for administering pesticide products to cattle are in use.

Ear tags Spray on Dip Backrubber Powder

Premises surface spray Premises paintable bait

• Ear tags, spray on, pour-on and dips should be correctly applied to all cattle in a mob to ensure effective control.
• Only powder treat affected animals for flystrike.

Resistance

Reported in: Flies, Ticks

What is resistance?

Safety

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

• Toxic to humans.
• Occupational health and safety risks necessitate greater care during storage, use and disposal of OPs.
• OPs may be absorbed through human skin, inhaled in vapours or absorbed by ingestion.
• Absorption is enhanced by moisture on the skin surface (e.g. sweat or contaminated clothes).
• OPs are readily absorbed through breaks in the skin, such as cuts, cracked skin and sores.
• Use appropriate personal protective equipment (PPE) for application method.

Withholding

Withholding periods are mandatory with all registered veterinary products used to treat animals for internal and external parasites.

• Always check the product label before use for specific withholding periods (WHP) and export slaughter intervals (ESI) periods. Current ESI periods can be confirmed on the APVMA website.

Types of organophosphate

A guide to the different actives and the pests they affect are in Table 1. See the Products Search for the appropriate formulation and application method for your target pest. Note combinations and mixtures of actives may improve treatment efficacy.

Table 1. Organophosphates, their actives, combinations and mixtures and a summary of the targeted parasites for which formulations are registered for. Boxed check marks indicate the pest targeted by multiple actives.

Chemical	Pests targeted (may vary with formulation)
	Worms	Flies			Ticks	Lice	Mites
		Buffalo fly Stable fly	Premises flies*	Fly strike	Cattle tick Paralysis tick Bush tick
OPs
Azamethiphos			√
Chlorfenvinphos		√			√	√
Chlorpyrifos		√				√
Coumaphos		√
Ethion		√
Maldison			√
Pirimphos-methyl			√
Tetrachlorvinphos		√
Trichlorfon			√
Combination (same target boxed)
Chlorfenvinphos and cypermethrin		Buffalo fly √			Cattle √ and other ticks	√
Ethion and deltamethrin		Buffalo fly √			Cattle √ and bush tick

*IRAC Mode of Action group 1B

What are they?

Organophosphates (OPs) are synthetic chemicals that belong to the organic esters of phosphoric acid. OPs kill insects by altering normal neurotransmission.

How do they work?

OPs have a broad spectrum of activity.

Most OPs act by contact with the insect—a few are also systemic. OPs exert their effects on the nervous system of organisms. As such, they are relatively fast-acting and susceptible insects will be killed within 4–8 hours of exposure.

OPs cause accumulation of acetylcholine (ACh) by blocking the enzyme (acetylcholinesterase) which normally breaks down this neurotransmitter. ACh is common to both insects and mammals and as a result, OPs are toxic to humans.

Insect Growth Regulators (IGR)

What do they treat?

Premises flies Cattle tick Lice

When using the product to target a particular parasite, be aware that it will be treating any other of the above-mentioned parasites that are present. This can increase the development of chemical resistance by all of these parasites each time an IGR product is used.

Note: Toxic to spiders, crustaceans and beneficial insects such as bees and predators of house fly larvae.

How can they be administered?

A variety of application methods for administering pesticide products to cattle are in use.

Pour on Premises surface spray Water soluble granules for premises

Resistance

Reported in: Flies, Cattle tick

What is resistance?

Safety

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

• IGRs have selective toxicity and therefore are relatively safe to human health.
• Ensure appropriate on-farm disposal of spent fluids. It is important that wastes do not enter watercourses where they may cause environmental harm, or accumulate in areas grazed by animals as IGRs bind tightly to soil and degrade slowly.

Withholding

Withholding periods are mandatory with all registered veterinary products used to treat animals for internal and external parasites.

• Always check the product label before use for specific withholding periods (WHP) and export slaughter interval (ESI) periods. Current ESI periods can be confirmed on the APVMA website.

Types of insect growth regulators

A guide to the different actives and the pests they affect are in Table 1.See the Products Search for the appropriate formulation and application method for your target pest. Note combinations and mixtures of actives may improve treatment efficacy.

Table 1. Insect growth regulators, their actives and mixtures and a summary of the targeted parasites for which formulations are registered for.

Chemical	Pests targeted (may vary with formulation)
	Round worm	Flies		Cattle tick	Lice	Mites
		Buffalo fly	Premises flies*
IGR
Cyromazine			√
Diflubenzuron			√		√
Fluazuron				√
Mixtures (multiple targets)
Fluazuron and ivermectin	√	√		√	√	√

What are they?

Insect growth regulators (IGRs) are sometimes called development inhibitors. The chemicals interrupt insect growth and development by interfering with the production of chitin – the compound insects, ticks, lice and mites use to make their exoskeleton.

How do they work?

As arthropods grow their exoskeleton becomes too small and they have to shed this outer skin (moult) to continue growing. This new skin requires chitin and IGRs inhibit this process causing the larvae to stop growing and developing into an adult. IGRs also inhibit egg hatching.

IGRs are slow-acting compounds that eliminate infestations over many weeks. Adult stages are not killed by IGRs because they do not moult.

Diflubenzuron is a broad spectrum larvacide used in bait formulations for nuisance flies and for treating lice on cattle.

Cyromazine is a narrow spectrum larvacide that is only effective against dipteran larvae i.e. flies. As cyromazine is specific against house flies it is not toxic to the beneficial insects that live in livestock manure if used as directed.

Fluazuron is effective against ticks, but not flies.

Amitraz

What does it treat?

Cattle tick, Paralysis tick, Bush tick

Note: Very toxic to aquatic life with long lasting effects

How can it be administered?

A variety of application methods for administering pesticide products to cattle are in use.

Spray on, Dip

• Treat all animals in a mob to ensure effective control.

Resistance

Reported in: Cattle tick

What is resistance?

Safety

Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.

• Amitraz may be harmful if swallowed, could cause lung damage if inhaled and may cause short term eye irritation.

Withholding

Withholding periods are mandatory with all registered veterinary products used to treat animals for internal and external parasites.

• Always check the product label before use for specific withholding periods (WHP) and export slaughter interval (ESI) periods. Current ESI periods can be confirmed on the APVMA website.

Types of amitraz

A guide to the pests that amitraz affects are in Table 1. See the Products Search for the appropriate formulation and application method for your target pest.

Table 1. Amitraz active and the targeted parasites for which formulations are registered for.

Chemical	Pests targeted (may vary with formulation)
	Worms	Flies	Ticks			Lice	Mites
			Cattle tick	Paralysis tick	Bush tick
Amitraz			√	√	√

What is it?

Amitraz is a chemical of the formamidine group developed in the early 1970’s as a broad spectrum insecticide and acaricide against ectoparasites such as ticks and mites.

Amitraz is an acaricide widely used in the control of organophosphate and synthetic pyrethroid resistant cattle ticks.

How does it work?

Acts as an agonist on octopamine receptors causing a range of behavioural changes including detachment and paralysis.