Amitraz is a widely used pesticide, functioning as an acaricide and insecticide in both veterinary and agricultural fields. It belongs to the formamidine chemical class, known for its effectiveness against mites and ticks. Developed in the late 1960s, Amitraz is a non-systemic compound, meaning it works by contact rather than being absorbed into the host’s bloodstream. Its primary application is controlling external parasites that affect animal health and crop yields.
How Amitraz Affects Target Pests
Amitraz works by disrupting the nervous system of target pests like ticks and mites, leading to paralysis and eventual death. The mechanism of action primarily involves interaction with specific neurological receptors unique to invertebrates. Amitraz and its active metabolite act as agonists on octopamine receptors within the arthropod central nervous system.
Octopamine is an invertebrate neurotransmitter that regulates functions like behavior and movement, similar to norepinephrine in mammals. By binding to and activating these receptors, Amitraz causes an overexcitation of the pest’s nervous system. This overstimulation prevents the pest from feeding and moving, resulting in rapid detachment from the host and death. The molecule is also thought to inhibit monoamine oxidases and prostaglandin synthesis, contributing to its toxic effect.
Common Uses in Veterinary Medicine and Agriculture
Amitraz is a versatile agent used to protect both domestic animals and food crops worldwide. In veterinary medicine, it is highly valued for controlling ectoparasites on dogs and livestock. For dogs, Amitraz is commonly used in impregnated collars, topical dips, and washes to treat infestations of ticks, lice, and mites, including severe cases like demodectic mange.
Application methods vary depending on the animal. Cattle and pigs are often treated with sprays, while sheep and goats typically receive dips. Formulations are available as wettable powders, emulsifiable concentrates, and liquids, allowing for flexible application.
A significant application is in apiculture, where Amitraz controls the Varroa destructor mite, a devastating parasite of honeybee colonies. For this purpose, it is supplied in impregnated strips suspended inside the beehive. In agriculture, Amitraz is applied as an insecticide and acaricide to protect fruit trees, such as pears, from pests like pear psylla and various mites. It also controls whiteflies and mites on crops like cotton and certain vegetables.
Certain animals, including cats and horses, are particularly sensitive to Amitraz and are generally excluded from treatment due to the risk of adverse effects. Cats lack the necessary metabolic pathways to process the compound safely, making them highly susceptible to toxicity.
Toxicity and Safety Precautions
While Amitraz effectively targets the invertebrate nervous system, its structure allows it to interact with the alpha-adrenergic receptors found in mammals. This alpha-2 adrenergic agonist activity is the primary cause of systemic toxicity in non-target species. When ingested or absorbed in high concentrations, this action leads to central nervous system and cardiovascular effects.
In animals, especially dogs given an overdose, and in humans, symptoms of poisoning include sedation, central nervous system depression, and vomiting. It also causes decreased heart rate (bradycardia), low blood pressure (hypotension), and pupil constriction (miosis). Metabolic changes like hyperglycemia can occur, and Amitraz poisoning often mimics a clonidine-like syndrome.
For human applicators, the highly lipid-soluble nature of Amitraz means it can be rapidly absorbed following oral ingestion, inhalation, or dermal contact. Safety precautions involve using appropriate personal protective equipment (PPE), such as gloves, protective clothing, and eye protection, to minimize exposure. Adequate ventilation should also be maintained when applying dips or sprays in enclosed areas.
Ingestion requires immediate medical attention. While there is no specific antidote, supportive care, including respiratory support and blood pressure management, is highly effective. The prognosis is generally good within 12 to 48 hours. Regulatory bodies require careful adherence to prescribed concentrations and application methods to mitigate risk.