Abamectin is a mixture of avermectins containing > 80% avermectin B1a and < 20% avermectin B1b. These two components, B1a and B1b have very similar biological and toxicological properties . The avermectins are insecticidal or anthelmintic compounds derived from the soil bacterium Streptomyces avermitilis . Abamectin is a natural fermentation product of this bacterium . Abamectin is used to control insect and mite pests of a range of agronomic, fruit, vegetable and ornamental crops, and it is used by homeowners for control of fire ants . Doses of 50 to 200 ug/kg of ivermectin, a similar member of the avermectin family of comounds, is widely used to treat humans in the World Health Organization onchocerciasis (river blindness) program 。
Abamectin is a highly toxic material, however most formulated products containing abamectin are of low toxicity to mammals . Emulsifiable concentrate formulations may cause moderate eye irritation and mild skin irritation . Symptoms of poisoning observed in laboratory animals include pupil dilation, vomiting, convulsions and/or tremors, and coma .
Abamectin acts on insects by interfering with neural and neuromuscular transmission. It acts on a specific type of synapse located only within the brain and is protected by the blood-brain barrier. However, at very high doses, the mammalian blood-brain barrier can be penetrated, causing symptoms of CNS depression such as incoordination, tremors, lethargy, excitation and pupil dilation. Very high doses have caused death from respiratory failure .