Amitraz is a formamide exhibiting both acaricidal and insecticidal activity and is frequently used by beekeepers to protect honeybee colonies against Varroa destructor mites. The aim of this apiary trial was to evaluate the impact of honeybee colony fumigation with amitraz on the level of contamination of honey stored in combs. Experimental colonies were fumigated four times every four days with one tablet of Apiwarol per treatment. Honey was sampled from combs of brood chambers and combs of supers one day after each amitraz application and from harvested honey. Amitraz marker residues (as a total of amitraz and metabolites containing parts of molecules with properties specific to the 2,4-DMA group, expressed as amitraz) were evaluated in honey. All analysed samples were contaminated with amitraz metabolites. 2,4-DMA and DMPF were the most frequently determined compounds. The average concentration of amitraz marker residue in honey from groups where a smouldering tablet was located directly in beehives was significantly higher than that of residue in honey from groups with indirect smoke generation. No significant effect on the honey contamination deriving from the place where it was exposed to smoke (combs of brood chambers and supers) was noted. Amitraz marker residues exceeded the MRL in 10% of honey samples from combs. Fumigation of beehives with amitraz results in contamination of honey stored in combs.

In veterinary medicine amitraz has been used as an insecticide to eliminates mites, lice, and ticks in dogs, cats, goats, swine and cattle. The objective of present study was to developed an analytical method using one-step extraction and determination of the amitraz in veterinary drugs by liquid chromatography (LC). The amitraz was analyzed by LC equipped with Waters XTerra RP18 (4.8×250 mm; 5 ㎛; Waters, USA) analytical column, using 75% acetonitrile (acetonitrile/D.W; 75/25) at 1.0 ml/min. The UV-VIS detection of amitraz was made at 290 nm. Calibration graphs were linear with very good correlation coefficients (r² greater than 0.9999) from 80~120 ㎍/ml. The limit of detection was 0.09 ㎍/ml and limit of quantification was 0.27 ㎍/ml. The method showed good intra-day precision (CV 0.05~0.09%) and inter-day precision (CV 0.06~0.18%).

This study investigated the potential effects of amitraz on the pre- and postnatal development, behavior, and reproductive performance of offspring of parent rats given amitraz during pre-mating, gestation, and lactation. The test chemical was administered via the drinking water containing 0, 40, 120, and 360 ppm to male rats from 2 weeks before mating to the end of 14-day mating period and to females from 2 weeks before mating, throughout mating, gestation and lactation up to weaning. Based on fluid consumption, the male rats received an average of 0, 5.7 ± 1.33, 13.2 ± 2.08, and 35.8 ± 3.42 mg/kg/day amitraz, and the female rats received an average of 0, 8.7 ± 4.42, 20.1 ± 9.60, and 47.6 ± 22.38 mg/kg/day amitraz, respectively. At 360 ppm, an increase in the incidence of abnormal clinical signs, a suppression in the body weight gain, a decrease in the food consumption and litter size, an increase in the post-implantation loss, and a decrease in the seminal vesicle weight were observed in the parent animals. In addition, a suppression in the body weight gain, a decrease in the grip strength, a delay in the negative geotaxis, an increase in the pre- and post-implantation loss, and a decrease in the number of live embryos were observed in the offspring. At 120 ppm, suppressed body weight gain and reduced food consumption were observed in the parent rats. Suppressed body weight gain and decreased grip strength were also observed in the offspring. There were no signs of either reproductive or developmental toxicity at 40 ppm. Under these experimental conditions, the no-observed-adverse-effect level of amitraz for parent rats and their offspring was estimated to be 40 ppm in rats.

A 3-year-old female Thoroughbred racehorse was presented following the accidental oral and skin administration of amitraz. This case report describes the clinical signs and the treatment of this horse. Clinical signs of amitraz toxicosis are associated with the stimulation of alpha2-adrenergic receptors. Amitraz is seldom fatal because the effects can be reversed by alpha2-adrenergic antagonists. The horse displayed typical clinical signs of colic, including pawing, small hard drops, tranquillisation, depression, ataxia, muscular incoordination and impaction colic lasting up to 7 days. The syndrome was accompanied by mild dehydration. The horse survived after persistent symptomatic treatment, including the giving of intravenous fluids, antibiotics, multiple doses of mineral oil per os, nonsteroidal anti-inflammatory drugs and dexamethasone intramuscularly and intravenously.

Evaluation of amitraz against ticks and mites infestation in cattle and sheep in comparison with diazinon and deltamethrin was performed. Amitraz showed over 95 % inhibition of oviposition and hatching of laid eggs at dilution of 1:500 while diazinon and deltamethrin produced around 90 % inhibition of oviposition at the same dilution. Fed ticks were more susceptible for all tested acaricides than the unfed ticks, where amitraz reached its full effectiveness (100 % kill of fed and unfed) 2 weeks after application while diazinon and deltamethrin produced over 90 % at the same dilution. Spraying application of amitraz 12.5 % resulted in 100 % tick control by day 5 and the effect was maintained for further 28 days whereas diazinon and deltamethrin were fully effective by days 9 and 13, respectively and their efficacy were maintained for 16 and 20 days, respectively. Spraying application of amitraz 12.5 % produced 100 % efficacy as no live mites were found on day 17 and maintained in full effectiveness till day 33 where respraying was needed. In conclusion, amitraz produced rapid detachment of ticks from animals; its residual effect was long and protected animals from re-infestation for 29 days and was able to eradicate psoroptes mite infestation in sheep.

The present study was carried out to investigate the potential adverse effects of amitraz on pregnant dams after maternal exposure during the gestational days (GD) 1 through 19 in Sprague-Dawley rats. The test chemical was administered orally to pregnant rats at dose levels of 0, 3, 10, or 30 mg/kg/day. During the test period, clinical signs, mortality, body weights, food consumption, serum biochemistry, gross findings, organ weights and reproductive findings on GD 20 were examined. In the 30 mg/kg group, an increase in the incidence of abnormal clinical signs and death, a suppression in the body weight gain, and a decrease in the food consumption were observed.