The efficacy of avermectins (ivermectin, doramectin and abamectin) as treatments for infestation with the tick Haemaphysalis longicornis on rabbits in Korea

The efficacy of a single subcutaneous injection of an avermectin (ivermectin, doramectin, or abamectin) as a treatment for infestation with nymphal and adult Haemaphysalis longicornis was evaluated in 24 New Zealand White rabbits. Two days after artificial infestation with nymphs or adult ticks, the rabbits were randomly allocated to three treatment groups (to be treated with ivermectin, doramectin, and abamectin) and a control group. The animals in the treatment groups were injected with commercial injectable formulations of each avermectins at a dose of 200 μg/kg live weight. The results showed that on rabbits treated with these avermectins, nymphs and female ticks had significantly reduced weight, nymphs had reduced moulting success rates, and females had inhibited ovary development. Among the treatments, doramectin was most effective in reducing the weight of nymphs (weight was reduced by 80%) and females (by 97.3%); ivermectin was most effective in reducing the moulting success rate in nymphs (by 55%); and both doramectin and abamectin were effective in inhibiting the development of female ticks' ovaries (by 46%). Data from this investigation show that avermectins are suitable for the control of H. longicornis on rabbits in Korea.