Susceptibility test to anticoagulant rodenticides in species endemic to the Ogasawara Islands

<p>The Ogasawara Islands, which have a unique ecosystem, are facing the problem of ecosystem disturbance caused by non-native species such as rats, and have taken countermeasures by dusting with an anticoagulant rodenticide (ARs). ARs act on VKOR to stop the vitamin K cycle of the blood coagulation system, causing systemic bleeding and death of the target. Although ARs are widely used, primary exposure by direct ingestion of the ARs by non-target animals and secondary exposure by ingestion of rodents killed by the ARs are major problems. Then, when using ARs, it is necessary to consider whether they threaten other species inhabiting the target area. In particular, the Ogasawara Islands are home to endangered endemic species, such as the Ogasawara Greenfinch (Chloris kittlitzi) and the Bonin flying fox (Pteropus pselaphon), and thus primary exposure to ARs may be a concern. Then, evaluating their susceptibility is important.</p><p>In this study, we aimed to evaluate the effects of ARs application on endemic species in these islands. We used microsomes extracted from the livers of the Greenfinch (C. sinica), a sister species of the Ogasawara Greenfinch, and the Bonin flying fox and conducted in vitro susceptibility testing. As a result of the metabolism test, in addition to warfarin (WF), its hydroxylated forms, 4’-, 6-, and 8-OH-WF, were identified in the Greenfinch, and 4’-, 6-OH-WF in the Bonin flying fox, suggesting that metabolism for these substances take place. In addition to this study, we are now conducting a VKOR inhibition test and plan to conduct a more detailed evaluation.</p>