Elucidation of the Influence of the Rodenticide Spraying on Wildlife in the Ogasawara Islands
Principal Investigator: Shouta NAKAYAMA
Institution:

Hokkaido University, Sapporo City,Hokkaido 060-0818, JAPAN

Tel: +81-11-706-5105 / Fax: +81-11-706-5105
E-mail: shouta-nakayama@vetmed.hokudai.ac.jp
Cooperated by: Graduate School of Veterinary Medicine, Obihiro University of Agriculture andVeterinary Medicine[Abstract]
Key Words:

Wildlife, rodenticide, susceptibility, Ogasawara Islands, animal species difference,

endemic species, rare species
Although anticoagulant rodenticides (ARs) are effectively used for the control of invasiverodents, nontarget species are also frequently exposed to ARs and secondary poisonings occurwidely. However, little data is available on the effects of ARs, especially on wildlife. In thisstudy, we evaluated the anti-coagulant rodenticides sensitivity in four main species in theOgasawara Islands: the red-faced wood pigeon, the Ogasawara Buzzard, the Bonin flying fox, andthe green sea turtle, to provide data for policy decisions related to rodenticides use. In Vitro
metabolism studies suggested that pigeon rapidly metabolized warfarin in the liver and are lesssusceptible to its effects, whereas green turtles have a lower capacity to metabolize warfarin in
the liver and are more susceptible to warfarin. Compared to rats, bats showed a rapid decrease inblood warfarin and diphacinone. In Vivo studies showed that warfarin metabolism and excretion was
higher in buzzard and pigeons than in chickens. In Vivo studies of warfarin in green sea turtles
showed that warfarin remained in the blood for a long period of time. The inhibition rate of VKOR
activity in the black rat, the target species for rodenticides, was 99.2%, whereas the inhibition
rate of VKOR activity in the pigeon was about 60%, indicating that the pigeon is expected to beless sensitive to warfarin than the rat. The low IC50 and low VKOR activity of buzzard suggeststhat they may be susceptible to rodenticides. In Vivo study using Egyptian bats suggested thatbat would be more resistant to warfarin and diphacinone than rats. In Vitro VKOR activity inhibition
by diphacinone showed comparable inhibition rate in bats compared to rat. These results suggestthat bats are lower or comparative sensitivity with rats. In Vitro VKOR activity inhibition bywarfarin suggested that sea turtles would be more sensitive to rodenticides compared to rats.
Furthermore, analysis of blood coagulation time in sea turtles in In Vivo administration study
revealed that blood coagulation time was prolonged even long after of warfarin administration.
The risk of exposure of rodenticides from the marine environment may be higher in green turtles.
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