| Popis: |
Research to assess the use of diphacinone as a predacide was divided into three primary phases: (1) acute oral toxicity tests with laboratory (captive) and free-ranging coyotes (Canis latrans); (2) residue analysis in tissues from coyotes killed by diphacinone; and (3) secondary toxicity tests with diphacinone meat baits fed to male albino rats (Rattus norvegicus) and golden eagles (Aquila chrysaetos). The LD 5 0 with 95 percent confidence limits in captive coyotes was 0.6 (0.3 to 1.2) mg/kg. Free-ranging coyotes were captured, treated, and released to determine if efficacy was different from captive animals. Each was equipped with a mortality transmitter and tracked for a minimum of 21 days. The statistical method was not appropriate to calculate an LD 5 0 in free-ranging animals; however, there appeared to be no major differences in toxicity as compared with captive animals. One male free-ranging coyote survived a dose of 2.5 mg/kg and one male captive coyote survived a dose of 1.25 mg/kg. These data indicate high individual variation in the toxic response to diphacinone. Time to death did not differ between the two groups; that is, free-ranging coyotes averaged 9.6 days (range 8 to 16) and captive animals averaged 10.4 days (range 6 to 17). Secondary toxicity tests were conducted with male albino rats fed a meat (muscle tissue) bait for 6 days from captive coyotes killed with diphacinone. The highest diphacinone residue in these baits was 0.5 ppm and four of eight rats that fed upon it died. Hence, there is a secondary hazard to susceptible animals that feed repeatedly on tissue containing at least 0.5-ppm diphacinone. In most animals the small intestine, liver, or kidney contained more than 0.5 ppm, and these tissues have a higher potential for secondary toxicity than muscle. Seven golden eagles were fed sheep meat containing 2.7-ppm diphacinone as the sole source of food in 5- and 10-day feeding tests. All eagles survived, but various degrees of toxicity were noted. |
