Liver microsomes are used extensively in human pharmaceutical development to study the metabolism of compounds of interest; however, they are rarely part of the development of toxicants for the control of wildlife. Liver microsome samples from wildlife of interest would likely be harvested in the field without access to laboratory perfusion equipment. Therefore, the metabolic activity of microsomes from perfused and non-perfused livers was compared. There was no significant difference in diphacinone metabolism by liver microsomes from both perfused and non-perfused Wistar rat livers, although chlorophacinone metabolism was significantly different. There are often significant differences in metabolism between species that can be utilized to increase toxicant specificity. In this study bobwhite quail liver microsomes metabolized more diphacinone and chlorophacinone than both Wistar and brown rats. This information can be used during toxicant development to help determine the most sensitive species to toxicants of interest. Additionally, the effect of incubation time on toxicant metabolism was examined to determine optimal experimental conditions. The data from these experiments support the use of liver microsomes as a tool to be used during toxicant development to provide information that can be incorporated into whole animal studies.

The mountain beaver is a fossorial rodent species endemic to the Pacific Northwest and portions of California. This herbivore is managed as a pest species because of the impact it has on newly planted Douglas-fir seedlings. Currently, managers are limited to trapping for population control; however, in Washington trapping has been further curtailed by anti-trapping legislation. Presently there are no registered underground toxicants for mountain beaver control. We have documented the efficacy of chlorophacinone, presented in daily doses, as a possible alternative for mountain beaver control. Daily baiting would be unreasonable and costly alternative for timber managers, so we conducted a series of tests to determine if a single or double baiting was efficacious. In addition, we tested the caching behavior of the mountain beaver when offered bags of oats. This behavior may help reduce impacts to non-target species as well reduce environmental exposure and degradation. Mountain beaver readily cached bags of chlorophacinone within their artificial burrows, and efficacy of a one-time and two-time dose was 100%. We determined that even with the highest chlorophacinone residuals (0.354 ppm) that the risk quotient for mink and red-tailed hawk was exactly at the level of concern that EPA recognizes for endangered and threatened species.

Lettuce is an important economic crop in California, with approximately 101,000 ha in production and a value of $1.3 billion in 2002. Bird damage to lettuce in the San Joaquin Valley, the central coast, and southern California is believed to amount to millions of dollars annually. We evaluated the effectiveness of Flight Control™ (50% anthraquinone applied at 10 L/ha) as a foliar spray for protecting emerging lettuce seedlings from depredation by horned larks. In field enclosure trials conducted near Huron, in the San Joaquin Valley of California, damage to treated lettuce seedlings was 8.5%, compared to 68% damage to untreated seedlings. In a field test, anthraquinone residues on the day of treatment averaged 570 ppm and at Day 50 after treatment were lower than the method of detection (0.063 ppm). However, horned lark numbers using test sites were too low to detect any differences in damage among treated and untreated sites. Anthraquinone offers promise for reducing bird depredations to sprouting lettuce, but additional testing should be conducted to evaluate this repellent in a large-scale field setting.

The U.S. Department of Agriculture distributes more than 10 million tetracycline-containing rabies vaccine baits to control the spread of wildlife-vectored rabies to humans, pets, and livestock. To estimate the percent of target species consuming the baits, raccoons were collected in baited areas and teeth were analyzed for the presence of the tetracycline biomarker. Several incidents of low biomarker detection rates prompted an investigation of the stability of the biomarker in the baits. These studies indicated that a portion of the tetracycline was converted to epitetracycline. Additionally, significant quantities of both compounds were trapped in the polymer which is homogeneously distributed throughout the bait. This situation is likely responsible for low biomarker detection rates. To alleviate this problem, we developed an alternative bait matrix which permits increased stability and bioavailability of the tetracycline biomarker. This new bait matrix increased the availability of the tetracycline marker from 25.2 to 87.3% and decreased epitetracycline formation from 12.4 to 3.6%.

We evaluated a polyethylene bulb reservoir fabricated at the Pocatello Supply Depot, Pocatello, Idaho, as a potential cost savings replacement for the McBride rubber device that is used as a tranquilizer trap device (TTD). The polyethylene devices, also called pipette TTDs, were formulated with 0.6 g of propiopromazine hydrochloride (PPZH) and 0.4 g of ascorbic acid, an antioxidant. The pipette bulb was secured to a 1.6 mm-diameter cable and the cable was attached to the trap jaw. TTD testing was conducted during routine operational control under an Investigational New Animal Drug application (INAD 9528) from the U.S. Food and Drug Administration. The targeted animals were feral dogs in Guam, coyotes in Utah and Idaho, and gray wolves in Minnesota. Various degrees of tranquilization, ranging from quietness and lack of attention to sleepiness, were observed in the animals. Percent of tranquilization effects observed in feral dogs, coyotes, and wolves were 67%, 90%, and 67%, respectively. Evidence of reduced struggling and reduced injuries to feet and legs was observed. Tranquilization effects were also observed in non-target animals such as badgers, skunks, and raccoons. A mortality that was probably related to heat stress was recorded in one juvenile wolf. A major drawback of the pipette TTD was leakage at the stem attached to the trap jaw. Degradation of PPZH was also observed but was reduced compared to formulations without ascorbic acid.