Thomas M. Primus

Anthraquinone protects rice seed from birds

Application of bird-repellent chemicals to seed prior to planting is one possible approach to reducing bird damage to rice. Anthraquinone is a promising seed treatment compound, and in this paper we describe a sequence of tests evaluating a formulated commercial anthraquinone product. In l-cup cage tests, rice consumption by individual male red-winged blackbirds (Age&w phoeniceus) and female boat-tailed grackles (Quiscalus major) was reduced 64-93% by 0.5 and 1.0% (g/g) anthraquinone treatments. Daily rice consumption by single male boat-tailed grackles tested in large enclosures was reduced from > 14 g in pretreatment to < 1 g by a 1.0% treatment. One of five test birds ate nothing during a 1 day post-treatment session. In a 7 day trial within a 0.2 ha flight pen, a group of four male grackles consumed 1.3% of anthraquinone-treated rice seed compared to 84.1% of sorghum, a nonpreferred alternate food. At two study sites in southwestern Louisiana, loss of rice sprouts in 2 ha plots sown with anthraquinone-treated seed was 0 and 12% compared to losses of 33% and 98% in nearby untreated plots. The formulation performed well at every stage of testing, and further development of anthraquinone products for bird-damage management is warranted. Published by Elsevier Science Ltd

Assessing the Hazard to Granivorous Birds Feeding on Chemically Treated Seeds

Current methods for evaluating hazards to seed-eating birds are based on estimated exposure per unit area and assume that birds ingest all of the chemical on a treated seed. In an earlier study, however, it was determined that red-winged blackbirds removed only about 15% of an insecticidal treatment applied to individual rice seeds. Here, we extend those -ndings by examining the seed-handling behavior of four granivorous bird species exposed to millet, rice, sunNower and sorghum treated with imidacloprid. Mourning doves (Zenaida macroura L.) swallowed the seed whole. House -nches (Carpodacus mexicanus Mue ller), red-winged blackbirds (Agelaius phoeniceus L.) and boat-tailed grackles (Quiscalus major Vieillot) discarded the seed hulls, however, and removed only 15E40% of the initial chemical treatment. Residues on seed hulls decreased as handling time increased. SunNowers had the lowest residues because birds repeatedly handled the hull to remove bits of the oily kernel. These results suggest that avian hazard assessment methods should incorporate species-typical seed-handling behavior to assess more accurately birdsI exposure to chemicals on di†erent types of seed.

Consumption of fipronil‐treated rice seed does not affect captive blackbirds

Fipronil is an insecticide developed for use on rice seed and other crops. In a series of cage and pen trials, we evaluated the responses to dyed, fipronil-treated rice seed of three bird species likely to encounter it in the field. Individually caged red-winged blackbirds (Agelaius phoeniceus), brown-headed cowbirds (Molothrus ater), and boat-tailed grackles (Quiscalus major) displayed no evidence of adverse reaction to treated seed. Chemical analyses of hulls from treated seeds eaten by captive birds revealed that 10-20% of the fipronil originally present was removed during feeding. In group enclosures, male red-winged blackbirds ate as much fipronil-treated rice as they did dyed, untreated seed. In four-day tests within a 0.2-ha flight pen, 10-bird blackbird flocks removed 11.4% of fipronil-treated seed from a test plot compared to 12.5% of dyed, untreated seed removed from the alternate plot. When the alternate plot contained undyed rice, however, seed removal from the treated plot averaged 2.4% compared to 28.9% from the alternative plot, suggesting that the groups of test birds avoided treated seed based on its appearance. We conclude that 325 and 500 mg kg -1 fipronil applications alone do not affect avian feeding activity.

The effect of cooking on diphacinone residues related to human consumption of feral pig tissues

We examined feral pig tissues to determine whether the potential hazard of consuming meat from pigs previously exposed to diphacinone rodenticide baits was reduced by cooking. Residue levels were measured in cooked and uncooked tissues of feral pigs exposed to sub-lethal quantities of the anticoagulant rodenticide. Pigs were provided large amounts of baits or untreated food to consume, then euthanized prior to the onset of symptoms indicative of rodenticide poisoning or sickness. For analysis, we grouped pigs into three levels of mean diphacinone consumption: 0, 3.5, and 7.4 mg/kg. None of the pigs displayed obvious signs of toxicity during the study period. The highest concentrations of diphacinone were found in liver tissue. Cooking had little effect on residual diphacinone concentrations. The hazards to humans and pets from meat from feral pigs that consumed the rodenticide diphacinone are not reduced by cooking; consumption of pig meat obtained from areas with active rodent control programs should be avoided.

Determination of Acetaminophen Residues in Whole Body Brown Treesnakes

Abstract Acetaminophen was extracted from brown treesnakes (Boiga irregularis) and analyzed by reversed‐phase high‐performance liquid chromatography (HPLC). Acetaminophen was quantified by UV absorbance at 250 nm. Recoveries were determined by analyzing acetaminophen‐fortified blank homogenized tissue. The mean recovery of acetaminophen in whole body brown treesnakes was 87.9% ± 5.9% and 92.2% ± 5.8% for the fortification levels of 20 and 2400 µg/g, respectively. The methods limit of detection (MLOD) with UV detection was 0.70 µg/g.

LIQUID CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF ANTHRAQUINONE RESIDUES IN WEATHERED AND UNWEATHERED FORMULATED RICE SEED AND SURFACE WATER IN RICE FIELDS

Anthraquinone was extracted from weathered and non-weathered formulated rice seed and analyzed by reversed-phase high performance liquid chromatography. Anthraquinone was quantified by UV absorbance at 325 nm. Recovery data were determined by analyzing anthraquinone fortified control rice seed. The mean recovery of anthraquinone in rice seed was 99.3 ± 0.5% for the range of 0.050 to 1.00% anthraquinone. Anthraquinone residues in surface water samples from rice fields were determined by direct injection of filtered samples into a reversed-phase high performance liquid chromatograph and quantified by UV absorbance at 254 nm. Recovery data were produced by analyzing anthraquinone fortified control surface water samples from rice fields. The mean recovery of anthraquinone in surface water samples was 97.0 ± 2.4% for the range of 8.0 to 400 ng/mL anthraquinone.

Determination of Sulfadimethoxine Residues in Skunk Serum by HPLC

Abstract Sulfadimethoxine (SDM) was extracted from skunk serum and isolated by reversed‐phase high performance liquid chromatography. SDM was detected by ultra‐violet absorbance at 270 nm and quantified by comparison to an external calibration standard. Recovery data were determined by analyzing SDM fortified control serum. The overall mean recovery with relative standard deviations of SDM in fortified skunk serum samples was 99±7%. The recovery for 0.38, 5.2, and 14.2 µg/mL SDM was 96.0±7.5%, 102±6.1%, and 97.3±5.1%, respectively. The method limit of detection for SDM in skunk serum ranged from 0.032 to 0.057 µg/mL SDM with a mean value of 0.040 µg/mL SDM. The method reported is much simpler and equally efficient as previous methods developed for the determination of SDM residues in serum.

Response of Captive Skunks to Microencapsulated Tetracycline

A captive striped skunk (Mephitis mephitis) study was conducted between February and June 2004 at the United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services National Wildlife Research Center, Fort Collins, Colorado, USA. The main objective was to determine the percentage of adult striped skunks that were marked after consuming placebo oral rabies vaccine (ORV) baits containing 100 mg of an experimental microencapsulated (coated microparticle) tetracycline hydrochloride biomarker. Biomarkers were identified in the canine teeth and mandibles of five of five skunks that consumed an ORV bait. A second objective was to determine if the microencapsulated tetracycline was resistant to photochemical conversion from tetracycline to epitetracycline. After 15 days of exposure, conversion from tetracycline to epitetracycline concentration in the microencapsulated product (mean 1.9% conversion, SD=1.24) was significantly less (P=0.006) than the pure-grade tetracycline powder (mean 7.5% conversion, SD=1.37). Results support the use of microencapsulated tetracycline hydrochloride as a biomarker in circumstances where the use of conventional powdered tetracycline hydrochloride is not feasible due to ORV bait design constraints.