The susceptibility of the Indian field mouse,Mus booduga gray,to anticoagulant rodenticidal baits

The baseline susceptibility of the Indian field mouse, Mus booduga was established for warfarin, bromadiolone and brodifacoum by means of nochoice feeding tests. The mice were found to be more susceptible to the second generation anticoagulants bromadiolone (0.005 g kg^?1) and brodifacoum (0.002 g kg^?1) than warfarin (0-25 g kg^?1). They required 8–10 days feeding on warfarin (0.25 g kg^?1) diet for complete mortality. A feeding period of 8 days corresponding to 99% mortality was suggested as a checking test for registering future warfarin resistance in suspect samples of M. booduga.     

Field evaluation of capsaicin as a rodent aversion agent for poultry feed

Developing additional techniques for reducing animal feed contamination by rodents and controlling rodent populations is critical to efforts aimed at reducing the occurrence of Salmonella spp infection on poultry farms. Capsaicin, a compound found in chili peppers of the genus Capsicum, produces a burning sensation in the mouth of mammals and is used effectively as an animal deterrent for some pest species. Applied to poultry feed, capsaicin may be effective as an aversive agent to deter rodent feeding and enhance acceptability of rodenticide baits. We tested capsaicin-treated poultry diets (2000 and 3000 Scoville Heat Units, SHU) in no-choice feeding trials at four active New York farms in the winter of 1997-1998. At all farms, consumption of the 2000 SHU diet by rodents (Norway rats, Rattus norvegicus (Berk), and house mice, Mus musculus L) was significantly less than consumption of a control diet. Consumption of the 3000 SHU diet by rodents was significantly less than consumption of a control diet at three of the four farms. Overall, consumption of treated diets was 58-97% and 55-98% less than consumption of the control diet, for the 2000 and 3000 SHU diets, respectively. These reductions appeared to be related closely to the availability of alternative feed sources at these farms. Two-choice feeding trials involving a rodenticide bait (0.05 g kg(-1) brodifacoum) and the 3000 SHU diet demonstrated that Norway rats preferred the rodenticide to the capsaicin-treated poultry feed. Overall, rodenticide bait acceptance was high (95.6%) when offered simultaneously with capsaicin-treated poultry feed. Although poultry managers must utilize several techniques to manage rodent pests, the use of capsaicin-treated diets to reduce feed losses and increase rodenticide bait acceptance appears promising. Use of capsaicin-treated feed on poultry farms may substantially reduce feed contamination by rodents and ultimately the incidence of Salmonella infection in poultry.     

The influence of anticoagulant resistance on effective rodent control in the UK1

Widespread use of warfarin, and other multiple-dose anticoagulants, selected populations of warfarin-resistant rodents in the UK and in other countries. The effectiveness of rodent control was dramatically reduced when the resistant animals formed a large proportion of a population. The second-generation anticoagulants were developed to overcome these practical control problems with warfarin and were considered to be effective rodenticides against warfarin-resistant populations. In the UK, however, difenacoum showed reduced efficacy for controlling an established warfarin-resistant Rattus norvegicus population covering a substantial area of farmland in southern England. Continued use of difenacoum selected for difenacoum-resistant animals, so that the rodenticide is now ineffective for controlling rats in three counties. Brodifacoum was subsequently used to control some infestations and there is evidence that these treatments selected for animals with an increased level of resistance to brodifacoum. Anticoagulant resistance in Mus domesticus is less of a practical problem because of the availability of non-anticoagulant rodenticides for the control of this species. There is evidence, however, of bromadiolone resistance in M. domesticus trapped on farms in the UK. Recent investigations of the mechanism of anticoagulant resistance in R. norvegicus have indicated that vitamin K3 (menadione) is an antidote to anticoagulants in resistant animals. This form of the vitamin is included as a dietary supplement in poultry and pig food and would aid the survival, and therefore increase the selection, of resistant animals when anticoagulants are used exclusively.     

Brodifacoum is effective against Norway rats (Rattus norvegicus) in a tyrosine139cysteine focus of anticoagulant resistance in Westphalia,Germany

BACKGROUND: The tyrosine to cysteine amino acid substitution at location 139 of the vkorc1 protein (i.e. tyrosine139cysteine or Y139C) is the most widespread anticoagulant resistance mutation in Norway rats (Rattus norvegicus Berk.) in Europe. Field trials were conducted to determine the incidence of the Y139C mutation at two rat‐infested farms in Westphalia, Germany, and to estimate the practical efficacy against them of applications, using a pulsed baiting treatment regime, of a proprietary bait (Klerat^?) containing 0.005% brodifacoum. RESULTS: DNA analysis for the Y139C mutation showed that resistant rats were prevalent at the two farms, with an incidence of 80.0 and 78.6% respectively. Applications of brodifacoum bait achieved results of 99.2 and 100.0% control at the two farms, when measured by census baiting, although the treatment was somewhat prolonged at one site, possibly owing to the abundance of attractive alternative food. CONCLUSION: The study showed that 0.005% brodifacoum bait is fully effective against Norway rats possessing the Y139C mutation at the Münsterland focus and is likely to be so elsewhere in Europe where this mutation is found. The pulsed baiting regime reduced to relatively low levels the quantity of bait required to control these two substantial resistant Norway rat infestations. Previous studies had shown much larger quantities of bromadiolone and difenacoum baits used in largely ineffective treatments against Y139C resistant rats in the Münsterland. These results should be considered when making decisions about the use of anticoagulants against resistant Norway rats and their potential environmental impacts. Copyright © 2012 Society of Chemical Industry     

Revised methodology for a blood-clotting response test for identification of warfarin-resistant Norway rats (Rattus norvegicus)

A blood-clotting response test for warfarin resistance in Norway rats ( Rattus norvegicus ) was developed by our laboratory in the late 1970s, based on knowledge of biochemical mechanisms available at that time. That test used warfarin, its the free base which is not watersoluble, and vitamin K₁ 2,3-epoxide as an antidote for warfarin-resistant rats only. We have modified the above test to use a water-soluble salt of vitamin K₃ (1 mg kgg⁻¹ body weight), which is an antidote in a wider range of warfarin-resistant rat strains than vitamin K₁ 2,3- epoxide, and a water-soluble salt of warfarin (5.4 mg kg⁻¹ body weight). Sodium warfarin and vitamin K₃ are administered by oral gavage, and the blood-clotting response measured 24 h later. In a series of validation tests there were no significant differences between results obtained by either method. The new method, however, uses materials which are commercially available, and eliminates the possibility of misclassifying warfarin-resistant rats as susceptible because vitamin K₁ 2,3-epoxide was not an antidote in those strains. We also present evidence that measuring blood-clotting response to feeding on a vitamin K-free diet for 4 days is not a reliable method for determining the genotype of warfarin-resistant rats.     

Palatability of bird repellents to Rattus norvegicus

The palatability to captive, mostly laboratory-bred, Norway rats (Rattus norvegicus) of cereal-based baits containing 0.02 g kg-1 brodifacoum, with and without bird-repellent additives, was compared in a no-choice experimental design. Methyl anthranilate (25 g kg-1), dimethyl anthranilate (25 g kg-1) and cinnamamide (2.5 g kg-1) reduced bait consumption by the rats, but all except one rat ate enough bait to receive a lethal dose. Cinnamamide (1 g kg-1), ortho-aminoacetophenone (0.1 g kg-1) and tannic acid (20 g kg-1) did not reduce bait consumption and all rats died after eating baits. The concentration of cinnamamide palatable to rats has only a low and short-lived repellency to birds, so it does not warrant further investigation. However, ortho-aminoacetophenone and tannic acid should now be field-tested for palatability to all three rat species in New Zealand and for repellency to native New Zealand birds.     

Toxicity of brodifacoum to the rock hyrax,Procavia capensis

Rock hyraxes,Procavia capensis (Mammalia: Hyracoidea), were fed 0.005% brodifacoum in apple bait for 20 and 48 h in no-choice laboratory experiments. Death of three out of five animals took place (11-15 days after the feeding) after the consumption of 7.0-7.9 mg a.i./kg body weight in the 20-h feeding and in four out of four animals death occurred (6-9 days after the feeding) following the consumption of 5.7-15.4 mg/kg in the 48-h feeding.     

Pesticides

Abstract

The anticoagulant chlorophacinone was evaluated in the laboratory for the control of the gerbils Tatera indica Hardwicke and Meriones hurrianae (Jerdon), which are major pests of agricultural crops, grassland and reforestation projects in the arid zone of India. Millet and sorghum grain treated with chlorophacinone was offered in no‐choice feeding tests. The results showed that 100% mortality occurred after seven and five days with 0.0075% chlorophacinone and after three and four days with 0.01% chlorophacinone in T. indica and M. hurrianae respectively. The anticoagulant‐treated bait was significantly less palatable than untreated bait, except bait containing 0.0075% chlorophacinone to T. indica. It is concluded that 0.0075% chlorophacinone can be effectively used to control the gerbils, especially bait‐shy populations previously exposed to zinc phosphide bait. Chlorophacinone appears to give more effective control than warfarin and fumarin, and slightly less effective control than brodifacoum.     

Potentiation of warfarin toxicity to roof rats (Rattus rattus) by L-histidine and by vitamin K adsorbers

The efficacy of warfarin alone or with various additives was tested against roof rats (Rattus rattus). Warfarin alone at 50 mg kg^?1 of bait killed 37% of the roof rats where-as the additives, L -histidine (40 mg kg^?1 of bait), activated-clay, charcoal and carbon (10 g kg^?1 of bait), tested individually, produced no mortality. However, when warfarin wascombined with each of these additives in turn, only the L -histidine combination resulted in 100% mortality while the other combinations killed 88, 75 and 63% of the test rats respectively. Further trials of paired comparison tests were carried out in order to evaluate the efficacy of the warfarin/L -histidine combination under different environmental conditions. All the rats succumbed to this combination in both cage and rattery conditions when there was no alternative food. Mortality decreased to 60% in cage and 70% in rattery when alternative food was provided alongside the poison bait. Rats tended to die more quickly with the L -histidine combination than with warfarin alone. Field trials also confirmed that this combination was effective in reducing roof rat infestations as shown by the yield of corpses, the post-poison bait intake and post-operational surveillance.     

A review of biochemical mechanisms of warfarin resistance in the house mouse

The biochemical mechanisms of warfarin resistance in the house mouse (Mus musculus L.) have not been fully investigated. In some populations of warfarin-resistant mice there is a reduction in sensitivity of hepatic vitamin K-epoxide reductase to inhibition by warfarin. This is similar to a proposed mechanism of anticoagulant resistance in the Norway rat (Rattus norvegicus Berk.). The same enzyme in other warfarin-resistant populations is, however, sensitive to warfarin inhibition. Other studies have indicated that detoxification may play a role in conferring warfarin resistance in house mice.     

Tenth international congress of plant protection,Brighton, November 1983

Abstract

Field trials were conducted to control rodent pests of wheat crop by improving bait acceptability through taste enhancers (additives). Egg shell, egg yolk, yeast, minced meat, sheep blood and chicken blood were mixed 2% by weight individually in a bait base of broken rice and wheat flour. Brodifacoum and bromadiolone bait with egg shell additive ranked first, and egg yolk second, in preference over other additive poison baits and poison bait without additive. Poison baiting yielded 93.3% and 86.7% reduction in rodent population with brodifacoum and bromadiolone (0.005% each), respectively. Three baitings, at tillering, flowering and maturity stage of the crop, gave 91.0% tiller damage reduction with brodifacoum and 86.0% with bromadiolone as compared to control (untreated). It is concluded that three poison baitings containing egg shell additive should be initiated at tillering stage followed by flowering and maturity of the wheat crop for increased yield.     

Assessing insecticide resistance and aversion to methomyl-treated toxic baits in Musca domestica L (Diptera: Muscidae) populations in southern California

Progeny of house flies (Musca domestica L) from ten California poultry operations, three dairies and one horse-riding facility were tested for methomyl- and muscalure-treated bait resistance using up to three different assays: a topical assay, a no-choice feeding assay and a choice feeding assay. LD50 resistance factors from the topical assay, compared with a locally-derived susceptible colony, ranged between 1 and 4. LC50 resistance factors from the no-choice feeding assay ranged mostly between 2 and 5, with one value of 18. Measurable LT50 resistance ratios for female flies in the choice feeding assay ranged from 43 to 159; two populations had <10% mortality at 48h and could not be measured. LT50 resistance ratios for male flies in the choice feeding assay ranged from 26 to 96, and one population was too resistant to measure. A behavioral assay tested the feeding preference of male and female flies provided a dish of sugar and a dish of methomyl- and muscalure-treated bait. Of eight strains tested, females from seven strains and males from six strains showed significant preference for sugar over bait. Behavioral factors appear to be important in the severe resistance of house flies to baits in California.     

Performance studies with the new anticoagulant rodenticide,flocoumafen, against Mus domesticus and Rattus norvegicus1

Flocoumafen is a new, highly potent anticoagulant rodenticide from Shell Research. It is effective against all the economically important species tested to date, including those with warfarin-resistant strains. This paper is concerned with its performance against two important commensal rodent species, Mus domesticus and Rattus norvegicus. In laboratory studies these two pest species may absorb a lethal dose of flocoumafen by taking a 0.005% (50 ppm) bait as part of their food intake on only one occasion. This single-feed potency of flocoumafen, combined with its good intrinsic palatability, makes it ideal for use in pulse baiting. Marketed under the Shell trade mark Storm, the principal bait formulation selected for commercialization is the wax-bound block. Recent advances in formulation development include increased resistance to attack by insects and fungi and the incorporation of a bitter taste which acts as a deterrent for humans without influencing the palatability of the bait to rodents. Flocoumafen's outstanding potency has been confirmed in a wide range of field trials. In the UK alone, almost 70 pen and field trials have been successfully completed with a mean estimated control in excess of 95%.     

Toxicity of calciferol,warfarin and their combinations to Rattus norvegicus (albino) and R. rattus

The response of Rattus norvegicus and R. rattus to calciferol, warfarin and a combination of these compounds was tested. Both species succumbed to the recommended bait concentrations of calciferol (1000 mg/kg) and warfarin (250 mg/kg) when tested individually. However, R. rattus was more susceptible to lower concentrations of calciferol (500 and 750 mg/kg) as compared to R. norvegicus, which was sensitive to lower concentrations of warfarin (12.5 and 25 mg/kg bait). Addition of calciferol at different concentrations did not affect the toxicity of warfarin against R. norvegicus. However, with R. rattus calciferol (250–350 mg/kg) or warfarin (50 mg/kg bait), which individually produced partial mortality, in combination produced a complete kill besides accelerating death. Combination of higher dosages of calciferol with warfarin (1000 + 250 mg/kg bait) tested against both species showed no advantages, resulting in neither lower bait consumption nor speedier death, though individually the components gave complete kills.     

The genetic mechanisms of warfarin resistance in Rattus rattus found in the wild in Japan

Warfarin is commonly used worldwide as a rodenticide. It inhibits blood coagulation by inhibiting vitamin K 2,3-epoxide reductase (VKOR) activity leading to hemorrhage. However, it has been reported that repeated or long-term treatment with warfarin results in resistance emerging in wild rodents. Such resistance may explain why it is difficult to control rodents in many regions in Japan. In this report, we studied mutations in the VKOR gene (including the VKOR complex subunit 1 (VKORC1)), while also analyzing VKOR and clotting factor activity in black rats (Rattus rattus) in order to understand better the mechanism of warfarin resistance in this species.We sequenced the VKORC1 gene from 275 rats living in the wild in Japan. We found several types of novel base substitutions, some of which conferred warfarin resistance.There was no difference in coagulation times between warfarin-sensitive and resistant rats measured under physiological conditions. However, after warfarin administration, no effect was noted in warfarin-resistant rats, although a prolonged coagulation time was noted in warfarin-sensitive rats.We also determined the kinetic differences in hepatic microsomal VKOR-dependent activity between warfarin-resistant and sensitive rats. Warfarin-resistant rats showed 2-3-fold lower V_max/K_m values than did sensitive rats. In addition, we report that resistant rats found in the Tokyo area had a VKOR activity which was poorly inhibited by warfarin.Finally, we conclude that reduced VKOR activity and warfarin resistance in the Japanese black rat might be due to mutations in the VKORC1 gene. However, further study is needed to clarify how such rats can maintain adequate vitamin K-dependent clotting factor levels, while simultaneously exhibiting low VKOR activity and warfarin resistance.     

Bromadiolone,a New Anticoagulant Rodenticide1

A search for more effective anticoagulant rodenticides has brought about the development of a new compound, coded LM-637, and temporarily named bromadiolone. Results of efficacy tests on 10 rodent species are discussed in detail. The compound was found to be a very potent and highly palatable anticoagulant which is capable of achieving 100% mortality in Norway rats, Rattus norvegicus (Berkenhout), with 1-day feeding. Efficacy was demonstrated on all 3 commensal rodents and several important agricultural rodent pests native to the United States. A relatively few feedings (1 to 5 days) of bait containing 0.005 % bromadiolone produced death in most species tested. These rodenticidal properties make bromadiolone a most promising control agent.     

防治稻田黄毛鼠和板齿鼠的试验

烟草霜霉病(Peronospora tabacina Adam)是烟草作物的一种毁灭性病害,蔓延很广,遍及世界许多国家。鉴于我国无烟草霜霉病分布,因此,杜绝此病的传入,保护烟草生产,对来自疫区的烟叶实施检疫很有必要。烟草霜霉病传病的主要来源是分生孢子和卵孢子,但分生孢子与卵孢子比较,其抗逆能力差,寿命短,烟叶经晒干、贮藏、航运、加工等过程,随烟叶携带霜霉病分生孢子传病的可能性少。关于卵孢子,尽管萌发的具体情况不甚清楚,传播流行所起作用认     

3种抗凝血类杀鼠剂在喀什农区防治害鼠效果及对家禽的安全性评价

为确定适于防治南疆农区鼠害的抗凝血类杀鼠剂, 在喀什地区疏勒县采用夹捕法、食饵法、粉迹法评估了杀鼠醚、溴敌隆、溴鼠灵的防治效果, 并采用灌胃法给药测试3种杀鼠剂对家鸡Gallus domestiaus和鸽子Columba livia的安全性。结果表明, 连续投放毒饵10 d后, 与溴敌隆防治区相比, 杀鼠醚防治区的阳性粉块和无毒小麦取食量的下降幅度均无显著差异, 但无毒小麦取食量下降的农户比例更高;且防治后褐家鼠比例更低, 防治期间毒饵消耗量更高。连续单独投放溴敌隆30 d的灭鼠效果可达90.9%, 但10 d溴敌隆与20 d溴鼠灵联合防治防效仅为65.9%。灌胃法测试表明, 对当地家禽类的毒性从低到高依次为杀鼠醚、溴敌隆和溴鼠灵。因此, 建议优选毒性较低的杀鼠醚或溴敌隆用于南疆农区鼠害防治。     

The toxicity of brodifacoum wheat bait to the field rodents Microtus guentheri and Meriones tristrami

The toxicity of the anticoagulant brodifacoum to the field rodent species Microtus guentheri (Danford & Alston) and Meriones tristrami Thomas was tested in the laboratory. Brodifacoum 0.05 g kg^?1 whole-wheat bait was offered to the animals without additional food. The LD₅₀ calculated for M. guentheri was 2.28 mg kg^?1 body weight. Brodifacoum was found to be more toxic to M. tristrami; the LD₅₀ was c. 0.8–0.9 mg kg^?1 body weight. The toxicity data served to plan the doses of bait to be broadcast in the field.     

The efficacy of two permanent poison-baiting measures against Mus domesticus living in farm buildings in the UK1

The effectiveness of two poison bait formulations was examined in trials against infestations of Mus domesticus in farm buildings. Treatment was extensive on each of four farms, covering all buildings and lasting 1 year. In the four trials, bait containing calciferol and warfarin in combination, or difenacoum was used. Mouse infestation level was monitored, using the mark-recapture trapping technique, before poison-baiting was begun and every 6 weeks thereafter. Poison bait consumption was high initially and mouse numbers were substantially reduced on all four farms within 6 weeks. Subsequently, the difenacoum treatments were the most effective in keeping infestation levels extremely low. Mice still resident when the treatments were terminated were removed by live and kill traps. Laboratory feeding tests were conducted on the live-caught survivors; all animals died after consuming poison bait of the kind used in the trials. Additional live-trapping, 6 months and 1 year later, produced evidence of recolonization and of renewed population growth. It is concluded that sustained control effort is needed to prevent the build-up of M. domesticus numbers in farm buildings.