Large-scale identification of rodenticide resistance in Rattus norvegicus and Mus musculus in the Netherlands based on Vkorc1 codon 139 mutations

BACKGROUND

Resistance to rodenticides has been reported globally and poses a considerable problem for efficacy in pest control. The most-documented resistance to rodenticides in commensal rodents is associated with mutations in the Vkorc1 gene, in particular in codon 139. Resistance to anticoagulant rodenticides has been reported in the Netherlands since 1989. A study from 2013 showed that 25% of 169 Norway rats (Rattus norvegicus) had a mutation at codon 139 of the Vkorc1 gene. To gain insight in the current status of rodenticide resistance amongst R. norvegicus and house mice Mus musculus in the Netherlands, we tested these rodents for mutations in codon 139 of the Vkorc1 gene. In addition, we collected data from pest controllers on their use of rodenticides and experience with rodenticide resistance.

RESULTS

A total of 1801 rodent samples were collected throughout the country consisting of 1404 R. norvegicus and 397 M. musculus. In total, 15% of R. norvegicus [95% confidence interval (CI): 13–17%] and 38% of M. musculus (95% CI: 33–43%) carried a genetic mutation at codon 139 of the Vkorc1 gene.

CONCLUSION

This study demonstrates genetic mutations at codon 139 of the Vkorc1 gene in M. musculus in the Netherlands. Resistance to anticoagulant rodenticides is present in R. norvegicus and M. musculus in multiple regions in the Netherlands. The results of this comprehensive study provide a baseline and facilitate trend analyses of Vkorc1 codon 139 mutations and evaluation of integrated pest management (IPM) strategies as these are enrolled in the Netherlands. © 2022 The Dutch Pest and Wildlife. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Monitoring the Exposure of Barn Owls to Second-Generation Rodenticides in Southern Eire

In an extensive field study conducted over five counties in southern Eire during the winter of 1988–89, 19 Barn Owl (Tyto alba) roosts and/or nests were located. The local farmers and landowners within about a one-mile radius of the Barn Owl sites were surveyed concerning their use of rodenticides and observations of any secondary rodenticide toxicity effects. Regurgitated owl pellets were collected: (a) for dissection and prey analysis, and (b) for chemical analysis to determine residues of the second-generation rodenticides, brodifacoum, difenacoum and flocoumafen. Most farmers interviewed used rodenticide baits (73%), and almost all (92%) stated that they took precautions to protect domestic and wild non-target animals. The four rodent species, brown rat, wood mouse, house mouse and bank vole provided 83% of the Barn Owl diet, and birds contributed another 12%. At least 97% of the 89 pellets analysed contained less than the limit of determination of the three second-generation rodenticides, 0·01–0·02 mg kg⁻¹ of each isomer. Apparent residues in the remainder were likely to be the result of interference from co-extracted material. These results indicated that during the monitoring period, none of the owls studied was exposed to significant residues of these rodenticides in their prey.     

The control of commensal rodents in Britain1

Rattus norvegicus and Mus domesticus are the only significant commensal rodents in Britain, though Rattus rattus is also present in a few places. R. norvegicus is by far the most important pest of agriculture. No recent quantitative information is available on the status of rodent infestation, damage or control, though these are generally considered to be satisfactory and to have altered little in the last few years. In particular, there seem to be no infestation problems of practical significance that cannot be adequately resolved by currently available control techniques. Recent developments of practical interest include the occurrence of rodent damage to the plastic bags in which big bale silage is preserved, low-grade resistance to difenacoum in R. norvegicus in one locality, and the continued introduction of improved rodenticides. New legislation has been introduced giving government comprehensive powers over the use of pesticides, under which rodenticides must now be assessed for safety, efficacy and humaneness. Responsibility for research, training and extension in rodent control has largely been devolved to the private, academic and local government sectors, with central government now undertaking these activities only on a commercial basis. The nature and significance of these changes is discussed.     

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.     

华北平原旱作区农田害鼠化学防治技术的优化筛选研究

作者研究了不同投饵方式,不同灭鼠季节和不同杀鼠剂的农田灭鼠效果,并研究了溴代毒鼠磷和磷化锌不同浓度与不同投饵量对农田害鼠的灭杀率,筛选出了农田灭鼠优化技术:封锁带式投饵,0.5%溴代毒鼠磷小麦毒饵每堆投饵2克,全年中灭鼠适期为3—4月份。这套优化灭鼠技术较从前采用的灭鼠技术提高了灭效,而且大幅度降低了灭鼠成本。     

华北平原旱作区农田害鼠化学防治技术的优化筛选研究

作者研究了不同投饵方式,不同灭鼠季节和不同杀鼠剂的农田灭鼠效果,并研究了溴代毒鼠磷和磷化锌不同浓度与不同投饵量对农田害鼠的灭杀率,筛选出了农田灭鼠优化技术:封锁带式投饵,0.5%溴代毒鼠磷小麦毒饵每堆投饵2克,全年中灭鼠适期为3-4月份。这套优化灭鼠技术较从前采用的灭鼠技术提高了灭效,而且大幅度降低了灭鼠成本。     

Ecological and Toxicological Bases of Directed Control of Arvicola terrestris (L.) and Microtus arvalis (Pallas) in Agricultural Crops 1

In order to protect crops during outbreaks of Arvicola terrestris (L.) or Microtus arvalis (Pallas), it is necessary to have formulations with acute action and high rodenticidal potential; rodenticides should be applied as baits corresponding to the hygrotrophic specialization of the species. When compared with zinc phosphide, Gliftor provides reliable control of voles in any season. The outlook of bactorodencide (bacterial preparation) applications is being determined with particular reference to their ecological effects.     

Effects of physical barriers and eradication on recolonization of rodents in poultry farms

Abstract

Mus musculus, Rattus rattus and Rattus norvegicus are pests in poultry farms, causing economic losses and transmitting diseases. Control is commonly conducted through anticoagulant rodenticides, but this control is not effective through time. We aimed to assess the effect of rodent exclosure on long-term success of rodent control in poultry farms of the pampean region, Argentina, and to evaluate indirect estimators of rodent abundance. In both exclosure and non-exclosure sheds rodent abundance decreased significantly after eradication but mice populations showed a recovery, suggesting that the eradication was not complete. Rats did not recover, but the low abundance found at the beginning of the experiment does not allow an accurate conclusion.     

The control of mole,water vole and muskrat with phosphine1

The number of rodenticides for control of outdoor rodents and the number of uses of the remaining products is declining. Phosphine is valued highly because it causes no secondary poisoning and is considered to be environmentally safe. Although it has been used against mole (Talpa europaea) and water vole (Arvicola terrestris) in some countries for decades, in other countries a breakthrough is more recent. The development of a new formulation, generating phosphine rapidly, may also contribute to a wider use. In the Netherlands investigations have been undertaken on the mode of application against mole and water vole. Experiments against muskrats (Ondathra zibethicus) show promising results. The use of phosphine against this rodent could save on labour considerably, when compared to trapping.     

An efficacy test of cholecalciferol plus diphacinone rodenticide baits for California voles (Microtus californicus Peale) to replace ineffective chlorophacinone baits

California voles cause damage to pastures and rangelands, orchards and nurseries, and a wide variety of field crops, including artichokes. The anticoagulant rodenticides (chlorophacinone and diphacinone) typically used for voles are becoming less effective in controlling their populations. Consequently, there is a need to identify new rodenticides that will have a high efficacy on California voles so that agricultural production losses to rodents can be substantially reduced. We tested a new formulation containing two active ingredients (cholecalciferol and diphacinone) as a control method for California voles. Both a pelleted bait and an oil-coated artichoke bract bait were very palatable and efficacious against wild-caught, captive California voles. Efficacy levels of 70%–80% were achieved in the two-choice feeding trials. Additionally, the days-to-death (5–6 days) were less than the time-to-death with anticoagulant only baits. We recommend that a field efficacy study be conducted with cholecalciferol plus diphacinone bait formulations to determine their field performance in the reduction of agricultural damage by California voles.     

Distribution of VKORC1 single nucleotide polymorphism in wild Rattus norvegicus in France

BACKGROUND: Anticoagulant rodenticides are commonly used to control rodent pests all over the world. These pesticides inhibit one enzyme of the vitamin K cycle, Vkorc1, and thus prevent blood clotting and cause death by haemorrhage. Resistance to anticoagulants was first observed in Scotland in 1958, and more potent anticoagulants have been developed to overcome this obstacle. Unfortunately, these chemicals are very toxic and cannot be used everywhere. Some authors have shown that resistance to anticoagulants seems closely linked with single nucleotide polymorphism (SNP) in the Vkorc1 gene. RESULTS: This study draws a map of SNP and haplotypes found in Vkorc1 in rats from different areas of France. Some of them had never been described before. Moreover, the Y139F mutation, described previously in France and Belgium, is the most frequent in France. This mutation is known to be associated with a strong resistance to anticoagulants, and it was found in 28% of the samples. CONCLUSION: This biomolecular approach to studying and detecting resistance is easier to carry out than the phenotypic approach measuring blood coagulation time because it can be conducted on biological samples from dead animals, and it is less dangerous for the operator. Copyright © 2009 Society of Chemical Industry     

From biology to management of Savi's pine vole (Microtus savii)

Savi's pine vole (Microtus savii) is a rodent species of the Cricetidae family, inhabiting southern European agroecosystems. It is considered to be the main cause of rodent‐attributed damage in Italy. To achieve an effective management, detailed knowledge of this species is needed. However, the available information about this species is fragmentary and incomplete. In this paper, the existing knowledge of Savi's pine vole taxonomy, reproduction, population dynamics, habitat and food preferences is reviewed in order to organise available information and identify priority areas of future research. Some of the changes in farming practices that have occurred in recent decades may have increased the impact of Savi's pine vole populations in crop fields. To manage this pest species effectively, an integrated strategy is recommended (involving habitat management, trapping and, when appropriate, the use of rodenticides). The apparent lack of cyclical population outbreaks and the relatively small litter size and long gestation and interpartum period of this species suggest that it could be more manageable than other vole species, while its strict herbivorous diet, stable population size in open habitats and wide distribution seem to indicate it as an ideal model species for risk assessment studies. © 2015 Society of Chemical Industry     

The toxicity of three second-generation rodenticides to Barn Owls

The toxicity of three second-generation rodenticides to Barn Owls (Tyto alba Scop.) has been investigated. Brodifacoum, difenacoum and flocoumafen were separately fed to owls over a period of 15 days via rodenticide-fed mice to simulate the potential route of exposure in the wild. The owls survived a cumulative dose of each rodenticide of at least 1.9 mg kg^?1 owl body weight over 15 days. This is equivalent to the consumption of two 25 g mice with a rodenticide residue of 1 mg kg^?1 each day for 15 days. Residue analysis confirmed that the liver is the organ which retains the largest residue of ingested rodenticide.     

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.     

Anticoagulant resistance in Europe: Appraisal of the data from the 1992 EPPO questionnaire

Resistance to the first successful anticoagulant rodenticide, warfarin, was detected in the Norway rat (Rattus norvegicus Berk.) in 1958, and it has since expanded to cover other commensal rodent species (R. rattus L., Mus musculus L.) and the majority of later-developed anticoagulant compounds. The purpose of this paper is to give an up-to-date picture of the current distribution of anticoagulant resistance in Europe, as revealed by the questionnaire dispatched by EPPO (European and Mediterranean Plant Protection Organization) to its member countries in 1992. Replies were received from 13 countries (43% of EPPO members), and it was found that broad-spectrum resistance occurred in practically all those countries that reported testing activity. A likely conclusion based on this finding is that true distribution of resistance is certainly more extensive than documented by the questionnaire replies. Another conclusion drawn by the EPPO Rodent Control Panel was that the existing resistance detection protocols were no longer adequate to cover the whole array of existing anticoagulant rodenticides. Consequently, a new guideline including novel methods particularly for detecting resistance to single-dose anticoagulant compounds was urgently needed. This guideline is currently under review.     

European Field Voles of the Genus Pitymys McMurtrie and their Damage in Agriculture,Horticulture and Forestry1

Research has been carried out to establish the actual incidence in European agriculture and forestry of damage by voles belonging to the genus Pitymys McMurtrie. Unfortunately, the great uncertainty remaining in the taxonomy of these voles and the practical difficulty of recognizing the species responsible for specific damage do not allow us to form, as yet, a complete picture of the situation. Nevertheless, it has been shown that, in Europe, Pitymys voles which are responsible for damage to agricultural crops (irregularly and with varying intensities) can, essentially, be placed in one of the following fundamental species groups:subterruneus (de Sélys Longcharnps), savii (de Séys Longchamps) or duodecimcostutus (de Sélys Longchamps). Without doubt, greatest damage appears to be done by voles of the species group savii which, in a decidedly more southern distribution area, brings about serious damage, particularly to horti-floricultural crops in the Italian peninsula. In Italy, where the Pitymys problem is perhaps more noticeable than anywhere else, the control methods used tend to be inefficacious and do not answer the problem. We hope, therefore, besides conducting a comprehensive biological study of this species group, to carry out adequate experimentation towards developing methods for testing the latest rodenticides as to their efficacy against Pitymys and to develop an adequate application technique.     

Resistance to anticoagulants in rodents

The present status of anticoagulant-resistant populations of Rattus norvegicus and Mus musculus in Britain is elaborated and special reference is made to evidence of the practical consequences of resistance for rodent control. A short review is given of genetical and toxicological aspects of resistance and it is predicted that continued dependence upon the anticoagulant rodenticides will lead to the development of new resistance problems. The failure of schemes for the eradication or containment of resistant rat populations by local use of alternative rodenticides is discussed and an approach based more soundly upon the principles of ecological genetics is indicated. It seems in practice, however, that the continued spread of resistance to anticoagulants in Britain is now inevitable and that the development of improved alternative rodenticides will be necessary in order to avoid a decline in the standard of rodent control.     

Exploring drivers of the usage of anticoagulant rodenticides on UK farms

Anticoagulant rodenticides (ARs) are considered inhumane, show increasingly limited efficacy due to acquired resistance, and carry environmental consequences associated with non-target species uptake. In a questionnaire study of 499 UK farms that all deployed chemical rodenticide we found a high mean reliance (79%), on second generation ARs with just over half of the respondents using no other rodent control methods. Additional methods where deployed, alone or in combination, included predation (41%), kill-trap deployment (16%) and shooting (1%). Nearly 40% of all respondents deployed rodenticides year-round. There was no evidence to suggest that “tidy-farm” measures, such as clearing food spills and minimising on-farm rodent harbourage sites aimed at minimising rodent-associated problems, were associated with a lower likelihood of year-round deployment; in fact trends in our analyses suggested the opposite. We therefore encourage operators to fully evaluate the true necessity of rodenticide deployment before AR use.     

Non-invasive method for monitoring the exposure of Barn owls to second-generation rodenticides

Chemical analysis of rodenticide residues in regurgitated owl pellets has been shown to be a sensitive, non-invasive method for monitoring the potential exposure of Barn Owls to second-generation rodenticides in their prey. The method, originally developed for flocoumafen, has been extended to two other rodenticides. brodifacoum and difenacoum. The method was validated as part of a toxicity study in which Barn Owls were separately fed 40–130 μg day ^?1 of brodifacoum, difenacoum and flocoumafen in mice over 15 days. Each day an average of 25% of the consumed rodenticide was regurgitated in the pellets.     

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。