The effect of dextromethorphan in preventing cholecalciferol-induced poison shyness and sickness-induced anorexia in the laboratory Norway rat

BACKGROUND: Overcoming bait and poison shyness is critical to the success of pest control operations against rats and other rodents. The authors hypothesized that the N-methyl-D-aspartate receptor blocker, dextromethorphan, could prevent the acquired memory of sickness and sickness-induced anorexia resulting from rodents eating poisoned bait. RESULTS: Cholecalciferol (1/4 LD(50)) was mixed with dextromethorphan and fed to rats on two 2 day sessions, with an 18 day break in between. Dextromethorphan did not prevent poison shyness; during the second poisoning period, both the cholecalciferol only and the cholecalciferol plus dextromethorphan groups had lower intakes of the bait compared with the control and dextromethorphan only groups. In addition to the previously recorded symptoms of cholecalciferol poisoning, the rats in this trial were observed to have nose bleeds, weepy eyes, laboured breathing and, in the case of the cholecalciferol only treated group, a period of decreased water intake followed by a period of increased water intake. There was also a period of increased water intake in the cholecalciferol plus dextromethorphan group.CONCLUSION: Dextromethorphan failed to prevent poison shyness and the anorectic effect of cholecalciferol. However, it did reduce anorexia from 17 days in the cholecaliferol group to 8 days in the cholecalciferol plus dextromethorphan group.     

我国黄毛鼠研究进展

黄毛鼠Rattus losea 是分布在中国长江以南地区以及东南亚地区的重要农田害鼠。该鼠栖息地广, 食性杂, 盗食各种农作物, 还是某些疾病的宿主和传播者。本文从形态特征、种群遗传学、生物学特性、种群生态学、抗药性、防治技术等方面详细介绍了黄毛鼠的研究进展。并根据目前的研究现状和存在问题, 提出建立基于精准预测预报, 研发生态优先、环境友好的防控新技术、新产品为核心的综合防控技术体系, 以期为黄毛鼠的可持续治理提供参考。     

珠江三角洲地区黄毛鼠抗药性的发生趋势及其Vkorc1基因多态性

为阐明珠江三角洲地区黄毛鼠Rattus losea对第1代抗凝血灭鼠剂的抗性发生趋势及其遗传机制,以杀鼠灵为标准药物,采用致死期食毒法对2017—2021年在广东省江门市捕获的165只黄毛鼠进行生理抗性检测,并测定每只试鼠的维生素K环氧化物还原酶复合物亚单位1(vitamin K epoxide reductase complex subunit 1,Vkorc1)的编码基因序列,分析其突变情况。结果显示,江门市黄毛鼠对第1代抗凝血灭鼠剂杀鼠灵的抗性率为27.03%～50.00%,在黄毛鼠Vkorc1基因中检测到6个不同的突变位点,包括2个错义突变位点Arg58Gly及Tyr139Cys和4个沉默突变位点Ala41Ala、Cys96Cys、Arg98Arg及Ala143Ala,突变率分别为87.27%、0.61%、1.21%、0.61%、1.21%和0.61%,其中Ala143Ala是在黄毛鼠中新发现的沉默突变位点。表明珠江三角洲地区黄毛鼠已对第1代抗凝血灭鼠剂产生了群体抗性并呈上升趋势,第58位的精氨酸突变成甘氨酸(Arg58Gly)是黄毛鼠抗性基因Vkorc1的主要突变位点。     

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     

黄毛鼠对第一代抗凝血灭鼠剂的抗药性监测

为明确黄毛鼠的抗药性发生状况,采用无选择性摄食试验法测定广东省不同类型区黄毛鼠的抗药性。结果表明:在频繁使用第一代抗凝血灭鼠剂的地区,黄毛鼠已产生了抗药性种群,其中江门市新会区和佛山市高明区的抗性率分别为36.67%和16.67%;中等用量地区的黄毛鼠产生了一定的抗药性,但尚未产生抗药性种群,如湛江市黄毛鼠的抗性率达到3.33%;而在低用量地区,未发现抗性鼠,但害鼠对药物的耐受力显著增强。为此,针对上述类型区黄毛鼠的抗药性状况提出了相应的鼠害持续控制对策。     

耿马县黄胸鼠发生规律与防控研究

1992-2008年,在云南省耿马县城区海拔1 100 m地区农田设置系统监测点,研究害鼠种类及发生消长规律。结果表明,农田害鼠以黄胸鼠为绝对优势种群,占17年所捕获害鼠总数的83%,近4年所捕害鼠全为黄胸鼠。年内捕获率和繁殖力出现双峰,与田间为害高峰相吻合。雌雄性比为1∶1.8,雄性多于雌性。以成体组捕获率最高,占总捕鼠数的50%;幼体组和亚成体组次之,分别占21%和20%。根据年内消长规律,确定化学统一灭鼠时间为4月中旬和10月底的干季。宜选用敌鼠、溴敌隆、氯鼠酮、氟鼠灵等,以稻谷作饵料为好。     

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.     

The impact of resistance on the use of second-generation anticoagulants against rats on farms in Southern England

Resistance amongst rats to second-generation anticoagulants, notably difenacoum, has been recognised since the 1970s. Although initially considered to be of practical significance, doubts were subsequently expressed that the degree of resistance was sufficient to explain ineffective rodenticide treatments. Research published elsewhere demonstrated the overriding importance of poor poisoned bait consumption, caused by the influence of certain ecological factors on rat behaviour, in reducing the effectiveness of second-generation anticoagulant treatments on farms in southern England. In this paper we consider, however, the subtle effects of resistance to anticoagulants on treatment outcome. The prevalence of resistance was increased amongst survivors of treatments and bait consumption by resistant survivors was higher than amongst susceptible survivors. The overall prevalence and degree of resistance to second-generation anticoagulants does not, however, currently represent a practical problem. Nevertheless, selection favouring increased resistance remains a long-term threat to the effectiveness of both difenacoum and bromadiolone.     

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.     

新疆南部农区鼠害调查与成因分析

南疆农区鼠害严重,但基础资料不足。为摸清当地鼠害发生特点,提供有效治理依据,本研究于2018年-2019年在南疆5地州39乡64村开展实地与问卷调查,并采用夹捕法调查害鼠种群构成。结果表明,南疆5地州农村普遍遭受鼠害影响,喀什与和田地区农田受害比例达89.4%,问卷结果表明农户和农田鼠害发生率均大于75%,且西部地区重于东部,约一半受访农户估计每年因鼠害损失超过500元。褐家鼠Rattus norvegicus是农户主要害鼠,占比超过70%;农田则以小家鼠Mus musculus和乌拉尔姬鼠Apodemus uralensis为主。这些结果表明,南疆农区鼠害处于重发态势,褐家鼠是主要鼠害来源,并有外来入侵风险。下一步应聚焦于监测主要害鼠种群动态规律,阐明褐家鼠来源和侵入机制,并探索建立适于当地的害鼠防治模式。     

褐家鼠种群动态初步研究

本文报道了1986—1993年贵州余庆县褐家鼠种群动态的研究结果。共解剖标本676只(雌353只,雄323只),对其雄鼠睾丸下降率,雌鼠怀孕率、胎仔数、繁殖指数的季节变化及年度差异和种群数量消长动态作了系统分析,研究期间平均怀孕率为22.03％,平均胎仔数为7.92只,繁殖指数为0.7321,每年1—3月和10—11月为两次妊娠高峰。确定了各年龄组的体重标准,研究了褐家鼠的肥满度。