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Rattus tiomanicus is a serious pest of oil palm plantations in Peninsular Malaysia, feeding on the ripening fruit. R. diardii is a rat of human habitations and has been only an occasional field species, presumably because it cannot compete with better adapted species. A widely used control for R. tiomanicus of proven effectiveness uses maize-based baits containing warfarin at 0.05% in 2 cm3 (14.5 g) wax-bound cubes. These are applied in campaigns at one per palm, replaced on 4 daily rounds, until acceptance has declined to 20%. This "standard method" is applied at about 6-month intervals, and rat populations remain low. In the early 1980s resistance to warfarin began in R. tiomanicus, and from about the same time R. diardii was found more often in oil palms, apparently in the same localities. This review is of studies of these phenomena. Rat population studies by mark, release, recapture (MRR) confirmed that warfarin baiting was failing against R. tiomanicus, or required prolonged application, whereas second-generation anticoagulants (brodifacoum, bromadiolone, and flocoumafen) were effective. Physiological resistance was confirmed in the laboratory. Direct substitution of second-generation compounds increased the cost of control considerably, and ways to reduce costs were investigated. Smaller bait size presented problems in monitoring bait acceptance, and longer intervals between replacements did not reduce consumption. Half the active ingredient concentration had some promise, but a first-round application of one bait per two palms was most practicable. Bromadiolone baits at 0.005% are now used at half density of one bait per two palms on the first application in areas of warfarin resistance. Where the problem was first noted, rat populations were compared in areas with and without continued baiting. In an 81-ha plot left unbaited, R. diardii gradually increased and replaced R. tiomanicus during 1982-84. R. diardii then remained predominant until 1989. In the baited plot, once bromadiolone was used (from early 1984) both species were controlled. It is postulated that R. diardii became able to out-compete R. tiomanicus because the genotype of the latter had somehow been weakened in the rapid selection for warfarin resistance.

The most common rodent control method worldwide is anticoagulant rodenticides (ARs), which cause death by internal bleeding. ARs can transfer to non-target predators via secondary exposure, i.e. by consuming contaminated rodents. Here we quantify the prevalence of seven AR substances in the liver tissues of altogether 17 mammalian or avian predator or scavenger species in Finland. In addition, we identify the environmental and biological factors potentially linked to secondary AR poisoning. No previous AR screenings have been conducted in the country, despite the widespread use of ARs and their potential impacts on the high levels of the ecosystem food chain. ARs were detected (≥0.3 μg/kg) in 82% of the 131 samples. The most prevalent and the AR with highest concentrations was bromadiolone (65% of samples). In 77% of the positive samples more than one (2–5) different ARs were detected. Of the environmental variables, we only found a weakly positive relationship between the coumatetralyl concentration and the livestock farm density. Conversely, overall AR concentration and number, as well as the concentration of three separate ARs (coumatetralyl, difenacoum and bromadiolone) differed among the three species groups tested, with the group “other mammals” (largely represented by red fox and raccoon dog) having higher values than the groups presented by mustelids or by birds. ARs are authorized only as biocides in Finland and a national strategy on risk management (e.g. for minimising secondary poisoning of non-target species) of ARs was adopted in 2011. Based on these results it appears that the risk mitigation measures (RMMs) either have not been followed or have not been effective in preventing wide scale secondary exposure. Continued monitoring of AR residues in non-target species is needed in order to evaluate the effectiveness of current RMMs and a need for new ones to reduce the risk of secondary poisoning. [ABSTRACT FROM AUTHOR]

Anti-blood coagulation rodenticides, such as warfarin, have been used all over the world. They inhibit vitamin K epoxide reductase (VKOR), which is necessary for producing several blood clotting factors. This inhibition by rodenticides results in lethal hemorrhage in rodents. However, heavy usage of these agents has led to the appearance of rodenticide-resistant rats. There are two major mechanisms underlying this resistance, i.e. , mutation of the target enzyme of warfarin, VKOR, and enhanced metabolism of warfarin. However, there have been few studies regarding the hepatic metabolism of warfarin, which should be related to resistance. To investigate warfarin metabolism in resistant rats, in situ liver perfusion of warfarin was performed with resistant black rats ( Rattus rattus ) from Tokyo, Japan. Liver perfusion is an in situ methodology that can reveal hepatic function specifically with natural composition of the liver. The results indicated enhanced hepatic warfarin hydroxylation activity compared with sensitive black rats. On the other hand, in an in vitro microsomal warfarin metabolism assay to investigate kinetic parameters of cytochrome P450, which plays a major role in warfarin hydroxylation, the V max of resistant rats was slightly but significantly higher compared to the results obtained in the in situ study. These results indicated that another factor like electron donators may also contribute to the enhanced metabolism in addition to high expression of cytochrome P450. [ABSTRACT FROM AUTHOR]

Anticoagulant rodenticides (ARs) are used worldwide to control populations of agricultural and urban rodents, but these pesticides may be accumulated in and poisoned non-target species of wildlife. Slugs may feed on rodenticide bait following field applications. Thus, it can be assumed that their predators are exposed to rodenticides through food chain transfer. However, AR exposure in the slugs has not been systematically studied. We investigated the accumulation of three ARs (chlorophacinone, bromadiolone or brodifacoum) in the slug Deroceras reticulatum exposed for a period of 5 days followed by depuration time of 4 days in the laboratory. Moreover, we studied the exposure of slugs to brodifacoum in the field. In the laboratory exposure, the slugs consumed rodenticide baits, but no mortality was observed. After 1 day, their concentrations were stable over the time and no differences were detected between the concentrations of the three ARs. After 5 days of exposure, mean concentrations in slugs were 1.71, 1.91 and 0.44 mg/kg wet weight for chlorophacinone, bromadiolone and brodifacoum respectively. A significant decrease of bromadiolone and brodifacoum in slugs was observed in the post exposure period. In the field study, brodifacoum was detected in > 90% of analyzed slugs after application of brodifacoum baits. Then, based on a toxicity-exposure ratio approach, we found that slug consumption may represent a risk of secondary poisoning for three of their predators under acute, repeated or subchronic exposure scenarios. These results suggest that the slugs are not only the potential subject to primary exposure, but also the source of secondary exposure for their predators following application of rodenticide baits. [ABSTRACT FROM AUTHOR]

Current reactive pest management methods have serious drawbacks such as the heavy reliance on chemicals, emerging genetic rodenticide resistance and high secondary exposure risks. Rodent control needs to be based on pest species ecology and ethology to facilitate the development of ecologically based rodent management (EBRM). An important aspect of EBRM is a strong understanding of rodent pest species ecology, behaviour and spatiotemporal factors. Gaining insight into the behaviour of pest species is a key aspect of EBRM. The landscape of fear (LOF) is a mapping of the spatial variation in the foraging cost arising from the risk of predation, and reflects the levels of fear a prey species perceives at different locations within its home range. In practice, the LOF maps habitat use as a result of perceived fear, which shows where bait or traps are most likely to be encountered and used by rodents. Several studies have linked perceived predation risk of foraging animals with quitting-harvest rates or giving-up densities (GUDs). GUDs have been used to reflect foraging behaviour strategies of predator avoidance, but to our knowledge very few papers have directly used GUDs in relation to pest management strategies. An opportunity for rodent control strategies lies in the integration of the LOF of rodents in EBRM methodologies. Rodent management could be more efficient and effective by concentrating on those areas where rodents perceive the least levels of predation risk. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND Rodenticide resistance to anticoagulants in Rattus norvegicus will lead to increased difficulties in combating these pest animals. Here, the authors present the results of a survey in the Netherlands where tissue samples and droppings were tested using a newly developed TaqMan PCR test for genotypic variation at codon 139 in the Vkorc1 gene associated with anticoagulant rodenticide resistance. Test results are linked to results of a questionnaire that was conducted among pest controllers. RESULTS Genetic mutations at codon 139 of the Vkorc1 gene in R. norvegicus can be encountered in many parts of the Netherlands. In 34/61 rat tails, a genotype was found that is linked to anticoagulant rodenticide resistance (56%). In droppings, 42/169 samples (25%) showed a resistance-mediating genotype. In addition, indications of a clear genetic substructure in the Netherlands were found. In some regions, only resistance-mediating genotypes were found, corroborating results from the questionnaire in which pest controllers indicated they suspected resistance to anticoagulant rodenticides. CONCLUSION This is the first study to demonstrate the presence of multiple genetic mutations at codon 139 of the Vkorc1 gene in R. norvegicus in the Netherlands. As rodenticides should keep their efficacy because they are a last resort in rodent management, more studies are urgently needed that link specific genetic mutations to the efficacy of active substances. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Genetically based resistance to anticoagulants has led to increasing difficulties in the control of rodents over recent decades. The possible impact of rodenticide-resistant rats on the infection risk of humans and livestock by zoonotic pathogens is generally unknown. Hence, in a monitoring programme in the German federal states of Lower Saxony and Hamburg, more than 500 Norway rats were analysed for both Tyr139Cys polymorphisms within the VKORC1 gene and zoonotic agents. RESULTS: Evidence of resistance was almost completely restricted to the known resistance area in southern Lower Saxony. Homozygous mutations were only found in urban areas sampled owing to the occurrence of rat control problems and were missing in bycatches of rats by muskrat trappers in rural areas. In more than 25% of the rats, zoonotic bacteria (Leptospira, Salmonella, Yersinia and Coxiella) were detected. There was no obvious correlation between the occurrence of rats carrying zoonotic pathogens and anticoagulant resistance. CONCLUSION: Zoonotic agents and genetically based resistance conferred by the Tyr139Cys polymorphism are both unevenly distributed in Lower Saxony. The study provides the basis for further studies focusing on districts with high levels of pathogens and resistance to assess the potential health risk of their combined occurrence. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Anticoagulants are the only available compounds in the EU to control rat populations. Resistance to anticoagulant rodenticides (antivitamin K or AVK) is described and widespread across Europe. The present objective was to determine whether resistance was associated with an increased potential for bioaccumulation of AVK in the liver. Rats were selected from three major resistant genetically identified strains across Europe: Y139C (Germany), Y139F (France) and L120Q (United Kingdom). The rats were housed in individual cages and fed chlorophacinone wheat bait (50 mg kg−1). Animals were assigned to groups for euthanasia either on day 1, 4, 9 or 14 (resistant rats) or on days 1 and 4 (susceptible rats). RESULTS: Chlorophacinone accumulated from day 1 to day 4 in all strains (maximum 160 µg liver−1) and remained stable thereafter. There was no significant difference between strains. Extensive metabolism of chlorophacinone was also found, and was similar (in nature and proportion of metabolites) across strains (3 OH-metabolites identified). Only the survival time differed significantly (L120Q > Y139C = Y139F > susceptible). CONCLUSIONS: Accumulation of chlorophacinone occurs from day 1 to day 4, and an equilibrium is reached, suggesting rapid elimination. Resistant and susceptible rats accumulate chlorophacinone to the same extent and only differ in terms of survival times. Resistant rats may then be a threat for non-target species for prolonged periods of time. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In the United States, new regulatory restrictions have been placed on the use of some second-generation anticoagulant rodenticides. This action may be offset by expanded use of first-generation compounds (e.g., diphacinone; DPN). Single-day acute oral exposure of adult Eastern screech-owls ( Megascops asio) to DPN evoked overt signs of intoxication, coagulopathy, histopathological lesions (e.g., hemorrhage, hepatocellular vacuolation), and/or lethality at doses as low as 130 mg/kg body weight, although there was no dose-response relation. However, this single-day exposure protocol does not mimic the multiple-day field exposures required to cause mortality in rodent pest species and non-target birds and mammals. In 7-day feeding trials, similar toxic effects were observed in owls fed diets containing 2.15, 9.55 or 22.6 ppm DPN, but at a small fraction (<5%) of the acute oral dose. In the dietary trial, the average lowest-observed-adverse-effect-level for prolonged clotting time was 1.68 mg DPN/kg owl/week (0.24 mg/kg owl/day; 0.049 mg/owl/day) and the lowest lethal dose was 5.75 mg DPN/kg owl/week (0.82 mg/kg owl/day). In this feeding trial, DPN concentration in liver ranged from 0.473 to 2.21 μg/g wet weight, and was directly related to the daily and cumulative dose consumed by each owl. A probabilistic risk assessment indicated that daily exposure to as little as 3-5 g of liver from DPN-poisoned rodents for 7 days could result in prolonged clotting time in the endangered Hawaiian short-eared owl ( Asio flammeus sandwichensis) and Hawaiian hawk ( Buteo solitarius), and daily exposure to greater quantities (9-13 g of liver) could result in low-level mortality. These findings can assist natural resource managers in weighing the costs and benefits of anticoagulant rodenticide use in pest control and eradication programs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nucleotide polymorphisms in the VKORC1 gene can be linked to anticoagulant rodenticide resistance in Norway rats ( Rattus norvegicus Berkenhout). This provides a fitness advantage to rats exposed to anticoagulant actives, but may also cause fitness costs. The vitamin K requirement and reproductive parameters of bromadiolone-resistant rats (Westphalian resistant strain; VKOR variant Tyr139Cys) and bromadiolone-susceptible Norway rats were compared. RESULTS: At vitamin K deficiency, blood clotting times increased in all homozygous resistant males within 8 days and in 80% of homozygous resistant females within 15 days. There was little effect on blood clotting in heterozygous males and no effect in heterozygous females and VKOR wild-type individuals. Litter size was about 20% higher in sensitive pairs compared with resistant pairs. Testes growth, male gonad weight, sperm motility and testis cell concentration were unaffected by the mutation. CONCLUSIONS: The VKOR variant Tyr139Cys causes considerable physiological cost in Norway rats in terms of vitamin K requirement and reproduction. This may affect the distribution and spread of resistant individuals in the wild. Decreased litter size of resistant parents seems to be due to lowered female reproductive performance, as there was no significant effect of the mutation on any aspects of male reproduction considered, but this requires further study. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Emerging resistance to anticoagulant rodenticides may significantly impair house mouse ( Mus musculus L.) control. As in humans and rats, sequence variants in the gene vitamin K epoxide reductase complex subunit 1 (VKORC1) of house mice are strongly implicated in the responses of mice to anticoagulants. This study gives a first overview of the distribution and frequency of such potentially resistance-conferring sequence variants in house mice, based on tissue samples from 30 populations in Germany, Switzerland and the Azores. RESULTS: Except for one population from south Germany, sequence variants were found in individuals from all locations sampled (29 out of 30 sites surveyed), with less than 10% of the individuals matching the wild-type genotype. The most frequent and widespread amino acid substitutions were Leu128Ser, Tyr139Cys and a group of linked sequence changes (Arg12Trp/Ala26Ser/Ala48Thr/Arg61Leu). Where these substitutions occurred as the sole variant, the proportion of homozygous individuals was 72-83%. CONCLUSIONS: An evaluation of published data revealed that the three most frequently found sequence variants are associated with a substantial loss of rodenticide efficacy of first-generation anticoagulants (e.g. warfarin, coumatetralyl), as well as the second-generation compound bromadiolone and most probably also difenacoum. Knowledge of the distribution and frequency of resistance-conferring sequence variants will stimulate their further functional characterisation and facilitate the choice of effective active substances for house mouse control. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: Rodents are mostly controlled by using anticoagulant rodenticides to minimise adverse effects along the food production chain. Genetic resistance to anticoagulant compounds occurs in populations of Norway rats (Rattus norvergicus) and other rodents throughout the world. This can be problematic for control operations and put predators and scavengers at risk because resistant prey individuals carry high anticoagulant loads. Single nucleotide polymorphisms (SNPs) in the vitamin K reductase complex subunit 1 (VKORC1) gene that are associated with rodenticide resistance are related to several pleiotropic effects including increased vitamin K requirement. The uptake of dietary vitamin K available from food sources present on farms including corn silage and garden herbs may mitigate such effects. We tested the preference for food rich in vitamin K1/3 in Norway rats susceptible or resistant to bromadiolone due to the homozygous amino acid variant Tyr139Cys. We also studied the effect of vitamin K consumption from several food sources on blood clotting in bromadiolone resistant and susceptible Norway rats. There was no general preference of rats for food sources rich in vitamin K. Surprisingly, there was no effect of vitamin K uptake on blood clotting times. However, the consumption of 4 of 5 corn silages prevented the rise in blood clotting times that otherwise occurred in vitamin K deficient bromadiolone resistant rats. This seemed to be due to substances with vitamin K activity present in silage and may contribute to the sustaining and spreading SNPs that are related to rodenticide resistance. As corn silage is becoming increasingly available to rats due to the expansion in generating bio-energy from corn silage, there may be a future increase in the occurrence of anticoagulant resistant Norway rats and associated problems in agro-ecosystems. [Copyright &y& Elsevier]

Summary: Polymorphisms in the vitamin K 2,3-epoxide reductase subcomponent 1 (vkorc1) of house mice (Mus musculus domesticus) can cause resistance to anticoagulant rodenticides such as warfarin []. Here we show that resistant house mice can also originate from selection on vkorc1 polymorphisms acquired from the Algerian mouse (M. spretus) through introgressive hybridization. We report on a polymorphic introgressed genomic region in European M. m. domesticus that stems from M. spretus, spans >10 Mb on chromosome 7, and includes the molecular target of anticoagulants vkorc1 []. We show that in the laboratory, the homozygous complete vkorc1 allele of M. spretus confers resistance when introgressed into M. m. domesticus. Consistent with selection on the introgressed allele after the introduction of rodenticides in the 1950s, we found signatures of selection in patterns of variation in M. m. domesticus. Furthermore, we detected adaptive protein evolution of vkorc1 in M. spretus (Ka/Ks = 1.54–1.93) resulting in radical amino acid substitutions that apparently cause anticoagulant tolerance in M. spretus as a pleiotropic effect. Thus, positive selection produced an adaptive, divergent, and pleiotropic vkorc1 allele in the donor species, M. spretus, which crossed a species barrier and produced an adaptive polymorphic trait in the recipient species, M. m. domesticus. [ABSTRACT FROM AUTHOR]

Abstract: A survey of the knowledge, attitudes and practices (KAP) of 100 rice farmers and 50 coconut farmers was conducted in the coastal lowland agro-ecosystems of the Sierra Madre Biodiversity Corridor, Luzon, Philippines to identify current rodent management practices and to understand the extent of rat damage and the attitudes of farmers to community actions for rodent management. Pests were most commonly listed as one of the three most important rice and coconut production constraints. Other major crop production constraints were typhoons and insufficient water. Farmers consider rats to be the major pest of coconut and of rice during the wet season rice crop, with average yield losses of 3.0% and 13.2%, respectively. Rice and coconut farmers practised a wide range of rodent management techniques. These included scrub clearance, hunting and trapping. Of the 42 rice farmers and 3 coconut farmers that applied rodenticides to control rodents, all used the acute rodenticide, zinc phosphide. However, only ten rice farmers (23.8%) applied rodenticides prior to the booting stage and only seven farmers (15.6%) conducted pre-baiting before applying zinc phosphide. The majority of farmers belonged to farmer organisations and believed that rat control can only be done by farmers working together. However, during the last cropping season, less than a third of rice farmers (31.2%) applied rodent management as a group. In order to reduce the impact of rodents on the farmers of the coastal lowlands of the Sierra Madre Biodiversity Corridor, integrated management strategies need to be developed that specifically target the pest rodents in a sustainable manner, and community actions for rodent management should be promoted. [ABSTRACT FROM AUTHOR]

A sample of 10 Norway rats (Rattus norvegicus) was taken for DNA resistance testing from an agricultural site in Kent where applications of the anticoagulant rodenticide bromadiolone had been unsuccessful. All animals tested were homozygous for the single nucleotide VKORC1 polymorphism tyrosine139phenylalanine, or Y139F. This is a common resistance mutation found extensively in France and Belgium but not previously in the UK. Y139F confers a significant level of resistance to first-generation anticoagulants, such as chlorophacinone, and to the second-generation compound bromadiolone. Another compound widely used in the UK, difenacoum, is also thought to be partially resisted by rats which carry Y139F. A silent VKORC1 mutation was also found in all rats tested. The presence of a third important VKORC1 mutation which confers resistance to anticoagulant rodenticides in widespread use in the UK, the others being Y139C and L120Q, further threatens the ability of pest control practitioners to deliver effective rodent control. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine the parasite fauna present in rodent coprolites collected from Cerro Casa de Piedra (CCP7), located in Perito Moreno National Park (P.N.P.M., 47°57′S and 72°05′W), Santa Cruz Province, Argentina. Eight coprolites obtained from the layer XIII of CCP7, with an antiquity considered as 7,920 ± 130 yr B.P., were examined for parasites. Each coprolite was whole processed, rehydrated, homogenized, spontaneously sedimented, and examined using light microscopy. Eggs of parasites were measured and photographed. All the samples were parasitized by nematodes, with 267 eggs of Trichuris sp., 24 eggs of an aspidoderid, and 3 capillariid eggs. The rodent host was tentatively identified as a species of Ctenomys, the hypogeic rodents endemic to South America. The finding of Paraspidodera in Patagonian samples represents new evidence that strengthens the co-phylogenies between nematodes of this genus and Ctenomys and reinforces the value of parasites as tags in paleoparasitology. [ABSTRACT FROM AUTHOR]

Abstract: Glutathione S-transferases (GSTs) catalyzing the conjugation of reduced glutathione (GSH) to a vast range of xenobiotics including insecticides were investigated in the psocid Liposcelis bostrychophila Badonnel. GSTs from susceptible and two resistant strains (DDVP-R for dichlorvos-resistant strain and PH3-R for phosphine-resistant strain) of L. bostrychophila were purified by glutathione–agarose affinity chromatography and characterized by their Michaelis–Menten kinetics towards artificial substrates, i.e., 1-chloro-2,4-dinitrobenzene (CDNB), in a photometric microplate assay. The specific activities of GSTs purified from two resistant strains were significantly higher than their susceptible counterpart. For the resistant strains, GSTs both showed a significantly higher affinity to the substrate GSH while a declined affinity to CDNB than those of susceptible strain. The inhibitory potential of ethacrynic acid was very effective with highest I 50 value (the concentration required to inhibit 50% of GSTs activity) of 1.21μM recorded in DDVP-R. Carbosulfan also exhibited excellent inhibitory effects on purified GSTs. The N-terminus of the purified enzyme was sequenced by Edman degradation, and the alignment of first 13 amino acids of the N-terminal sequence with other insect GSTs suggested the purified protein was similar to those of Sigma class GSTs. [Copyright &y& Elsevier]

The article presents a study on the resistance of Rattus norvegicus or commonly known as sewer rat to anticoagulant rodenticides in the urban environment. It aims to assess the effect of various management strategies for sewer rat control on the prevalence of resistance. Blood clotting response (BCR) tests, amplification refractory mutation system polymerase chain reaction (ARMS PCR) analysis, and additional sequencing of the VKORC1 gene were used to determine the prevalence of resistance of sewer rats samples from Copenhagen, Rødovre and Lyngby-Taarbæk in Denmark. Results of the study show a minimal level of anticoagulant resistance in the sewers irrespective of control strategy used while none of them had resistance-released mutations in the VKORC1 gene.

The newest measures for the control of harmful rodent populations are from the anticoagulant rodenticide group, which are divided into 2 subgroups: first and second generations, and indandione derivatives. Non-target organisms are potentially at risk of direct consumption of baits (primary hazard) and of eating poisoned rodents (secondary hazard). Anticoagulant rodenticides inhibit the enzyme vitamin K-dependent carboxylase and thus impair the reactivation of vitamin K1, indirectly affecting physiological blood coagulation. The diagnosis is made on the basis of clinical signs (massive hemorrhages), laboratory findings, and especially the changes in coagulation markers (APTT, PT, TT, PCT, ACT, FDPs, and PIVKA). The specific antidote is vitamin K1. The general prophylaxis consists of placing baits out of reach of animals, daily control of baits and dead rodents, which are to be timely removed. [ABSTRACT FROM AUTHOR]

Resistance to anticoagulant rodenticides in Rattus norvegicus is now estimated to cover an area of roughly 26 000 km2 in northwest Germany. The chemical compounds involved are warfarin, coumatetralyl, bromadiolone and, to a lesser extent, difenacoum. Recent investigations revealed that the resistance area is extending considerably further east than was previously recorded. The easternmost populations containing resistant individuals are now present in the city of Hannover, whereas it seems that on the southern edge the urbanised Ruhr Basin remains mostly unaffected by resistance problems. Reported control failures with house mice (Mus musculus/domesticus) suggest that resistance to high potency compounds may occur, but these await scientific confirmation. We propose that molecular genetic testing methodology should be exploited to improve monitoring of anticoagulant resistance and provide more accurate information to users of rodenticides. [ABSTRACT FROM AUTHOR]

The purpose of the study was to suppress a known natural focus of field fever exerting an influence on animal hosts of leptospires - small terrestrial mammals (s.t.m.) by rodenticide. After repeated application of the zinc phosphide rodenticide, the s.t.m. were regularly live-trapped and checked for leptospirosis by dark-field microscopy and culture of their renal tissue and serological examination. Isolated leptospira strains were typed by help of rabbit factor sera. The deratization influenced the s.t.m, structure considerably: the proportion of the dominant Microtus arvalis subjects - the main reservoirs of Leptospira kirschneri serovar Grippotyphosa - were gradually and substantionally reduced and, contrarily, the percentage of the potetial hosts subjects - Clethrionomys glareolus and Apodemus flavicollis - rose decisively over time. Changes in culture and serological positivity for leptospirosis of s.t.m, have also been enregistered. The highest original infestation of M. arvalis have slowly but strongly decreased while that of C. glareolus and A. flavicollis has increased decisively and reached its maximum within the last years of investigation. It is probable that these two animal species have undertaken the leading role in the maintenance of the natural focus of the field fever. In other animal species analogous trends were not registered. Based on these long-term findings, there exists the possibility to suppress only partially and temporarily the epizootic process of leptospirosis in a natural focus that can be desirable in some circumstances (building or free time activities, etc.). [ABSTRACT FROM AUTHOR]

The main objective of this study was to investigate the changes in free and protein-bound SH contents in methyl parathion-exposed rat tissues. The free and protein-bound SH levels are usually affected and depleted by oxidative stress-inducing agents. Results would indicate if methyl parathion toxicity partly results from depletion of sulfhydryl content of tissues. Six-week-old male Wistar albino rats were used in this study. Following exposure to methyl parathion for 3 months, the liver, the brain, and the kidney tissues were removed from the rats. The free and protein-bound SH contents were determined in these tissues. In addition, plasma lactate dehydrogenase levels were determined. Our results showed that methyl parathion exposure significantly lowers the free and protein-bound SH levels in rat tissues. However, lactate dehydrogenase activity in the blood plasma did not display any differences compared to the control group. The free SH concentrations in the control rat liver, brain, and kidney tissues were 3.78 ± 0.1 μmol/100 mg tissue, 1.56 ± 0.08 μmol/100 mg tissue, and 2.16 ± 0.08 μmol/100 mg tissue, respectively, whereas the free SH concentrations in rats exposed to methyl parathion were determined as 0.536 ± 0.1 μmol/100 mg tissue in the liver, 1.06 ± 0.1 μmol/100 mg tissue in the brain, and 0.108 ± 0.03 μmol/100 mg tissue in the kidney. The protein-bound SH concentrations in the liver and in the kidney in rats exposed to methyl parathion displayed a significant decrease also. However, the protein-bound SH level in the brain did not change significantly. These results indicate that methyl parathion exposure partially depletes the free and protein-bound SH levels. Thus, it was concluded that methyl parathion toxicity may partly result from oxidative stress. [ABSTRACT FROM AUTHOR]

Resistance to anticoagulant rodenticides in brown rats (Rattus norvegicus Berk.) is associated with pleiotropic effects, notably with an increased dietary vitamin K requirement. Owing to this disadvantage, resistance is believed to be selected against if anticoagulant selection is absent. In small experimental populations of wild brown rats, an investigation was carried out to establish whether tolerance to anticoagulant exposure changed over a period of 2 years. In the same populations, DNA microsateffite markers were used to infer parentage, and this made it possible to estimate reproductive success of sensitive and resistant rats and estimate effective population size, Ne. Even though there was evidence for a selection against resistant rats with high vitamin K requirement, anticoagulant tolerance was not seen to be significantly influenced in the absence of bromadiolone selection. As the population size under investigation was small, random genetic drift may have played a role in this. In the presence of bromadiolone selection, however, the tolerance was significantly increased, suggesting that continuous selection will increase the proportion of highly resistant rats in the population. It was found that, for both males and females, surprisingly few individuals contributed to the next generation with numerous offspring, and most breeders contributed with none or a single offspring. The expected higher reproductive success and consequent increase in proportional numbers of sensitive rats in the absence of anticoagulant selection could not be observed. Among the resistant rats, moderately resistant females were found to be better breeders than highly resistant breeders, but for resistant males the reverse was true. This could be explained by the fact that the increased vitamin K requirement results in sex differential selection; in highly resistant males the selection presumably takes place at the immature stage, whereas in females the vitamin K requirement becomes crucial at the reproductive stage, as vitamin K is not only essential for the blood clotting process but also for bone formation. [ABSTRACT FROM AUTHOR]

Since anticoagulant rodenticide resistance was first discovered in the United States in 1971, it has become apparent that the phenomenon is widespread. In cooperation with the Center for Disease Control, a nationwide surveillance program was initiated in 1977 to obtain statistically valid samples of rats from federally funded projects of the Urban Rat Control Program. A summary is given of the basic sampling, testing, and analysis components of this study. Problems encountered in all aspects of the first three years of the program are discussed along with results from the 40 completed samples. The 16 cities with significant Anticoagulant Resistance Problem Areas are distinguished from those in which resistance has merely been observed. Levels of resistance in various rat populations are discussed and recommendations are made in support of integrated pest management programs. Recent findings from retesting resistant rats, half of which die, are presented with regard to application of the surveillance program.

While the problem of anticoagulant resistance in commensal rodents has been well-documented from certain areas of northern Europe in recent years, this paper describes its first known occurrence in North America in 1971. Over a rural area of about 5 square miles in Johnson County, North Carolina, it was noted that attempts to control Norway rats using typical warfarin rodenticide bait were increasingly ineffective. Diphacinone was alternated with warfarin with no success. On one farm, 200 lbs of bait had been used in bait boxes in a single month. Laboratory trials on rats captured at this location demonstrated resistance. It was concluded that at this location, intensive use of anticoagulants (mostly warfarin) over a decade, in the absence of adequate sanitation and building maintenance, provided the selective agent to develop resistant populations. This likely will be repeated elsewhere in the U.S.

Anticoagulant rodenticides are widely used pesticides globally. They act by inhibiting vitamin K epoxide reductase in the liver, decreasing the synthesis of clotting factors II, VII, IX, and X. Sixty six cases of anticoagulant rodenticide toxicosis were found during a retrospective study conducted at the Veterinary Hospital and the Pathology Department of the Faculty of Veterinary Medicine Cluj-Napoca, in a period between January 2010 and June 2015. The inclusion criteria were: clinical signs of exposure, coagulation testing result and typical pathological findings characteristic for bleeding syndrome. History, clinical and pathological data were collected from the medical records of the dogs presented to our units. In the present study, 66 cases of anticoagulant toxicosis in dogs were described, the animals ranging in age from 2 months to 12 years. 31 dogs were male and 35 female. Two cases followed exposure to brodifacoum, 4 cases exposure to warfarin and in the other cases the type of anticoagulant was unknown. The most common clinical signs were dyspnea, lethargy, weakness, anemia/palor, melena, spontaneous subcutaneous and muscular hematoma, sublingual hematoma and ecchymoses. The most important lesions were represented by haemothorax, thymic hematoma in juvenile dogs, subcutaneous and muscular hematomas, hemoperitoneum, severe anemia, and ecchymotic hemorrhages in different tissues. In cases were coagulation testing was performed, prolonged partial thromboplastin time, prothrombin time and coagulation time were recorded. Anticoagulant rodenticide toxicosis is frequently found in our region, the most important diagnostic tools being coagulation testing and toxicological exam. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including the population of the grey squirrel or Sciurus carolinensis, genetic resistance of Norway rats or Rattus norvegicus to anticoagulant rodenticides and plant extracts as repellents.

The article discusses the development by rodents of a resistance to pesticides. Pesticides which have been used to kill rodent pests are derived from a compound called coumarin. Topics include an overview of research by Simone Rost and colleagues from the University of Würzburg in Germany, who have identified 18 resistance mutations in rodents from four continents and an explanation of how coumarin-derived compounds affect blood coagulation.

The article discusses the results of a special report on the complications arise in accidental ingestion of veterinary patients of bromethalin rodenticide conducted by Dr. Coppock. It mentions the propose intraosseos administration of lipid emulsion using a well-established protocol as therapeutic option for veterinary patients. It also suggests that animal healthcare providers who treat bromethalin-intoxicated veterinary patients with lipid emulsion should take into careful actions.