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BACKGROUND After reports of management problems in practice, a survey was conducted to determine the presence of bromadiolone-resistant animals in different house mouse ( Mus musculus L.) populations in Serbia. A 21 day no-choice feeding test was carried out to examine the resistance of house mice to bromadiolone. Eighty house mice collected from four locations (ten males and ten females per location) were tested for bromadiolone tolerance. Surviving animals and their F1 offspring were screened for mutations. The influence of VKOR variant, zygosity and sex on bromadiolone tolerance was analysed. RESULTS Bait intake and changes in body weight revealed different animal responses regarding susceptibility or resistance. Leu128Ser, Tyr139Cys and a new Ala21Thr polymorphism were detected in wild-born survivors and their F1 generation. However, not every individual with the polymorphisms Leu128Ser and Tyr139Cys survived the feeding test. VKOR variants and sex caused variations in bromadiolone tolerance. CONCLUSION For the first time it was shown that the VKOR variant, along with sex, is responsible for bromadiolone tolerance in house mice. Other factors influencing bromadiolone tolerance, including sex-specific factors, cannot be excluded. The tolerance levels of VKOR variants should be determined in further studies in order to evaluate the effectiveness of bromadiolone in sustainable management. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Many groups of closely related species have reticulate phylogenies. Recent genomic analyses are showing this in many insects and vertebrates, as well as in microbes and plants. In microbes, lateral gene transfer is the dominant process that spoils strictly tree-like phylogenies, but in multicellular eukaryotes hybridization and introgression among related species is probably more important. Because many species, including the ancestors of ancient major lineages, seem to evolve rapidly in adaptive radiations, some sexual compatibility may exist among them. Introgression and reticulation can thereby affect all parts of the tree of life, not just the recent species at the tips. Our understanding of adaptive evolution, speciation, phylogenetics, and comparative biology must adapt to these mostly recent findings. Introgression has important practical implications as well, not least for the management of genetically modified organisms in pest and disease control. [ABSTRACT FROM AUTHOR]

Recent studies of eukaryotes including human and Neandertal, mice, and butterflies have highlighted the major role that interspecific introgression has played in adaptive trait evolution. A common question arises in each case: what is the genomic architecture of the introgressed traits? One common approach that can be used to address this question is association mapping, which looks for genotypic markers that have significant statistical association with a trait. It is well understood that sample relatedness can be a confounding factor in association mapping studies if not properly accounted for. Introgression and other evolutionary processes (e.g., incomplete lineage sorting) typically introduce variation among local genealogies, which can also differ from global sample structure measured across all genomic loci. In contrast, state-of-the-art association mapping methods assume fixed sample relatedness across the genome, which can lead to spurious inference. We therefore propose a new association mapping method called Coal-Map, which uses coalescent-based models to capture local genealogical variation alongside global sample structure. Using simulated and empirical data reflecting a range of evolutionary scenarios, we compare the performance of Coal-Map against EIGENSTRAT, a leading association mapping method in terms of its popularity, power, and type I error control. Our empirical data makes use of hundreds of mouse genomes for which adaptive interspecific introgression has recently been described. We found that Coal-Map's performance is comparable or better than EIGENSTRAT in terms of statistical power and false positive rate. Coal-Map's performance advantage was greatest on model conditions that most closely resembled empirically observed scenarios of adaptive introgression. These conditions had: (1) causal SNPs contained in one or a few introgressed genomic loci and (2) varying rates of gene flow - from high rates to very low rates where incomplete lineage sorting dominated as a primary cause of local genealogical variation. [ABSTRACT FROM AUTHOR]

Blood clotting response (BCR) test is a faster method with fewer ethical constraints than feed-testing and is widely used to monitor resistance. The second-generation anticoagulant, bromadiolone is being used to control rodents all over India for the last several years. To investigate whether its use has resulted in development of resistance in house rat, Rattus rattus, BCR test was standardized. Plasma samples of 15 rats of both the sexes were pooled separately and diluted with phosphatebuffered saline (pH 7.4). Ten different dilutions of plasma i.e. 4, 5, 6, 8, 10, 20, 40, 60, 80, 100% were tested for Prothrombin Time (PT) and International Normalized Ratio (INR) using rabbit brain thromboplastin reagent in coagulation analyzer. Time to clotting was converted into percent clotting activity (PCA) relative to plasma dilutions, to plot a standard curve. The PT of 15.7 and 17.6 sec for 100% plasma corresponded to INR of 0.8 and 0.9 in male and female rats, respectively. PCA of 22.3% corresponded with PT and INR of 70.3 sec and 3.8, respectively in male rats and PCA of 27.6% corresponded with PT and INR of 63.6 sec and 3.5, respectively in female rats. Data for PT and INR and standard curve for PCA vs PT prepared during present study can be further used to determine current status of bromadiolone resistance in R. rattus populations based on discriminating dose of bromadiolone. [ABSTRACT FROM AUTHOR]

A recent analysis of the genomes of Darwin's finches revealed extensive interspecies allele sharing throughout the history of the radiation and identified a key locus responsible for morphological evolution in this group. The radiation of Darwin's finches on the Galápagos archipelago has long been regarded as an iconic study system for field ecology and evolutionary biology. Coupled with an extensive history of field work, these latest findings affirm the increasing acceptance of introgressive hybridization, or gene flow between species, as a significant contributor to adaptive evolution. Here, we review and discuss these findings in relation to both classical work on Darwin's finches and contemporary work showing similar evolutionary signatures in other biological systems. The continued unification of genomic data with field biology promises to further elucidate the molecular basis of adaptation in Darwin's finches and well beyond. [ABSTRACT FROM AUTHOR]

The wild North American sunflowers Helianthus annuus and H. debilis are participants in one of the earliest identified examples of adaptive trait introgression, and the exchange is hypothesized to have triggered a range expansion in H. annuus. However, the genetic basis of the adaptive exchange has not been examined. Here, we combine quantitative trait locus ( QTL) mapping with field measurements of fitness to identify candidate H. debilis QTL alleles likely to have introgressed into H. annuus to form the natural hybrid lineage H. a. texanus. Two 500-individual BC1 mapping populations were grown in central Texas, genotyped for 384 single nucleotide polymorphism ( SNP) markers and then phenotyped in the field for two fitness and 22 herbivore resistance, ecophysiological, phenological and architectural traits. We identified a total of 110 QTL, including at least one QTL for 22 of the 24 traits. Over 75% of traits exhibited at least one H. debilis QTL allele that would shift the trait in the direction of the wild hybrid H. a. texanus. We identified three chromosomal regions where H. debilis alleles increased both female and male components of fitness; these regions are expected to be strongly favoured in the wild. QTL for a number of other ecophysiological, phenological and architectural traits colocalized with these three regions and are candidates for the actual traits driving adaptive shifts. G × E interactions played a modest role, with 17% of the QTL showing potentially divergent phenotypic effects between the two field sites. The candidate adaptive chromosomal regions identified here serve as explicit hypotheses for how the genetic architecture of the hybrid lineage came into existence. [ABSTRACT FROM AUTHOR]

Central Eastern Asia, foremost the area bordering northern China and Mongolia, has been thought to be the geographic region where Norway rats (Rattus norvegicus) have originated. However recent fossil analyses pointed to their origin in southern China. Moreover, whereas analyses of fossils dated the species' origin as ∼ 1.2-1.6 million years ago (Mya), molecular analyses yielded ∼ 0.5-2.9 Mya. Here, to study the geographic origin of the Norway rat and its spread across the globe we analyzed new and all published mitochondrial DNA cytochrome-b (cyt-b; N = 156) and D-loop (N = 212) sequences representing wild rats from four continents and select inbred strains. Our results are consistent with an origin of the Norway rat in southern China ∼ 1.3 Mya, subsequent prehistoric differentiation and spread in China and Asia from an initially weakly structured ancestral population, followed by further spread and differentiation across the globe during historic times. The recent spreading occurred mostly from derived European populations rather than from archaic Asian populations. We trace laboratory strains to wild lineages from Europe and North America and these represent a subset of the diversity of the rat; leaving Asian lineages largely untapped as a resource for biomedical models. By studying rats from Europe we made the observation that mtDNA diversity cannot be interpreted without consideration of pest control and, possibly, the evolution of rodenticide resistance. However, demographic models explored by forward-time simulations cannot fully explain the low mtDNA diversity of European rats and lack of haplotype sharing with their source from Asia. Comprehensive nuclear marker analyses of a larger sample of Norway rats representing the world are needed to better resolve the evolutionary history of wild rats and of laboratory rats, as well as to better understand the evolution of anticoagulant resistance.

Field trials were conducted in Abbottabad - Balakot tract of the northern Pakistan for testing the effectiveness of groundnut - maize grain bait in delivering the lethal amount of strychnine alkaloid in controlling the Indian crested porcupine, Hystrix indica, during 2006-07. Indian crested porcupine is a severe forest and agricultural pest throughout southern Asia and the Middle East, including Pakistan. The results suggested that in case of pre-baiting trial, a 25% reduction in burrow activity was achieved in case of groundnut - maize (1:1) grain bait loaded with 2% strychnine alkaloid and supplemented with 5% saccharin and a 10% reduction could be achieved without saccharin supplementation. In case of without pre-baiting trial, a 10% reduction in burrow activity was recorded in case of saccharin supplemented groundnut - maize grain bait impregnated with strychnine alkaloid; while no reduction was recorded in case of no saccharin supplementation. The results of the study suggested that strychnine alkaloid is not an effective rodenticide for the control of Indian crested porcupine at least with the present bait and conditions. Further trials with low concentrations of strychnine alkaloid and decreasing the poison-baiting duration are suggested. [ABSTRACT FROM AUTHOR]

Background: In areas where the morphologically indistinguishable malaria mosquitoes Anopheles gambiae Giles and An. arabiensis Patton are sympatric, hybrids are detected occasionally via species-diagnostic molecular assays. An. gambiae and An. arabiensis exhibit both pre- and post-reproductive mating barriers, with swarms largely species-specific and male F1 (first-generation) hybrids sterile. Consequently advanced-stage hybrids (back-crosses to parental species), which would represent a route for potentially-adaptive introgression, are expected to be very rare in natural populations. Yet the use of one or two physically linked single-locus diagnostic assays renders them indistinguishable from F1 hybrids and levels of interspecific gene flow are unknown. Methods: We used data from over 350 polymorphic autosomal SNPs to investigate post F1 gene flow via patterns of genomic admixture between An. gambiae and An. arabiensis from eastern Uganda. Simulations were used to investigate the statistical power to detect hybrids with different levels of crossing and to identify the hybrid category significantly admixed genotypes could represent. Results: A range of admixture proportions were detected for 11 field-collected hybrids identified via single-locus species-diagnostic PCRs. Comparison of admixture data with simulations indicated that at least seven of these hybrids were advanced generation crosses, with backcrosses to each species identified. In addition, of 36 individuals typing as An. gambiae or An. arabiensis that exhibited outlying admixture proportions, ten were identified as significantly mixed backcrosses, and at least four of these were second or third generation crosses. Conclusions: Our results show that hybrids detected using standard diagnostics will often be hybrid generations beyond F1, and that in our study area around 5% (95% confidence intervals 3%-9%) of apparently ‘pure’ species samples may also be backcrosses. This is likely an underestimate because of rapidly-declining detection power beyond the first two backcross generations. Post-F1 gene flow occurs at a far from inconsequential rate between An. gambiae and An. arabiensis, and, especially for traits under strong selection, could readily lead to adaptive introgression of genetic variants relevant for vector control. [ABSTRACT FROM AUTHOR]

One outcome of interspecific hybridization and subsequent effects of evolutionary forces is introgression, which is the integration of genetic material from one species into the genome of an individual in another species. The evolution of several groups of eukaryotic species has involved hybridization, and cases of adaptation through introgression have been already established. In this work, we report on PhyloNet-HMM—a new comparative genomic framework for detecting introgression in genomes. PhyloNet-HMM combines phylogenetic networks with hidden Markov models (HMMs) to simultaneously capture the (potentially reticulate) evolutionary history of the genomes and dependencies within genomes. A novel aspect of our work is that it also accounts for incomplete lineage sorting and dependence across loci. Application of our model to variation data from chromosome 7 in the mouse (Mus musculus domesticus) genome detected a recently reported adaptive introgression event involving the rodent poison resistance gene Vkorc1, in addition to other newly detected introgressed genomic regions. Based on our analysis, it is estimated that about 9% of all sites within chromosome 7 are of introgressive origin (these cover about 13 Mbp of chromosome 7, and over 300 genes). Further, our model detected no introgression in a negative control data set. We also found that our model accurately detected introgression and other evolutionary processes from synthetic data sets simulated under the coalescent model with recombination, isolation, and migration. Our work provides a powerful framework for systematic analysis of introgression while simultaneously accounting for dependence across sites, point mutations, recombination, and ancestral polymorphism. [ABSTRACT FROM AUTHOR]

Copyright of Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The competence of a species for a zoonotic disease can be broadly defined as its ability to cause new infections, thereby increasing the fitness of the causative parasite (Merrill and Johnson 2020). Although scant evidence from amphibian disease systems suggests that evolved tolerance to pesticides could modify disease competence (Hua et al. 2017), less is known about zoonotic disease systems from mammals. Although chemical contaminants can alter disease competence (e.g., pesticides via suppressed immunity), there has been less focus on whether adaptive responses to contaminants can modify competence. [Extracted from the article]

Adaptive genetic variation has been thought to originate primarily from either new mutation or standing variation. Another potential source of adaptive variation is adaptive variants from other (donor) species that are introgressed into the (recipient) species, termed adaptive introgression. Here, the various attributes of these three potential sources of adaptive variation are compared. For example, the rate of adaptive change is generally thought to be faster from standing variation, slower from mutation and potentially intermediate from adaptive introgression. Additionally, the higher initial frequency of adaptive variation from standing variation and lower initial frequency from mutation might result in a higher probability of fixation of the adaptive variants for standing variation. Adaptive variation from introgression might have higher initial frequency than new adaptive mutations but lower than that from standing variation, again making the impact of adaptive introgression variation potentially intermediate. Adaptive introgressive variants might have multiple changes within a gene and affect multiple loci, an advantage also potentially found for adaptive standing variation but not for new adaptive mutants. The processes that might produce a common variant in two taxa, convergence, trans-species polymorphism from incomplete lineage sorting or from balancing selection and adaptive introgression, are also compared. Finally, potential examples of adaptive introgression in animals, including balancing selection for multiple alleles for major histocompatibility complex ( MHC), S and csd genes, pesticide resistance in mice, black colour in wolves and white colour in coyotes, Neanderthal or Denisovan ancestry in humans, mimicry genes in Heliconius butterflies, beak traits in Darwin's finches, yellow skin in chickens and non-native ancestry in an endangered native salamander, are examined. [ABSTRACT FROM AUTHOR]

Copyright of Pesticides & Phytomedicine / Pesticidi i Fitomedicina is the property of Institute of Pesticides & Environmental Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Field studies guided by genetic monitoring of Vkorc1 need to be done to implicate mutations conclusively with rodent control problems due to the presence of animals resistant to anticoagulant rodenticides. Rodent control success in relation to Vkorc1 genotypes in house mice ( Mus musculus domesticus) was studied on two farms (I and II) in Germany. Tests were carried out to determine whether certain resistance profiles and Vkorc1 genotypes displayed dynamics over the course of sequential treatments with warfarin and difenacoum that were consistent with single nucleotide polymorphisms (SNPs) in Vkorc1 as indicators of resistance. RESULTS: On farms I and II, respectively, three (A to C) and two (A and B) types of control problem with anticoagulants (i.e. proxies for resistance) were encountered in spatially segregated subunits: A = none; B = control problems with warfarin but not with difenacoum; C = control problems with both anticoagulants. Unexpectedly, resistance was encountered in a population where only Vkorc1 wild-type mice were detected. In addition, the Arg58Gly Vkorc1 variant was found not to correlate with observed control failures. CONCLUSION: Control problems were encountered that cannot be explained by Vkorc1 coding or intronic SNPs, and therefore are likely due to non-coding Vkorc1 SNPs or due to other genetic or non-genetic factors. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Anticoagulant resistance in Norway rats at foci in Belgium, Denmark, France, Germany, the Netherlands and the United Kingdom is genetically characterised by the same single nucleotide polymorphism (SNP) and consequent amino acid exchange from tyrosine to cysteine at location 139 of the vkorc1 gene (i.e. tyrosine139cysteine or Y139C). The purpose of this study was to assess the degree of resistance among rats at two infested farm sites in the Y139C focus in Westphalia, Germany, using blood clotting response (BCR) tests, and to determine the practical efficacy of applications of a commercial 50 ppm difenacoum bait (Neokil™) against them. RESULTS: BCR tests showed that the difenacoum resistance factor (RF) among the Y139C rats was about 2.5. DNA analysis for the Y139C mutation revealed that it was present among rats at the two sites with a prevalence of 75 and 93%. Applications of difenacoum bait at the two sites achieved 86.8 and 59.9% control. The different outcomes did not appear to be due to differences either in the degree and prevalence of resistance or in the quantities of poisoned bait consumed. CONCLUSION: The study showed that, although the RF for difenacoum among rats carrying the Y139C SNP was apparently low, an acceptable level of control of resistant Norway rat infestations was not achieved using difenacoum. Continued use of anticoagulants against rats that are resistant to them will exacerbate resistance problems in terms of both increased severity and prevalence. These conclusions are likely to apply elsewhere in Europe where the Y139C SNP occurs. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Species identification through noninvasive sampling is increasingly used in animal conservation genetics, given that it obviates the need to handle free-living individuals. Noninvasive sampling is particularly valuable for elusive and small species such as rodents. Although rodents are not usually assumed to be the most obvious target for conservation, of the 21 species or near-species present in Iberia, three are considered endangered and declining, while several others are poorly studied. Here, we develop a genetic tool for identifying all rodent species in Iberia by noninvasive genetic sampling. To achieve this purpose, we selected one mitochondrial gene [cytochrome b (cyt- b)] and one nuclear gene [interphotoreceptor retinoid-binding protein ( IRBP)], which we first sequenced using tissue samples. Both genes allow for the phylogenetic distinction of all species except the sibling species Microtus lusitanicus and Microtus duodecimcostatus. Overall, cyt- b showed higher resolution than IRBP, revealing a clear barcoding gap. To allow these markers to be applied to noninvasive samples, we selected a short highly diagnostic fragment from each gene, which we used to obtain sequences from faeces and bones from owl pellets. Amplification success for the cyt- b and IRBP fragment was 85% and 43% in faecal and 88% and 64% in owl-pellet DNA extractions, respectively. The method allows the unambiguous identification of the great majority of Iberian rodent species from noninvasive samples, with application in studies of distribution, spatial ecology and population dynamics, and for conservation. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

BACKGROUND: The aim of this study was to determine the incidence and the level of resistance to bromadiolone among rats on farms suspected of being foci of resistance by using the international normalised ratio (INR)-based blood clotting response (BCR) test. Whether the level of reduced susceptibility constitutes 'practical resistance' was subsequently determined in field trials. RESULTS: The 2.5 multiple of the ED50 baseline was used to test for the incidence of resistance, and higher multiples in the range of the suspected resistance factor were used to investigate the degree of resistance. The ED50 values of bromadiolone in resistant rats were confirmed in the range 4.70-7.05 mg kg−1 for males and 4.62-6.61 mg kg−1 for females. Variations within these ranges appeared between farms. According to the BCR resistance tests, 50-100% of rats were classified as resistant prior to the field trials; 29-100% of rats survived the treatments. CONCLUSION: BCR tests based on the use of the INR and baselines are suitable for determining the incidence and for assessing the level of resistance in populations of Norway rats. The majority of rats of the Westphalian resistant strain, characterised by the Y139C marker in VKOR, are resistant to bromadiolone under practical control conditions. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Anticoagulant resistance is known as one of the major factors interfering with rodent control. Within this context we investigated the distribution of anticoagulant resistance in Flanders, northern Belgium. From 2003 to 2005, we tested 691 rats from different locations with blood clotting response tests for their susceptibility to the anticoagulant compounds warfarin, bromadiolone and difenacoum. Of these, 119 were also screened for a mutation in the VKORC1 gene that is suspected to be responsible for anticoagulant resistance. Warfarin resistant rats were found in the western and eastern parts of Flanders. The same distribution pattern was found for bromadiolone with the exception of the south-eastern area, where this form of resistance was largely absent. We detected difenacoum resistance in only six rats and did not observe any resistant rats in the central part of Flanders. Susceptible rats were found all over Flanders. Genetic analyses showed that anticoagulant resistance in Belgium was related to two different mutations in VKORC1, namely Y139F and L120Q. Our results indicate that rodent control should be regionally tailored to be most effective. [ABSTRACT FROM AUTHOR]

The anti-vitamin Ks (AVKs) are widely used to control rodent populations. They inhibit Vitamin K regeneration by the Vitamin K Epoxide Reductase (VKOR) and cause a fatal hemorrhagic syndrome. Because of repeated use, some populations of commensal rodents have expressed resistance to these compounds. In Franche-Comté (France), the water vole exhibits cyclic population outbreaks. A second generation AVK, bromadiolone, has been used for the last 20 years to control vole populations. The aim of this study is to determine whether these repeated treatments could have led to the development of resistance to AVKs in water vole populations. We conducted enzymatic and genetic studies on water voles trapped in treated and non treated plot. The results indicate that voles from the most heavily treated area exhibit enzymatic changes in VKOR activity hence arguing for resistance to AVKs and that an intronic haplotype on the vkorc1 gene seems to be associated with these enzymatic changes. [ABSTRACT FROM AUTHOR]

We tested the efficacy and palatability of nine commercial rodenticide bait formulations on Polynesian rats ( Rattus exulans), roof rats ( R. rattus), and house mice ( Mus musculus). Efficacy varied by rodenticide tested and rodent species. Generally, rodenticides were more effective against mice than for either of the rat species, and mice tended to consume more rodenticide bait than the laboratory chow alternative food. Efficacy was generally highest for the second-generation anticoagulants tested; however, this varied across products and one-first-generation rodenticide had similar effectiveness. Bait acceptance (palatability) also varied both by rodenticide and by rodent species. Acceptance was the lowest for the acute rodenticides. Bait acceptance appeared to substantially affect the efficacy of rodenticides; materials that were not well accepted produced lower mortality rates. Rodenticide products currently registered for use in Hawaii performed less effectively in this study than other available products not yet registered. Although markets for rodent control products for use on islands are limited, there are advantages to having additional products registered for island use in agriculture, conservation, and public health. [ABSTRACT FROM AUTHOR]

The buff-breasted rat ( Rattus flavipectus) is a major agricultural pest across China. Warfarin-resistant animals have been found in several major provinces in China, and are hampering effective control. Molecular mechanisms underlying resistance to anticoagulant rodenticides have been determined for other species, but genetic information regarding resistance in R. flavipectus remains unknown. The vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) encoded by VKORC1 gene is the molecular target of coumarin anticoagulants, and amino acid substitutions in VKORC1 coding-regions have been reported as one of the supposed mechanisms of warfarin resistance. Here, lethal feeding test in R. flavipectus ( n = 36) was conducted in Zhanjiang, China. Four animals (11%) survived the test period of 25 days and were identified as warfarin resistance. Polymorphism across the whole genome DNA sequence of the VKORC1 gene was screened out and compared with resistant and non-resistant rats. A total of nine single nucleotide polymorphisms (SNPs) were identified including seven SNPs in introns and two SNPs in exons, and the SNP (2317A > G) located in exon 3 led to the amino acid substitution (Tyr139Cys) in VKORC1 protein. Based on the characteristics of Tyr139Cys mutation of VKORC1 in humans or rats and its relationship with warfarin-resistance, Tyr139Cys mutation may be one mutation responsible for anticoagulant resistance in R. flavipectus. Given the low numbers of resistant rats in our feeding test, wider surveillance, tests of resistance development in a larger wild population and further researches on the genetic mechanisms of anticoagulant resistance in R. flavipectus are necessary. [ABSTRACT FROM AUTHOR]

Pathogen–plant host coevolutionary interactions exert strong natural selection on both organisms, specifically on the genes coding for effectors (pathogens), as well as on those coding for effector targets and R proteins (plant hosts). Natural selection leaves behind DNA sequence signatures on such genes and on linked genomic regions. These signatures can readily be detected by studying the patterns of intraspecies polymorphisms and interspecies divergence of the DNA sequences. Recent developments in DNA sequencing technology have made whole-genome studies on patterns of DNA polymorphisms : divergence possible. This type of analysis, called ‘population genomics’, appears to be powerful enough to identify novel effector–effector target genes. Here, we provide an overview of the statistical tools used for population genomics and their applications. This is followed by a brief review of evolutionary studies on plant genes involved in host–pathogen interactions. Finally we provide an example from our study on Magnaporthe oryzae. [ABSTRACT FROM AUTHOR]

Registration is a necessarily sophisticated evaluation process applied to vertebrate pesticide products. Although conducted to minimise any potential impacts upon public health, the environment and food production, the all-encompassing process of registration can stifle innovation. Vertebrate pesticides are rarely used to control pest animals in food crops. In contrast to agrochemicals, relatively small amounts of vertebrate pesticides are used (<0.1%), usually in solid or paste baits, and generally by discrete application methods rather than by broad-scale spray applications. We present a hierarchy or sliding scale of typical data requirements relative to application techniques, to help clarify an evolving science-based approach which focuses on requiring data to address key scientific questions while allowing waivers where additional data have minor value. Such an approach will facilitate the development and delivery of increasingly humane, species-targeted, low residue pesticides in the New World, along with the phasing out of less desirable chemicals that continue to be used due to a lack of alternatives. [ABSTRACT FROM AUTHOR]

The article discusses a study on the distribution of Vitamin K epoxide reductace complex subunit1 (VKORC1) mutations in brown rats (Rattus norvegicus) in France to examine its resistance to anticoagulants. It says that the tail pieces of 200 rats were used for the study. It states that the blast software was used to detect homozygous mutations in the VKORC1 exons. The results revealed the association of Y139F mutation with the resistance of the rats to anticoagulants.

The article focuses on the possible utility of pest management principles (PMPs) and methodology for pest control decisions under the Animals Act of 1986 in Great Britain. It explains the flexibility of the ethical principles and applications used in the context of laboratory animals indicates that it can also be applied in pest management. It also cites that PSPs are dynamic concepts which mean that further changes can be created in order to adopt to the contingencies or to scientific progress.

The attractiveness and efficacy of four anonymous anticoagulant-free alternative rodenticides (active ingredients cellulose or plaster) were tested on wild strain groups of house mice ( Mus musculus Linnaeus) and brown rats ( Rattus norvegicus Berkenhout) in laboratory choice and no-choice experiments. In no-choice tests, the rodenticide product was offered ad libitum to the animals for 21 days (mice) and 10 days (rats), respectively. In choice tests, the rodenticide product and non-poisoned food were offered for 28 days (mice) and 14 days (rats). Two products with cellulose (C1 and C2) as the active ingredient were tested against both mice and rats. In two no-choice tests with mice, all animals died within 14 days (C1) and 21 days (C2); in a third no-choice test, 11% (2/18) of mice survived (C1: 21 days). In all three tests, numerous incidents of cannibalism were observed. The attractiveness of cellulose baits was tested for one product (C1) in three trials against normal food pellets. In all trials, bait consumption was low and all mice survived (15–34 days). Two no-choice trials with cellulose baits (C1) were conducted on groups of Rattus norvegicus; 11 of 12 rats survived the bait feeding period and no cannibalism or sign of aggression between conspecifics was observed. Two plaster-based (CaSO4·0.5H2O) products (P1 and P2) were tested against both mice and rats; in no-choice tests, only one mouse ( n= 20) and no rats ( n= 8) were killed, although the baits proved to be attractive for rats and mice in choice tests. The results of these experiments suggest that neither cellulose-based nor plaster-based rodenticides are suitable agents for the control of Mus musculus and Rattus norvegicus. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the susceptibility of bromadiolone in wild and laboratory Mus musculus L. or house mice in Buenos Aires, Argentina. It involves animals that were captured in poultry farms and a laboratory strain and were fed with bromadiolone. It concludes that there is a presence of anticoagulant resistant Mus musculus L. which may be influenced by the feeding behaviour of animals.

1. Norway rat Rattus norvegicus populations are usually controlled with toxic baits, but this approach is increasingly recognized as having negative welfare and environmental impacts. An integrated strategy that relies less on rodenticides is therefore required. Here we investigate the possibility of using a resource-based approach to rat population management. 2. Structurally complex habitats provide rat populations with nest sites and opportunities to avoid predators; modifying habitats to reduce structural complexity might reduce their potential to support rat populations. As part of an integrated approach, this could be more sustainable than relying exclusively on lethal control. However, in order to target habitat management efforts most effectively with minimum impact on other species, an understanding of habitat utilization by Norway rats is required. 3. In this study, rat populations on farms in the north-east of England were monitored by radio-tracking and population counts before and after a single phase of habitat modification. Rats living near farm buildings utilized areas with high levels of cover; habitat modification reduced the survival rate and size of these rat populations. Rats living in field margins also preferred areas with high levels of cover, but they had significantly bigger home ranges than rats living near farm buildings and were largely unaffected by small-scale habitat management. 4. Synthesis and applications. Our results indicate that habitat management near farm buildings has the potential to reduce the size of rat populations. As part of an integrated approach, this technique offers a way of reducing reliance on rodenticides. Habitat use by rats within the wider farm landscape suggests that land management practices have the potential to influence the size and distribution of rat populations; many game-rearing practices and environmental policies designed to create habitats for ‘desirable’ farm wildlife, inadvertently create desirable habitats for rats. [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]

This paper presents a reappraisal of the blood clotting response (BCR) tests for anticoagulant rodenticides, and proposes a standardised methodology for identifying and quantifying physiological resistance in populations of rodent species. The standardisation is based on the International Normalised Ratio, which is standardised against a WHO international reference preparation of thromboplastin, and allows comparison of data obtained using different thromboplastin reagents. The methodology is statistically sound, being based on the 50% response, and has been validated against the Norway rat (Rattus norvegicus) and the house mouse (Mus domesticus). Susceptibility baseline data are presented for warfarin, diphacinone, chlorophacinone and coumatetralyl against the Norway rat, and for bromadiolone, difenacoum, difethialone, flocoumafen and brodifacoum against the Norway rat and the house mouse. A 'test dose' of twice the ED50 can be used for initial identification of resistance, and will provide a similar level of information to previously published methods. Higher multiples of the ED50 can be used to assess the resistance factor, and to predict the likely impact on field control. [ABSTRACT FROM AUTHOR]

Warfarin-susceptible and warfarin-resistant Norway rat (Rattus norvegicus) strains from France were studied to determine the mechanism of resistance to warfarin. As recently suggested by other authors, mutations in the vitamin K epoxide reduction subunit 1 (VKORC1) gene are the basis anticoagulant resistance. We found one of the seven previously described mutations (Y139F) for VKORC1, and calculated the kinetic parameters of vitamin K epoxide reductase (VKOR) in resistant (homozygous for Y139F) and susceptible rats. In resistant rats, VKOR activity was lower and also less inhibited by warfarin (20 μM) than in susceptible rats. Difethialone (20 μM) inhibited VKOR activity in both strains. The maximum rate (Vmax) and affinity constant (Km) of the VKOR in resistant rats was lowered compared to those obtained in susceptible rats. Consequently, the enzymatic efficiency (Vm/Km) of the VKOR was similar between resistant and susceptible rats. VKOR activity in warfarin-resistant rats was poorly inhibited by warfarin. A low expression of mRNA encoding the VKORC1 gene was observed in resistant rats. These findings appear to support the hypothesis that several different mechanisms are involved in warfarin resistance in the strain of Rattus norvegicus we studied. [ABSTRACT FROM AUTHOR]

A new blood clotting response test was used to determine the susceptibility, to coumatetralyl and bromadiolone, of laboratory strains of Norway rat from Germany and the UK (Hampshire), and wild rats trapped on farms in Wales (UK) and Westphalia (Germany). Resistance factors were calculated in relation to the CD strain of Norway rat. An outbred strain of wild rats, raised from rats trapped in Germany, was found to be more susceptible to coumatetralyl by a factor of 0.5 - 0.6 compared to the CD strain. Homozygous and heterozygous animals of a strain of resistant rats from Westphalia were cross-resistant to coumatetralyl and bromadiolone, with a higher resistance factor for bromadiolone than that found in both UK strains. Our results show that the degree of altered susceptibility and resistance varies between strains of wild rat and between resistance foci. Some wild rat strains may be more susceptible than laboratory rat strains. Even in a well-established resistance area, it may be difficult to find infestations with resistance high enough to suspect control problems with bromadiolone, even after decades of use of this compound. [ABSTRACT FROM AUTHOR]

We investigated the relationship between the severity and incidence of resistance among Norway rats (Rattus norvegicus) on a farm in Wales and the subsequent outcome of a practical rodent control operation. Bromadiolone resistance factors were estimated for rats trapped on the farm using the blood clotting response test, and were found to be 2 to 3 for male rats and approximately 6 for females. The incidence of resistance in the rat population was high. Infestation size was estimated by census baiting and tracking, and was found to be substantial, with a maximum of 6.5 kg of bait being eaten on a single night. A proprietary rodenticide (Deadline™), containing 0.005% bromadiolone, was used to control the infestation. The duration of baiting was 35 days and, according to the two methods of assessment used, treatment success was in the region of 87 and 93%. No evidence was observed of a significant impact of resistance on the rat control operation, and the remaining rats of this very heavy infestation would probably have been controlled if baiting had continued for longer. [ABSTRACT FROM AUTHOR]

1. Monitoring of exposure to pesticides in many countries shows extensive exposure of predators to anticoagulant rodenticides, which are used to control rats. Many predators and scavengers are declining in numbers, and exposure to rodenticides might therefore be of importance in conservation biology.2. Predators and scavengers of poisoned rats are at most risk of secondary poisoning. However, several predatory species of conservation concern rarely eat rats, implicating non-target small mammals as the major route of exposure. For the first time, this research investigated the importance of non-target small mammals as routes of exposure to rodenticide for predators and scavengers in the UK.3. Exposure studies of non-target small mammals were carried out alongside routine rat control at five sites, around agricultural buildings (n = 2) and feed hoppers for game birds (n = 3).4. Three non-target rodent species fed on rodenticide from bait boxes during routine rat control treatments. A large proportion (48·6%) of individuals in local populations ate the bait: woodmiceApodemus sylvaticuswere most exposed, followed by bank volesClethrionomys glareolusthen field volesMicrotus agrestis.5. Local populations of non-target small mammals declined significantly following rodenticidal rat control but their relative proportions did not change significantly. Populations recovered partially after 3 months, depending on the time of the year relative to the breeding cycle.6. Synthesis and applications.Our results clearly demonstrate that routine rat control reduced local populations of non-target small mammals. This may limit the food supply of some specialist predators. Most importantly, this demonstrates a significant route of exposure of predators and scavengers of small mammals to secondary poisoning. Rodenticides are applied on farms and game estates across the UK. Hence the results of this study are indicative of non-target rodenticide exposure nationally. Mitigation requires a shift from the current reliance on rodenticides to ecologically based rodent management, involving improvements in site management and the adoption of good farming practice.Journal of Applied Ecology(2005)42, 118 –128doi: 10.1111/j.1365-2664.2005.00997.x [ABSTRACT FROM AUTHOR]

In populations that are distributed across steep environmental gradients, the potential for local adaptation is largely determined by the spatial scale of fitness variation relative to dispersal distance. Since altitudinal gradients are generally characterized by dramatic ecological transitions over relatively short linear distances, adaptive divergence across such gradients will typically require especially strong selection to counterbalance the homogenizing effect of gene flow. Here we report the results of a study that was designed to test for evidence of adaptive divergence across an altitudinal gradient in a natural population of deer mice, Peromyscus maniculatus. We conducted a multilocus survey of allozyme variation across a steep altitudinal gradient in the southern Rocky Mountains that spanned several distinct biomes, from prairie grassland to alpine tundra. As a control for the effects of altitude, we also surveyed the same loci in mice sampled along a latitudinal transect through the prairie grassland that ran perpendicular to the east-west transect. We used a coalescent-based simulation model to identify loci that deviated from neutral expectations, and we then assessed whether locus-specific patterns of variation were nonrandom with respect to altitude. Results indicated that the albumin locus (Alb) reflects a history of diversifying selection across the altitudinal gradient. This conclusion is supported by two main lines of evidence: (1) Alb was characterized by levels of divergence across the altitudinal transect that exceeded neutral expectations in two consecutive years of sampling (in contrast to the spatial pattern of variation across the latitudinal transect), and (2) levels of divergence at the Alb locus exhibited a positive association with altitudinal distance in both years (in contrast to the pattern observed at unlinked loci). We conclude that clinal variation at the Alb locus reflects a balance between gene flow and... [ABSTRACT FROM AUTHOR]

Presents a study that examined vitamin K requirement of Danish anti-coagulant-resistant Norway rats using a vitamin K deficient feeding test. Materials and methods; Results of the study; Conclusion.

Phil Russell, formerly of Aventis Crop Protection and former Chairman of FRAC, discusses what 'resistance' is, why it is a problem and what we can do to combat it. [ABSTRACT FROM AUTHOR]