Brown Rats Rattus Norvegicus Research Articles

Prevalence and risk factors of Leptospira infection in urban brown rats (Rattus norvegicus), Vienna, Austria

Leptospirosis is a worldwide bacterial zoonosis which incidence is expected to increase in conjunction with global change. In urban ecosystems, synanthropic rats are the key source of Leptospira infection in humans and other animals. Risk assessment and prediction of human leptospirosis require investigations of the environment associated with the bacteria and infection patterns in the reservoir hosts. The objective of this study was to address the prevalence of mixed Leptospira infection in the lungs and kidneys of brown rats captured in three sites of the city centre of Vienna, Austria, between 2016 and 2018. A total of 96 brown rats were examined for the presence of Leptospira using PCR. Occurrence of mixed Leptospira infections was explored through next-generation sequencing (NGS). A logistic regression model was built to predict the individual infection status using morphological and land-use data. Overall, the prevalence of Leptospira interrogans in the kidney was 25% but varied among sites (0–36%). We did not evidence any pulmonary nor mixed infections. Host body mass and sex were strong predictors of Leptospira carriage in the sampled rats (relative variable importance (RVI) = 0.98 and 0.89, respectively) while the presence of water affected it moderately (RVI = 0.44). Our findings demonstrate that NGS is an unbiased approach to the direct characterisation of mixed leptospiral infections that could provide further insights into the ecology of Leptospira. Future surveillance programmes should consider the use of rats as sentinels for the early detection of emerging pathogenic Leptospira in urban ecosystems.

Effects of the Black Rat (Rattus rattus) on Tropical Islands: Helpful or Harmful?

Rats do not enjoy a particularly good reputation, especially in regards to the environment. Many know rats to be pests, spreaders of diseases, and overall ruinous to the environments they are introduced to.The focus of this poster is on the impact of black rats (Rattus rattus) and brown rats (Rattus norvegicus) on tropical islands. Many studies support the idea that introduced rats destroy the ecosystems of tropical islands by negatively impacting the islands' bird populations. However, a study suggested that rats might have a positive impact on tropical islands through spreading seeds of different plants across the terrain. However, after the compilation and analysis of several studies regarding rats' impacts on tropical islands, it was concluded that the negative impact of rats on tropical islands outweigh the positive impacts.

Paw Morphology in the Domestic Guinea Pig (Cavia porcellus) and Brown Rat (Rattus norvegicus).

Mammals have adapted to different habitats, food types, and modes of locomotion, which are reflected in a diverse range of paw morphologies. While the behavior of rats and guinea pigs is well defined, especially in terms of their locomotor and foraging behaviors, the anatomy of their foot pads has not yet been explored and compared. This study investigated adaptations in paw morphology in the domestic guinea pig (Cavia porcellus) and the brown rat (Rattus norvegicus). We predicted that rat paws would display adaptations associated with paw dexterity for handling prey items and climbing, whereas guinea pig paws would support mechanical pressure absorption for a herbivorous, sedentary, and terrestrial lifestyle. Using histology techniques and scanning electron microscope, we show that rat paws have many small, deformable pads that are relatively spaced out to enable movement. The pads are clustered toward the anterior of the foot, which coincides with where the most force occurs during locomotion, as rats walk on their toes and toward the front of their paw. Guinea pigs had fewer and larger pads and the posterior pad of the forepaw was textured and contained cartilage, which may act to reduce friction and compression during standing and locomotion. We suggest that differences in paw morphology in rat and guinea pig are associated with loading during locomotion as well as paw mobility. Examining paw morphology and movement abilities in more species will give further insights in to the evolution of locomotor adaptations and paw dexterity in rodents. Anat Rec, 302:2300-2310, 2019. © 2019 American Association for Anatomy.

Discovery of two highly divergent negative-sense RNA viruses associated with the parasitic nematode, Capillaria hepatica, in wild Mus musculus from New York City.

Recent advances in high-throughput sequencing technology have led to a rapid expansion in the number of viral sequences associated with samples from vertebrates, invertebrates and environmental samples. Accurate host identification can be difficult in assays of complex samples that contain more than one potential host. Using unbiased metagenomic sequencing, we investigated wild house mice (Mus musculus) and brown rats (Rattus norvegicus) from New York City to determine the aetiology of liver disease. Light microscopy was used to characterize liver disease, and fluorescent microscopy with in situ hybridization was employed to identify viral cell tropism. Sequences representing two novel negative-sense RNA viruses were identified in homogenates of wild house mouse liver tissue: Amsterdam virus and Fulton virus. In situ hybridization localized viral RNA to Capillaria hepatica, a parasitic nematode that had infected the mouse liver. RNA from either virus was found within nematode adults and unembryonated eggs. Expanded PCR screening identified brown rats as a second rodent host for C. hepatica as well as both nematode-associated viruses. Our findings indicate that the current diversity of nematode-associated viruses may be underappreciated and that anatomical imaging offers an alternative to computational host assignment approaches.

Comparison of Candida Albicans Fatty Acid Amide Hydrolase Structure with Homologous Amidase Signature Family Enzymes

Fatty acid amide hydrolase (FAAH) is a well-characterized member of the amidase signature (AS) family of serine hydrolases. The membrane-bound FAAH protein is responsible for the catabolism of neuromodulatory fatty acid amides, including anandamide and oleamide, that regulate a wide range of mammalian behaviors, including pain perception, inflammation, sleep, and cognitive/emotional state. To date, limited crystal structures of FAAH and non-mammalian AS family proteins have been determined and used for structure-based inhibitor design. In order to provide broader structural information, the crystal structure of FAAH from the pathogenic fungus Candida albicans was determined at a resolution of 2.2 Å. A structural comparison with a brown rat Rattus norvegicus FAAH as well as with other bacterial AS family members, MAE2 and PAM, showed overall similarities but there were several discriminative regions found: the transmembrane domain and the hydrophobic cap of the brown rat FAAH were completely absent in the fungal FAAH structure. Along with these results, a phylogenetic analysis of 19 species within the AS family showed that fungal FAAHs diverged from a common ancestor before the separation of eukarya and prokarya. Taken together, this study provides insights into developing more potent inhibitors of FAAH as well as expanding our knowledge of the relationships between AS family members.

Ectoparasites of brown rats (Rattus norvegicus) in Grenada, West Indies

Background and Aim:Arthropod ectoparasites (mites, lice, ticks, and fleas) on common house rats or brown rats (Rattus norvegicus) are known to transmit zoonotic pathogens and diminish rat health. To the best of our knowledge, there is no published information regarding the prevalence of ectoparasites on R. norvegicus in Grenada. This study aimed to determine the prevalence and types of ectoparasites present on brown rats from Grenada.Materials and Methods:One hundred sixty-eight rats were collected live from the parishes of St. George and St. David, Grenada, from May to July 2017. Following euthanasia, external parasites were collected using fine combs, thumb forceps, and paper tape. Tape samples and free specimens were placed in containers with 70% ethanol. External parasites were evaluated using dissection microscopy.Results:Over 2000 ectoparasites were collected from 149 of the 168 trapped rats (88.7%). Ectoparasites identified included mesostigmatid mites (found on 84.6% of infested rats), fur mites in the families Atopomelidae and Listrophoridae (67.1%), Polyplax spp. lice (6.7%), fleas (3.4%), an unidentified larval tick (0.7%), and a mite in the family Myobiidae (0.7%). Infestation rates were higher in St. David Parish (86/89; 96.6%) than in St. George Parish (63/79; 79.7%) (p=0.001). When comparing sex and age, males had a marginal increase in infestation rate (83/89; 93.3%) compared to females (66/79; 83.5%) (p=0.054), and adults had an infestation rate of 90.7% (97/107) compared to juvenile rats who had a 66.7% (14/21) infestation rate.Conclusion:Brown rats in Grenada are heavily infested with ectoparasites, including known vectors of pathogens. Future studies will examine the prevalence of zoonotic pathogens in these arthropods.

The effect of fermented goat milk (kefir) fortified with vitamin D3 on total leukocyte levels in diabetic Rattus norvegicus rats

Purpose Hyperglycemia in type 2 diabetes mellitus increases inflammation through pancreatic beta-cell destruction. Goat milk (kefir) and vitamin D3 have antioxidant and anti-inflammatory properties that can reduce pancreatic beta cells. Increase in total leukocyte count is one of the inflammatory and complication markers of diabetes. This study aims to analyze the effect of fermented goat milk (kefir) fortified with vitamin D3 on total leukocyte counts in diabetic brown rat (Rattus norvegicus). Design/methodology/approach An experimental design with pre- and post-test methodology of control and experimental groups was used. A total of 24 male Wistar rats were divided into four groups: negative control (K−), positive control (K+), kefir treatment (P1) and kefir fortified with vitamin D3 treatment (P2). The control group consisted of healthy rats; the other groups consisted of rats which were given streptozotocin–nicotinamide injections. Before and after intervention, fasting blood glucose levels and total leukocytes counts were measured. Blood glucose levels were analyzed using the GOD–PAP method and leukocyte counts were analyzed using an automatic hematological analyzer. Findings There was a significant decrease in total leukocyte counts in the P2 group (from 26.5 ± 7.7 to 20.4 ± 10.4 [p < 0.05]). However, the decrease in leukocyte count in theP1 group was not significant (from 22.1 ± 9.3 to 16.5 ± 6.2). The decrease in blood glucose levels in theP2 group was −81.4 ± 203.0 but not significant. Originality/value Kefir with vitamin D3 fortification can significantly reduce total leukocyte counts in diabetes.

Genomic analyses reveal three independent introductions of the invasive brown rat (Rattus norvegicus) to the Faroe Islands.

Population genomics offers innovative approaches to test hypotheses related to the source and timing of introduction of invasive species. These approaches are particularly appropriate to study colonization of island ecosystems. The brown rat is a cold-hardy global invasive that has reached most of the world's island ecosystems, including even highly isolated archipelagoes such as the Faroe Islands in the North Atlantic Ocean. Historic records tell of rats rafting to the southern island of Suðuroy in 1768 following a shipwreck off the coast of Scotland, then expanding across the archipelago. We investigated the demographic history of brown rats in the Faroes using 50,174 SNPs. We inferred three independent introductions of rats, including to Suðuroy, the islands of Borðoy and Viðoy, and onto Streymoy from which they expanded to Eysturoy and Vágar. All Faroese populations showed signs of strong bottlenecks and declining effective population size. We inferred that these founder events removed low frequency alleles, the exact data needed to estimate recent demographic histories. Therefore, we were unable to accurately estimate the timing of each invasion. The difficulties with demographic inference may be applicable to other invasive species, particularly those with extreme and recent bottlenecks. We identified three invasions of brown rats to the Faroe Islands that resulted in highly differentiated populations that will be useful for future studies of life history variation and genomic adaptation.

Internal parasitic burdens in brown rats (Rattus norvegicus) from Grenada, West Indies

This study identified the endoparasites in Brown rat (Rattus norvegicus) during May to July 2017 in Grenada, West Indies. A total of 162 rats, 76 females and 86 males were trapped from St. George and St. David parishes in Grenada. The collected fecal samples were examined for parasitic eggs and/or oocysts using simple fecal flotation technique. Adult parasites found in the intestinal tract were examined for identification. The overall prevalence of intestinal parasites among rats was 79 %.Ten helminth species were recovered, several of which were reported for the first time in rodents in Grenada. The internal parasites consist of seven nematodes (Angiostrongylus spp., Nippostrongylus braziliensis, Heterakis spumosa, Strongyloides ratti, Aspiculuris tetraptera, Syphacia spp. and Protospirura spp.), one cestode (Hymenolepsis diminuta), one acanthocephalan (Moniliformis moniliformis) and one protozoa species (Eimeria spp.). The most prevalent zoonotic species were Angiostrongylus spp. (35.2%), Hymenolepsis diminuta (7.4%) and Moniliformis moniliformis (3.1%). Several nonzoonotic endoparasites; which included Nippostrongylus braziliensis (50.6%), Heterakis spumosa (15.4%), Strongyloides ratti (43.2%), Aspiculuris tetraptera (2.5%), Syphacia spp. (1.9%), Protospirura spp. (1.2%) and Eimeria spp. (4.7%) were also identified. The most prevalent parasites were Nippostrongylus brasiliensis (50.6%), Strongyloides ratti (43.2%) and Angiostrongylus spp. (35.2%). Co-infections occurred with up to six species per rat showing different combinations of parasitic infections.

Wild Rats, Laboratory Rats, Pet Rats: Global Seoul Hantavirus Disease Revisited.

Recent reports from Europe and the USA described Seoul orthohantavirus infection in pet rats and their breeders/owners, suggesting the potential emergence of a “new” public health problem. Wild and laboratory rat-induced Seoul infections have, however, been described since the early eighties, due to the omnipresence of the rodent reservoir, the brown rat Rattus norvegicus. Recent studies showed no fundamental differences between the pathogenicity and phylogeny of pet rat-induced Seoul orthohantaviruses and their formerly described wild or laboratory rat counterparts. The paucity of diagnosed Seoul virus-induced disease in the West is in striking contrast to the thousands of cases recorded since the 1980s in the Far East, particularly in China. This review of four continents (Asia, Europe, America, and Africa) puts this “emerging infection” into a historical perspective, concluding there is an urgent need for greater medical awareness of Seoul virus-induced human pathology in many parts of the world. Given the mostly milder and atypical clinical presentation, sometimes even with preserved normal kidney function, the importance of simple but repeated urine examination is stressed, since initial but transient proteinuria and microhematuria are rarely lacking.

Detection of Hepatitis B Virus-Like Nucleotide Sequences in Liver Samples from Murine Rodents and Asian House Shrews

In recent years, hepatitis B virus (HBV) has been detected in some species of animals. In this study, we found HBV-like nucleotide sequences in murine rodents and Asian house shrews (Suncus murinus) collected in China. A total of 801 animals were trapped. We found that 0.48% (3/624) of the murine rodents and 1.69% (3/177) of Asian house shrews were positive for HBV-like DNA. Detection of HBV-like DNA in brown rats (Rattus norvegicus), rice-field rat (Rattus losea), and Asian house shrews indicated that these species of animals might be hosts for HBV. However, none of the HBV-like DNA-positive animals was additionally positive for anti-HBV antibodies or hepatitis B surface antigen. A 585 bp nucleic acid sequence, mapping to a hepadnavirus, was extracted from rice-field rat, and bores strong resemblance to human HBV genotype B sequences. Further research is required to investigate the hepadnaviruses within the murine rodent and Asian house shrew populations to uncover the origin and zoonotic potential of HBV.

Morphological and molecular description of Sarcocystis ratti n. sp. from the black rat (Rattus rattus) in Latvia.

Rodents have been widely studied as intermediate hosts of Sarcocystis; however, only a few reports on these parasites in the black rat (Rattus rattus) are known. Having examined 13 black rats captured in Latvia, sarcocysts were found in skeletal muscles of two mammals and were described as Sarcocystis ratti n. sp. Under a light microscope, sarcocysts were ribbon-shaped, 0.9-1.3 × 0.09-0.14mm in size and had a thin (0.8-1.3μm) and smooth cyst wall. The lancet-shaped bradyzoites were 8.3 × 4.3 (7.5-9.3 × 3.9-4.8) μm. Under a transmission electron microscope, the cyst wall was up to 1.3μm thick, wavy, the ground substance appeared smooth, type 1a-like. Morphologically, sarcocysts of S. ratti were somewhat similar to those of S. cymruensis, S. rodentifelis, and S. dispersa-like previously identified in the brown rat (Rattus norvegicus). On the basis of 18S rDNA, 28S rDNA, and cox1, significant genetic differences (at least 2.3, 4.5, and 5.8%, respectively) were observed when comparing S. ratti with other Sarcocystis species using rodents as intermediate hosts. While ITS1 sequences of S. ratti were highly distinct from other Sarcocystis species available in GenBank. Phylogenetic and ecological data suggest that predatory mammals living near households are definitive hosts of S. ratti.

Alien war: ectoparasite load, diet and temporal niche partitioning in a multi-species assembly of small rodents

Interspecific interactions shape the structure of animal communities, and they rely on a number of multifactorial mechanisms, including e.g. activity rhythms, ectoparasite prevalence, predation pressure and food habits. Despite this, no study has analysed multispecies interactions by combining such a high number of aspects, mostly because the experimental manipulation of studied populations is rarely possible. In our work, we assessed several aspects of interspecific interactions in a rodent assembly composed by three species, by examining diet and temporal- niche partitioning, as well as relevant ectoparasite load and predation pressure, in a natural environment. We analysed stomach contents and ectoparasite load of 78 individuals belonging to all the species, whereas activity rhythms were measured with camera trapping (2200 night-traps, throughout 1 year). Our findings showed that the largest-sized species, i.e. the brown rat Rattus norvegicus was the strongest competitor and may affect diet, temporal behaviour and susceptibility to parasites of smaller-sized ones, i.e. the black rat Rattus rattus and the house mouse Mus domesticus. Larger-sized species showed a broader trophic niche with respect to smaller-sized ones, whereas the smallest species seemed to avoid the largest ones by shifting its temporal activity when the latter was mostly inactive. Larger-sized species may also act as potential predators towards smaller ones, which are also more vulnerable to ectoparasite infestation and to the predation by the only raptor bird present in the study area, the barn owl Tyto alba. We therefore highlight the importance to carry out community-wide studies, to understand interspecific intraguild relationships.

Psorergatidae mite infestation in the brown rat Rattusnorvegicus (Rodentia, Muridae): the first record of Psorergatesrattus (Acariformes, Prostigmata) in Europe

Psorergates rattus Fain & Goff, 1986 has been found in the brown rat Rattus norvegicus (Berkenhout, 1769) in Poland.The species has previously been found only once, in the tail base of the brown rat in the United States. In the present case, ten rats from two localities in Poland (Pomerania) were examined and infestation was discovered in 20% of them, with a total of 12 mites found. This is not only the first discovery of the species in Poland and the second globally, but also the first observation of representatives of Psorergatidae in rodents of the genus Rattus in Europe. Moreover, immature specimens of P. rattus have been observed for the first time.The infestation was asymptomatic, although in the earlier study mange was observed despite the relatively low density of the mites, which indicates a potential pathogenic threat not only to wild rat populations, but also to laboratory animals and pets.

Detection of serum antibodies against Leptospira spp. in brown rats (Rattus norvegicus) from Grenada, West Indies.

Background and Aim:Leptospirosis is an emerging disease of animals and humans. Among rodents brown rats (Rattus norvegicus) are an important reservoir of bacteria Leptospira. There is a paucity of information on reservoirs of Leptospira in Grenada. This study was conducted to estimate the prevalence of antibodies against Leptospira spp. in brown rats in a densely human populated area of Grenada.Materials and Methods:Blood samples from 169 brown rats were collected and sera screened for antibodies against Leptospira spp. using enzyme-linked immunosorbent assay.Results:Among a total of 169 brown rats trapped in two parishes in Grenada, 77/169 (45.5%) were positive for Leptospira spp. antibodies. A significant difference in seropositive population of brown rats between two collection sites was observed. No differences were found between sex and age of seropositive rats.Conclusion:Due to the close contact of brown rats with humans in Grenada, rats should be considered a high-risk factor in transmission of Leptospira to humans. Appropriate preventive measures should be instituted to prevent the transmission of Leptospira infection to humans.

First detection of Hepatitis E virus (Orthohepevirus C) in wild brown rats (Rattus norvegicus) from Great Britain.

In the United Kingdom, there has been an increase in the number of hepatitis E virus (HEV) infections in people annually since 2010. Most of these are thought to be indigenously acquired Orthohepevirus A genotype 3 (HEV G3), which has been linked to pork production and consumption. However, the dominant subgroup circulating in British pigs differs from that which is found in people; therefore, an alternative, potentially zoonotic, source is suspected as a possible cause of these infections. Rodents, brown rats (Rattus norvegicus) in particular, have been shown to carry HEV, both the swine HEV G3 genotype and Orthohepevirus C, genotype C1 (rat HEV). To investigate the prevalence of HEV in British rodents, liver tissue was taken from 307 rodents collected from pig farms (n = 12) and other locations (n = 10). The RNA from these samples was extracted and tested using a pan‐HEV nested RT‐PCR. Limited histopathology was also performed. In this study, 8/61 (13%, 95% CI, 5–21) of brown rat livers were positive for HEV RNA. Sequencing of amplicons demonstrated all infections to be rat HEV with 87%–92% nucleotide identity to other rat HEV sequences circulating within Europe and China (224 nt ORF‐1). Lesions and necrosis were observed histologically in 2/3 samples examined. No rat HEV RNA was detected in any other species, and no HEV G3 RNA was detected in any rodent in this study. This is the first reported detection of rat HEV in Great Britain. A human case of rat HEV infection has recently been reported in Asia, suggesting that rat HEV could pose a risk to public health.

Cryptosporidium spp. in wild rats (Rattus spp.) from the Hainan Province, China: Molecular detection, species/genotype identification and implications for public health.

Wild rats (Rattus spp.) carry many zoonotic pathogens including Cryptosporidium. Due to the close proximity of rats to humans in urban environments, the potential for disease transmission is high. Cryptosporidium is a protozoan parasite which when ingested causes serious human illness. Despite its importance, genetic characterization of Cryptosporidium in wild rats in the Hainan province of China has not been performed. In this study, we analyzed the occurrence and genetics of Cryptosporidium in wild rats from Hainan, China. From December 2017 to October 2018, 150 wild rats were captured and fresh fecal material was collected from intestinal sections. Rat species were identified by PCR-based amplification and analysis of the vertebrate cytochrome b (cytb) gene. Cryptosporidium was examined by PCR amplification of the partial small subunit of ribosomal DNA (SSU rDNA). C. viatorum were subtyped by PCR analysis of the gp60 gene. A total of four rat species were identified including Asian house rats (Rattus tanezumi) (n = 46), brown rats (Rattus norvegicus) (n = 56), Edward's long-tailed rats (Leopoldamys edwardsi) (n = 38) and muridae (Niviventer fulvescens) (n = 10), with Cryptosporidium positive rates of 73.9%, 28.6%, 55.3% and 40.0%, respectively (average infection rate: 50.0%, 75/150. Sequence analysis confirmed the presence of four Cryptosporidium species and two genotypes including C. viatorum (n = 11); C. occultus (n = 2); C. muris (n = 1); and C. erinacei (n = 1); rat genotypes III (n = 13) and IV (n = 47). Three novel subtypes of C. viatorum were identified in 6 of the 11 infected Edward's long-tailed rats: XVcA2G1a (n = 4), XVcA2G1b (n = 1) and XVdA3 (n = 1). The identification of human pathogenic C. viatorum and zoonotic C. occultus, C. muris and C. erinacei, suggested that wild rats infected with Cryptosporidium pose a threat to human health. Taken together, these findings highlight the need to control the rat population in Hainan, China. The need to improve the public awareness of the risk of disease transmission from wild rats to humans is also highlighted.

Brown rat demography reveals pre-commensal structure in eastern Asia before expansion into Southeast Asia.

Fossil evidence indicates that the globally distributed brown rat (Rattus norvegicus) originated in northern China and Mongolia. Historical records report the human-mediated invasion of rats into Europe in the 1500s, followed by global spread because of European imperialist activity during the 1600s–1800s. We analyzed 14 genomes representing seven previously identified evolutionary clusters, and tested alternative demographic models to infer patterns of range expansion, divergence times, and changes in effective population (Ne) size for this globally important pest species. We observed three range expansions from the ancestral population that produced the Pacific (diverged ∼16.1 kya), eastern China (∼17.5 kya), and Southeast (SE) Asia (∼0.86 kya) lineages. Our model shows a rapid range expansion from SE Asia into the Middle East and then continued expansion into central Europe 788 yr ago (1227 AD). We observed declining Ne within all brown rat lineages from 150–1 kya, reflecting population contractions during glacial cycles. Ne increased since 1 kya in Asian and European, but not in Pacific, evolutionary clusters. Our results support the hypothesis that northern Asia was the ancestral range for brown rats. We suggest that southward human migration across China between the 800s–1550s AD resulted in the introduction of rats to SE Asia, from which they rapidly expanded via existing maritime trade routes. Finally, we discovered that North America was colonized separately on both the Atlantic and Pacific seaboards, by evolutionary clusters of vastly different ages and genomic diversity levels. Our results should stimulate discussions among historians and zooarcheologists regarding the relationship between humans and rats.

Anticoagulant Resistance in Synanthropic Rodents in the Stara Zagora Region, Bulgaria

Abstract The anticoagulant rodenticides are the most commonly used toxicants to control rodents nowadays. Therefore, developing resistance to them is an issue of great importance for pest control. The aim of this study was to investigate the sensitivity of synanthropic rodents in the Stara Zagora region, Bulgaria to some of the most significant first (warfarin and coumatetralyl) and second (bromadiolone and brodifacoum) generation anticoagulants. Resistance tests were carried out by a standard protocol using lethal feeding period tests and blood clotting response tests according to the European and Mediterranean Plant Protection Organization (Paris, France) standard. Studies were performed on 278 wild synanthropic rodents – 67 house mice (Mus musculus), 153 roof rats (Rattus rattus) and 58 brown rats (Rattus norvegicus). The rodents belonged to 11 populations inhabiting 9 animal farms in the region of Stara Zagora, Southern Bulgaria. High-level resistance to warfarinwas established in 100% of surveyed house mice and 92.1% of roof rats. Resistance to coumatetralyl was registered in 62.5% of the tested roof rats. Low-level resistance to bromadiolone was found in 38.5% of the surveyed roof rats and 23.1% of house mice. There was no resistance registered in brown rats. The sensitivity of all three rodent species to the strategic anticoagulant brodifacoum was high, and there were no signs of resistance. The results proved the resistance among synanthropic rodents and led to the conclusion that the resistance in house mice and roof rats to warfarin and coumatetralyl tends to be the main issue in pest control.

Pesticides in agriculture

Pesticides in agriculture