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Context: Invasive rodents pose a substantial threat to biodiversity and are a leading cause of species decline and extinction on islands. Population suppression using ground-based methods is common practice, though arboreal behaviour of rodents may render control programs less effective. Aims: We aimed to quantify species-specific invasive rodent activity (Rattus rattus , R. exulans , Mus musculus) across three forest strata to determine the prevalence of arboreal rodent behaviour in a system that has undergone extensive long-term rodent baiting, and therefore assess the suitability of solely ground-based baiting in this system. Methods: We calculated rodent presence at the ground, mid-storey, and canopy using three detection methods (camera traps, chew cards and tracking tunnels) deployed for 30-day periods across three structurally distinct forest types (canopy heights ranged from 3.5 to 16.7 m). We developed continuous rodent activity indices for each method, which we paired with density estimates. Strata-specific species composition was determined using camera trap images. Key results: Rodent presence was recorded equally across all strata, with R. rattus dominating above-ground strata. Rodent densities differed significantly between forest types, which was largely consistent with activity indices. Conclusions: Our findings offer an additional explanation for reduced efficacy of long-term ground-based control programs: arboreal behaviour may exacerbate the reduction in efficacy often associated with long-term control. Implications: Effective management of invasive rodent species on islands is a global conservation challenge. Our findings suggest above-ground control may be required in some long-term suppression programs or eradication campaigns, particularly in the presence of the black rat. Introduced rodents are highly destructive island invaders the world over. Control programs are usually ground-based, however our study found that black rats (Rattus rattus) dominated the forest mid-storey and canopy, casting doubt on the effectiveness of solely ground-based programs. Including above-ground control in the conservationist's rodent control arsenal may improve outcomes for island biodiversity. [ABSTRACT FROM AUTHOR]

Aotearoa—New Zealand has only four rodent species, all introduced. In order of arrival, they are Pacific rat Rattus exulans, brown rat R. norvegicus, house mouse Mus musculus, and black rat R. rattus. Rodent management in New Zealand aims mainly to conserve indigenous biodiversity rather than to protect crops or manage diseases, as is usual elsewhere. We describe four major "regimes" and one major vision for rodent control in New Zealand to meet ecological restoration objectives. Current challenges for island eradications are for large islands that are remote or populated by people. Aerial 1080 is the only large‐scale (tens of thousands of hectares) option for black rat control, but its application requires adjustment to counter subsequent rapid black rat repopulation. Unfenced "ecosanctuaries" (mean 720 ha) use ground‐based traps and poisons to target mainly black rats and face constant reinvasion. Ecosanctuaries with mammal‐resistant fences (up to 3500 ha) limit reinvasion and target more pest species and have enabled the return of previously extirpated taxa to the main islands. Predator Free 2050 aims to eradicate the rat species (but not mice) plus some other introduced mammals from New Zealand by 2050. This vision is not attainable with current tools, but research and experimental management is exploring techniques and technologies. The large scale (to 100 000 ha) at which black rats are now targeted for control to extremely low abundance seems to be unique to New Zealand. [ABSTRACT FROM AUTHOR]

Norbormide is a uniquely selective rat toxicant for Rattus species, with rats being 100- to 150-fold more sensitive to norbormide toxicity than most other mammals and birds. Previously we reported that on completion of a 10-year program of targeted fundamental and applied synthetic chemistry and toxicology, taste aversion associated with this compound had been overcome. In 2020-2022, trials have been successfully completed on poultry farms with Norway rats and larger scale field trials were undertaken targeting ship rats using 1% norbormide paste baits. Firstly, the efficacy of norbormide-containing paste baits targeting rat infestations on poultry farms was proven with a 100% reduction of Norway rat populations on three different farms. Secondly, 100% reduction in ship rat abundance was achieved at two large field test sites; and no reduction was achieved at the untreated control site. These larger field trials are described in depth in this publication. Plans are progressing to complete product development and registration.

Simple Summary: Invasive species negatively affect native populations through predation, competition, and the potential introduction of health threats, such as parasites. Black rats (Rattus rattus) are among the worst invaders of islands, and a significant source of parasites infecting humans and other animals. This study conducted a screening for zoonotic and veterinary-relevant microparasites in wild rats from small islands in central Italy, including the Pontine Islands and Pianosa, where the primary hosts of the selected parasites were either absent or scarce. The aim was to investigate the potential role of rats as their host. Rats were kill-trapped and molecular analyses were performed on different tissues to identify microparasite presence. Results confirm that invasive species such as rats may contribute to an elevated parasitological threat to local wildlife and human communities in specific ecosystems. Notably, we documented the first record of Babesia divergens, typically associated with cattle and wild ungulates, in wild rats. Additionally, we confirmed the presence of Leishmania infantum on an island without dogs, which have traditionally been considered the primary hosts. Our study helps to document parasite distribution and interactions between parasites and introduced invasive hosts, and represents useful knowledge to inform public health and wildlife management policy. Invasive species have a detrimental impact on native populations, particularly in island ecosystems, and they pose a potential zoonotic and wildlife threat. Black rats (Rattus rattus) are invasive species that disrupt native flora and fauna on islands and serve as potential competent reservoirs for various pathogens and parasites. Microparasites screening was conducted in rat populations from small islands in central Italy (the Pontine Islands and Pianosa) with the aim of assessing the role of rats in maintaining infections, particularly in cases where key reservoir hosts were scarce or absent. We focused on microparasites of zoonotic and veterinary relevance. A total of 53 rats was kill-trapped and target tissues were analysed with molecular techniques. We observed the absence or very low prevalence of Anaplasma spp., while Babesia was found in rats from all locations, marking the first recorded instance of Babesia divergens in wild rats. Data from Pianosa strongly suggest the presence of an autochthonous Leishmania infantum cycle in the Tuscan archipelago islands. Neospora caninum was absent from all islands, even in areas where dogs, the main reservoirs, were present. Toxoplasma gondii was only recorded on the Pontine Islands, where genotyping is needed to shed light on infection dynamics. This study confirms that invasive species, such as rats, may be responsible for maintaining an increased parasitological threat to fauna and human communities in certain ecosystems. [ABSTRACT FROM AUTHOR]

A non-toxic liquid fertility control bait for rats has recently become commercially available (ContraPest® from SenesTech, Inc.). This product contains two chemicals, both of which impair spermatogenesis in male and reduce ovulations in female rats. We tested the efficacy of this bait in wild-caught adult black rats from the island of Hawai’i in a short-term laboratory trial. A control group (n = 25) was offered placebo bait and the treatment group (n = 25) was offered fertility control bait, both ad libitum, during a 15-day introduction period and during the first of four breeding rounds, for a total of 58 days of exposure. After treatment, all rats were provided placebo bait for the remainder of the study and randomly paired with mates from within their treatment groups for two additional breeding cycles. Treatment and control groups comprised 10 breeding pairs each, with random re-pairings between breeding rounds. The treatment group produced no litters during the first and second breeding rounds, while 70% of the control females produced litters. In the third breeding round, 70 days after stopping treatment, the treatment group produced three litters (six pups) compared to seven litters (24 pups) in the control group. During a fourth and final breeding round, control rats were crossed with treated rats, producing six litters (27 pups) from treated dams and nine litters (40 pups) from control dams, indicating no apparent infertility effect 99 days after cessation of treatment. This study demonstrates that the reproduction rate of wild-caught black rats can be chemically suppressed if provided ad libitum access to the fertility control bait under laboratory conditions.

Invasive ship rats (Rattus rattus) are the major threat to the native species and ecosystem of Goat Island (9.3 ha), New Zealand. The island is only 100 m away from the mainland, which imposes a risk of incursions by rats swimming over. Accessibility depends on weather and tide times which makes regular trap servicing complicated. In 2016 we extended an existing trapping grid of 8 kill traps (DOC200; Department of Conservation, New Zealand) with 10 self-resetting traps (Goodnature A24s; Goodnature Limited, Wellington, New Zealand) to improve current management and ideally achieve eradication. Before our study started, DOC200s on the island had not been serviced for six months. Rats were active even during the day and rat numbers were assumed to be high. The DOC200 kill traps were lured with an egg and A24s were lured with Goodnature automatic lure pumps (ALP) baited with chocolate formula for rats. The A24s were equipped with Goodnature digital strike counters to document the number of rats killed by the self-resetting traps. All devices were on average checked every 49 days from August 2016 to October 2017. DOC200s were reset after triggering or after three months, whichever occurred first. ALPs were replaced in January and July 2017. Gas cartridges of the A24s were replaced when the strike counter showed 20 or more. A substantial number of rats were killed on the island (242 by A24s and 27 by DOC200s) in 8,838 uncorrected trap nights between August 2016 to October 2017 (Table 1). The initial number of individuals killed by A24s in the first month after deployment in August 2016 was high. The number of rats removed by A24s remained at a high level from November 2016 until June 2017. The number of A24 kills varied widely between the beginnings of the breeding seasons across the two years, with 46 individuals killed between September and November 2016 but only 4 kills between August and October 2017. Even though initial trapping success was high, eradication could not be achieved and the self-resetting traps did not perform better than traditional kill traps once rat abundance was low. The Goodnature A24 has shown the potential to work effectively for initial knock-down when rat numbers and activity were high. The advantage over traditional single kill traps, like the DOC200, was the low need for servicing. However, once the population density was reduced to a lower level, this advantage vanished. Most kills by A24s happened during the breeding season in 2016 in the first third of the study. In the last three months of the project the kill numbers did not differ meaningfully from the DOC200 kill numbers. Even though trapping numbers were low, rat abundance was still assumed to be high. After our study had finished rat control on the island using these devices was continued by local community volunteers. A further 357 rats were caught between June 2018 and March 2020, indicating no decline in rat captures. On 1 September 2019 and 1 March 2020 tracking tunnel indices were 100% (K. Tricklebank pers. commun.). In March 2020 initial cost for a DOC200 was NZD$145.00. The purchase costs for a Goodnature A24 with lure and gas for 6 months was NZD$169.00 (excluding digital strike counter). For the first six months the differences in costs were moderate. However, after six months, the material costs for servicing a DOC200 was NZD$0.55 (one freerange egg), or less when using peanut butter. The servicing cost for a Goodnature A24 is NZD$19.00 (gas cartridge + ALP). On Goat Island, servicing costs for a six months period were approximately NZD$9.00 for eight DOC200s and NZD$190.00 for ten A24s. Higher costs for A24 purchase and servicing compared to DOC200 were not compensated by noteworthy higher kill numbers once rat numbers were reduced. However, A24s performed well during peak times and labour costs were not considered in our study. Self-resetting devices at one per hectare did moderately reduce rat numbers in an area where kill trap maintenance was time and cost intensive but suppressing to very low rat numbers or achieving eradication requires additional investment in the system (e.g., a combination of different tools including toxins or a higher density of devices).

On Aotea/Great Barrier Island, New Zealand, two invasive rat species (Pacific rats and ship rats) pose risks to the ecosystems and challenge the management in two sanctuaries. At Glenfern Sanctuary (83 ha) an eradication has successfully removed ship rats and a predator-proof fence prevents reinvasion. However, Pacific rats persist in low abundance. At Windy Hill Sanctuary (770 ha) intensive rodent control maintains both species at low abundance despite ongoing reinvasion. A capture-mark-recapture study was conducted between February and April in 2016 and repeated between July and September 2017 to determine population densities, confirm species composition, and analyse the effects of time, population density, and interspecific competition on rat behaviour. Live traps were monitored with camera traps to analyse behaviour of rats around traps. Population density and detection probability of Pacific rats varied between times reflecting seasonality in food abundance and rat reproduction. The detection probability of Pacific rats also differed between sites, being higher at Glenfern Sanctuary than at Windy Hill Sanctuary, presumably due to interspecific competition with ship rats. Where Pacific rats were the sole species they were captured in traps in the first night. However, in coexistence with ship rats, Pacific rat detection was delayed by at least ten days. Population density influenced the number of trap encounters and interactions but did not significantly influence the capture rate. Interspecific competition was identified as problematic for monitoring, controlling, and eradicating Pacific rats.

Mutations in Exon 1, 2 and 3 of the vitamin K epoxide reductase complex subunit 1 (Vkorc1) gene are known to lead to anticoagulant rodenticide resistance. In order to investigate their putative resistance in rodenticides, we studied the genetic profile of the Vkorc1 gene in Turkish black rats (Rattus rattus) and brown rats (Rattus norvegiens). In this context, previously recorded Ala21Thr mutation (R. rattus) in Exon 1 region, Ile90Leu mutation (R. rattus, R. norvegicus) in Exon 2 region and Leu120Gln mutation (R. norvegicus) in Exon 3 region were identified as "missense mutations" causing amino acid changes. Ala21Thr mutation was first detected in one specimen of Turkish black rat despite the uncertainty of its relevance to resistance. Ile90Leu mutation accepted as neutral variant was detected in most of black rat specimens. Leu120Gln mutation related to anticoagulant rodenticide resistance was found in only one brown rat specimen. Furthermore, Ser74Asn, Gln77Pro (black rat) and Ser79Pro (brown rat) mutations that cause amino acid changes in the Exon 2 region but unclear whether they cause resistance were identified. In addition, "silent mutations" which do not cause amino acid changes were also defined; these mutations were Arg12Arg mutation in Exon 1 region, His68His, Ser81Ser, Ile82Ile and Leu94Leu mutations in Exon 2 region and Ile107Ile, Thr137Thr, Ala143Ala and Gln152Gln mutations in Exon 3 region. These silent mutations were found in both species except for Ser81Ser which was determined in only brown rats. [ABSTRACT FROM AUTHOR]

The black rat (Rattus rattus) has become in a commensal relationship with humans and has been responsible for obvious damage to agriculture annually. In this study, clodinafop-propargyl bait (0.98%) was introduced to the adult male rats for seven days under laboratory conditions using a non-choice feeding method. The impact of the compound on the body and some organs' weights and functions was studied. Histopathological changes of the liver, kidney, and testis as well as sperm count, sperm morphology, vitality and motility percent were recorded. The efficiency of clodinafop-propargyl bait (0.98%) was evaluated under field conditions of crop stores. The results demonstrated that the body weight and testis of rats significantly decreased obviously after treatment. As well as, the treatment caused immoderate loss of water through the skin, losing appetite and slow movement of rats. While weights of the liver and kidney of treated rats significantly increased. In addition, the appearance of morphological and histopathological alterations in the liver, kidneys, and testis were observed. Also, significant elevation in serum (ALT and AST) enzymes, urea, creatinine and uric acid levels compared with control after treatment were recorded. Furthermore, sperm count, motility and vitality percentages significantly decreased (p≤0.05) in treated rats compared with controls. There were perspicuous abnormalities in the form of the head, neck, and tail of the spermatozoa in the treated rats. Regarding, sperm motility; non-progressive and immotile grades were significantly increased in treated rats compared with controls. Moreover, clodinafop-propargyl bait (0.98%) proved efficient under crop store conditions as it caused an 86.78 % reduction in the rat population. In conclusion, clodinafop-propargyl bait has a strong toxic impact on the liver, kidneys and reproductive system of male black rats affecting their fertility by destroying testicular integrity and function. Furthermore, the field results proved these impacts and achieved good results. We can conclude that this compound can be used in the control of black rats and can be used in rodent control programs. [ABSTRACT FROM AUTHOR]

Mutations in Exon 1, 2 and 3 of the vitamin K epoxide reductase complex subunit 1 (Vkorc1) gene are known to lead to anticoagulant rodenticide resistance. In order to investigate their putative resistance in rodenticides, we studied the genetic profile of the Vkorc1 gene in Turkish black rats (Rattus rattus) and brown rats (Rattus norvegicus). In this context, previously recorded Ala21Thr mutation (R. rattus) in Exon 1 region, Ile90Leu mutation (R. rattus, R. norvegicus) in Exon 2 region and Leu120Gln mutation (R. norvegicus) in Exon 3 region were identified as “missense mutations” causing amino acid changes. Ala21Thr mutation was first detected in one specimen of Turkish black rat despite the uncertainty of its relevance to resistance. Ile90Leu mutation accepted as neutral variant was detected in most of black rat specimens. Leu120Gln mutation related to anticoagulant rodenticide resistance was found in only one brown rat specimen. Furthermore, Ser74Asn, Gln77Pro (black rat) and Ser79Pro (brown rat) mutations that cause amino acid changes in the Exon 2 region but unclear whether they cause resistance were identified. In addition, “silent mutations” which do not cause amino acid changes were also defined; these mutations were Arg12Arg mutation in Exon 1 region, His68His, Ser81Ser, Ile82Ile and Leu94Leu mutations in Exon 2 region and Ile107Ile, Thr137Thr, Ala143Ala and Gln152Gln mutations in Exon 3 region. These silent mutations were found in both species except for Ser81Ser which was determined in only brown rats.

Most oceanic islands in the world have been invaded by rats, which have negative effects on the local biota. A number of studies have reported rat predation on amphibians, but there is scarce information on the relations of trophic interactions present in these cases (competition, origin of energy production sources, trophic levels). Using diet data and stable isotopes, we explored the trophic interactions of the Isla Mocha in southern Chile, in particular between Rattus rattus (Black rat, invasive) and Eupsophus insularis (Mocha Island ground frog, endemic). The results show an important overlap in the prey used by both species, in the trophic positions they occupy, in their isotope niches and the presence of isotopic signals attributable to the anurans in tissue samples of rats. Understanding the trophic relations between invaders and native species is an important challenge for the implementation of conservation plans. [ABSTRACT FROM AUTHOR]

Invasive species have a detrimental impact on native populations, particularly in island ecosystems, and they pose a potential zoonotic and wildlife threat. Black rats (Rattus rattus) are invasive species that disrupt native flora and fauna on islands and serve as potential competent reservoirs for various pathogens and parasites. Microparasites screening was conducted in rat populations from small islands in central Italy (the Pontine Islands and Pianosa) with the aim of assessing the role of rats in maintaining infections, particularly in cases where key reservoir hosts were scarce or absent. We focused on microparasites of zoonotic and veterinary relevance. A total of 53 rats was kill-trapped and target tissues were analysed with molecular techniques. We observed the absence or very low prevalence of Anaplasma spp., while Babesia was found in rats from all locations, marking the first recorded instance of Babesia divergens in wild rats. Data from Pianosa strongly suggest the presence of an autochthonous Leishmania infantum cycle in the Tuscan archipelago islands. Neospora caninum was absent from all islands, even in areas where dogs, the main reservoirs, were present. Toxoplasma gondii was only recorded on the Pontine Islands, where genotyping is needed to shed light on infection dynamics. This study confirms that invasive species, such as rats, may be responsible for maintaining an increased parasitological threat to fauna and human communities in certain ecosystems.

Black rats are among the world’s most invasive rodent species and are responsible for considerable agricultural losses and risks to human health through zoonotic disease. In Puerto Rico, rats may also compete with the primary rabies reservoir (the small Indian mongoose) for baits during oral rabies vaccination (ORV) programs. We evaluated black rat population density and home range size on the Cabo Rojo National Wildlife Refuge, southwestern Puerto Rico. We fitted 10 rats with VHF transmitters and tracked them using radio telemetry for approximately 4 weeks. We entered locations into ArcGIS and obtained minimum convex polygon (MCP) home range estimates. We established two plots of 55 snap traps and performed removal for 5 consecutive days during January and July, to correspond roughly with wet and dry seasons for this region. To calculate abundance, we entered snap trap data using a removal model approach in Program MARK. We calculated the effective trapping area by creating a buffer around the trapping area based on the square root of mean home range estimate. We divided the abundance calculated in MARK by the effective trapping area to calculate the estimated population density. Mean MCP home range estimate was 0.28 ha (SE: 0.05, range: 0.07-0.50 ha). Population density estimates were 114.7 (SE: 201.80) and 19.3 (SE: 6.85) per ha for January and July, respectively. To reduce the potential for rat consumption of ORV baits, wildlife managers should consider conducting ORV activities in Puerto Rico during periods of lower rat abundance or density.

Objective. the objective of the present work was the detection of Leishmania sp. in Rattus rattus tail base skin through polymerase chain reaction (PCR) techniques. Material and method. We analyzed 45 Rattus rattus skin samples from the urban area of the city of Corrientes in Argentina. The Leishmania spp detection was performed by nested PCR technique. Results. Leishmania DNA was detected in 22 samples out of 45 processed (49%) in the first round of amplification, and in 14 samples (31%) in the second round (31%). Conclusions. These results contribute to increase the existing information in our region on the possible relationship between Leishmania and Rattus rattus, considering the high prevalence found in skin added to the total absence of lesions. Other aspects should be further studied to establish the role of these animals in the epidemiological chain of the disease in an urban area endemic to leishmaniasis in other animal species. [ABSTRACT FROM AUTHOR]

Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that can cause severe disease in ruminants and humans. Epidemics occur mainly after heavy rainfall, which leads to a significant increase in the occurrence of RVFV-transmitting mosquitoes. During inter-epidemic periods, the virus is assumed to be maintained between mosquitoes, susceptible livestock and yet unknown wildlife. The widespread rodent Rattus rattus (black rat) has been suspected to be involved in RVFV maintenance. In order to elucidate its susceptibility and thus its possible role in the transmission cycle of the virus, an experimental infection study was performed. Black rats were subcutaneously infected with highly virulent RVFV strain 35/74 and euthanized on days 3, 14 and 28 post-infection. Additional black rats served as non-infected contact animals. The infected black rats showed high susceptibility to RVFV infection. Generation of RVFV-neutralizing antibodies was found, and the rats developed viraemias lasting up to 17 days. Viral RNA was found in tissues until the last day of the experiment. However, neither a clinical manifestation nor virus-induced histopathological lesions were observed in any rat. These findings indicate the persistence of RVFV in black rats without affecting the animals. In contact animals, no evidence of horizontal RVFV transmission was found, although the co-housed infected rats showed oral, rectal and conjunctival RVFV shedding. Results of this study point to an involvement of black rats in the RVFV transmission cycle, and further studies are needed to investigate their potential role in the maintenance of the virus. [ABSTRACT FROM AUTHOR]

Black rats are considered a carrier of arthropods that are vectors of diseases to animals and humans. No studies have ever been reported on ectoparasites of this rodent in Algeria. Where Rattus rattus was introduced recently in the south-eastern oasis and has taken refuge in palm groves. To identify the ectoparasites, richness, and prevalence of this species, we have collected 6237 arthropods from four species of lice, five mites, one tick, and flea's larvae, were collected from 462 infested rats of 484 (95.5%) total collected rats. The results showed that lice especially Polyplax spinulosa (n = 2888) and P. serrata (n = 1456) were the most trapped ectoparasites followed by Ornithonyssus bacoti (n = 1415). Otherwise, Atricholaelaps sp. (n = 10) was the least population. In addition, adult males of black rat were depicted as the most attacked category compared to females and other classes because of their mobility. Statistics confirm this ascertainment for sex (P = 0.0007) and age groups (P < 0.000). Hence, R. rattus is a favourable host target to parasites when transmission conditions allow it. All inventoried species were significantly greater (P < 0.0000) in summer than winter and decreased rainfall. [ABSTRACT FROM AUTHOR]

A large assemblage of small mammal and other small vertebrate bones was excavated within a relatively small area of a single room in a Roman villa close to the River Thames in South Oxfordshire. It is argued that these bones are the remains of barn owl pellets and that their presence shows that the roof on this room at least had remained intact for some time after either the entire building or this particular part of it had been abandoned as human habitation. The remains of several juvenile black rats were contained within the assemblage, making this the first record of black rats from a rural Romano-British setting in Oxfordshire and adding to the extremely small corpus of records of this species from a non-urban location anywhere in the country. Radiocarbon dates place the presence of rats and the abandonment of the villa during the second half of the fourth century. [ABSTRACT FROM AUTHOR]

The Nusa Tenggara island chain consists of an archipelago that runs roughly east-west in eastern Indonesia. As part of Wallacea, it has never been connected to any continental landmass, and has been subject to a variety of biological invasions that have populated the islands. Here, we examine the craniometric and molecular genetic records of several species of Rattus sensu lato in the island chain. We use the predictions of expanding population edge phenotypic selection in an effort to understand the movement of Rattus rattus and Rattus exulans through the archipelago. We also examine the mitochondrial haplotype networks of R. argentiventer, R. exulans, and the R. rattus Complex (RrC) and microsatellite allele frequency clustering patterns for the RrC, to examine relationships within and between Nusa Tenggara populations, and those of Asia and the Pacific where relevant for each taxon. In the RrC LIV and RrC LII haplotype networks, 20 haplotypes with seven from Nusa Tenggara were observed for RrC LIV, and 100 haplotypes with seven from Nusa Tenggara observed for RrC LII. The top performing RrC craniometric model had a negative association between size and distance from the easternmost point of the samples from Nusa Tenggara, consistent with increasing size moving west to east. The cytochrome b network for the R. exulans sequences comprised 14 haplotypes, with three observed from mainland Southeast Asia, one shared with Nusa Tenggara and regions further east, and another haplotype observed in Nusa Tenggara and in the Pacific. The R. exulans craniometric model selection produced four equally well performing models, with no migration scenario preferred. Finally, the haplotype network of R. argentiventer comprised 10 haplotypes, with six observed in Nusa Tenggara, including a relatively early cluster from the east of the archipelago. Our results are compatible with a polyphasic and polydirectional invasion of Nusa Tenggara by Rattus, likely beginning with RrC from the west to the east, an expansion of R. exulans from Flores, seemingly in no preferred overall direction, and finally the invasion of R. argentiventer from the east to the west. We find some support for the Dong Son drum maritime exchange network contributing to the distribution of the latter species.

Black rats are considered a carrier of arthropods that are vectors of diseases to animals and humans. No studies have ever been reported on ectoparasites of this rodent in Algeria. Where Rattus rattus was introduced recently in the south-eastern oasis and has taken refuge in palm groves. To identify the ectoparasites, richness, and prevalence of this species, we have collected 6237 arthropods from four species of lice, five mites, one tick, and flea’s larvae, were collected from 462 infested rats of 484 (95.5%) total collected rats. The results showed that lice especially Polyplax spinulosa (n = 2888) and P. serrata (n = 1456) were the most trapped ectoparasites followed by Ornithonyssus bacoti (n = 1415). Otherwise, Atricholaelaps sp. (n = 10) was the least population. In addition, adult males of black rat were depicted as the most attacked category compared to females and other classes because of their mobility. Statistics confirm this ascertainment for sex (P = 0.0007) and age groups (P < 0.000). Hence, R. rattus is a favourable host target to parasites when transmission conditions allow it. All inventoried species were significantly greater (P < 0.0000) in summer than winter and decreased rainfall.

Pterodroma leucoptera caledonica is a subspecies of Gould's Petrel endemic to New Caledonia. Its distribution, abundance and breeding biology are poorly known. Extensive surveys of New Caledonia between 1994 and 2014 located only two breeding colonies, and a further likely, but still unconfirmed; the total estimated size of the population could be of the order of 5000–7000 breeding pairs. Nesting burrows were situated either near streams or on slopes near ridges. The breeding phenology of caledonica was similar to that of the Australian leucoptera, but with a breeding calendar that lagged that of leucoptera by 2–4 weeks depending on year and breeding parameter. Breeding success was low, with evidence of a high level of predation of eggs, chicks and adults by rats, pigs and cats. Pigs also destroyed nesting burrows. Permanent bait stations installed to control rats at one colony appeared successful, but the control of pigs and cats is much more problematic. If, as expected, the level of predation observed at one colony extends across all breeding colonies, population decline is inevitable and extinction likely in the long term. With no populations of P. l. caledonica on predator-free offshore islands, translocation to such sites may be evaluated to safeguard this subspecies. In the meantime, we recommend that the global status of Gould's Petrel Pterodroma leucoptera be upgraded from Vulnerable to Endangered. [ABSTRACT FROM AUTHOR]

Gomortega keule is an endangered tree species, the single extant species of a monotypic family. It is safeguarded only in one protected area. Its recruitment and germination are low, possibly in part because rodents prey on the seeds. However, it remains unknown if any rodent preys upon its large fruit and if so, to what extent. In this work we aimed to evaluate the interaction and possible predation of the invasive species Rattus rattus on G. keule. We recorded with camera traps the visits and behaviour of different animal species with the fruit of G. keule. We obtained a total of 90 records. The only animal species that interacted with the fruit during the 14-day observation period was R. rattus, eating and carrying away the fruit. This could constitute an additional threat to G. keule. Despite the evidence of seeds chewed by rodents, it would be useful to document the fates of seeds to confirm our conclusions and understand this interaction. However, in the meantime we recommend increasing propagation and protection of seedlings, and also taking actions against R. rattus in the only protected area where this endangered tree is present. [ABSTRACT FROM AUTHOR]

Managing ecosystems in the face of complex species interactions, and the associated uncertainty, presents a considerable ecological challenge. Altering those interactions via actions such as invasive species management or conservation translocations can result in unintended consequences, supporting the need to be able to make more informed decisions in the face of this uncertainty. We demonstrate the utility of ecosystem models to reduce uncertainty and inform future ecosystem management. We use Phillip Island, Australia, as a case study to investigate the impacts of two invasive species management options and consider whether a critically endangered mammal is likely to establish a population in the presence of invasive species. Qualitative models are used to determine the effects of apex predator removal (feral cats) and invasive prey removal (rabbits, rats, and mice). We extend this approach using Ensemble Ecosystem Models to consider how suppression, rather than eradication influences the species community; and consider whether an introduction of the critically endangered eastern barred bandicoot is likely to be successful in the presence of invasive species. Our analysis revealed the potential for unintended outcomes associated with feral cat control operations, with rats and rabbits expected to increase in abundance. A strategy based on managing prey species appeared to have the most ecosystem‐wide benefits, with rodent control showing more favorable responses than a rabbit control strategy. Eastern barred bandicoots were predicted to persist under all feral cat control levels (including no control). Managing ecosystems is a complex and imprecise process. However, qualitative modeling and ensemble ecosystem modeling address uncertainty and are capable of improving and optimizing management practices. Our analysis shows that the best conservation outcomes may not always be associated with the top‐down control of apex predators, and land managers should think more broadly in relation to managing bottom‐up processes as well. Challenges faced in continuing to conserve biodiversity mean new, bolder, conservation actions are needed. We suggest that endangered species are capable of surviving in the presence of feral cats, potentially opening the door for more conservation translocations. [ABSTRACT FROM AUTHOR]

Despite the black rat being the most common invasive rat on tropical islands, little is known about habitat selection and seasonal changes in density on atolls. On Aldabra Atoll, a UNESCO World Heritage site in the Seychelles, Indian Ocean, black rats occur in all available forest types, including mangrove forest, at high densities. Mangrove forest appears to be particularly good habitat with larger recorded body sizes, larger juveniles, and in better body condition than rats trapped in ‘terrestrial’ forest. Any plans for black rat eradication on large islands with mangrove forest will be thwarted by the presence of rats in this habitat, where poison bait is unlikely to be aerially laid successfully due to tidal inundation.

Three rat species, the Norway rat, black rat or ship rat, Pacific or Polynesian rat, and the house mouse are among the most widespread and destructive invasive mammals affecting islands. Through mostly unintentional introductions by humans, these rodents occupy >80% of the major islands worldwide. As a consequence of their omnivorous diet and large incisor teeth, introduced rats are probably the invasive animals responsible for the greatest number of plant and animal extinctions on islands. The effects of house mice on island ecosystems are less well known when compared with rats. We have reviewed past diet studies of these 4 omnivorous rodent species. Our review suggests that due to the high variability in diet, as well as direct and indirect effects of predation, all 4 species pose potential threats to many plants and animals on Pacific islands. Although rodent diets greatly differ among sites, diets appear to roughly follow this pattern: Norway rats and house mice generally consume proportionally more animal than plant (Norway rats consume many vertebrates and house mice mostly consumes arthropods), whereas black and Pacific rats generally consume proportionally more plant than animal. Studies specifically linking rodent diets with the population status of surrounding biota are needed in order to clarify the effective impacts of these rodent species. Much could be learned from rodent removal experiments, which could further expand our knowledge of invasive rodent species effects, and native species conservation, on islands.

Black rats have been on Anacapa Island for close to 100 years and pose a threat to the biodiversity of the island. Removing non-native rats from an island is a powerful conservation tool. There have been numerous attempts to eradicate rats from Anacapa: 2001/2002 marked the first successful eradication of invasive rodents from an entire island where an endemic rodent was present, and the first aerial application of rodenticides in North America.

Introduced black rats are among the most invasive species to islands worldwide. In addition to agricultural impacts, rats are vectors of disease, cause damage to native flora and fauna, and negatively impact threatened/endangered species. Eradication efforts have met with mixed success. Success or failure of an eradication effort can depend on the population density of the target species, which can influence rodenticide sowing rates. We used snap trapping grids to estimate black rat densities in two different forest types on Diego Garcia: coconut forest and mixed species forest. Individual snap traps baited with fresh coconut were placed every 10 m in a 100-m × 100-m (1 ha) grid in the mixed forest and every 20 m in a 220-m × 220-m grid (4.8 ha) in the coconut forest. Traps were checked twice daily for 7 and 11 days in the mixed and coconut forest, respectively. In total, 914 rats were captured on the coconut forest grid and 125 rats were captured on the mixed forest grid. Rat density in coconut forest was 187 rats/ha (95% CI: 176-201) and 88 rats/ha (95% CI: 82-104) in mixed forest. Stomach contents were examined in 121 rats trapped in the mixed forest: 81% contained coconut along with other vegetation or meat, and 67% contained coconut exclusively. It is likely that the high rat density is driven by an abundant coconut food source resulting in a variable distribution of rats among habitat types. Planning for eradication will need to consider the variability of rodent densities across different habitats, with management strategies developed to address this variability.

Introduced rats continue to have a major impact on biodiversity around the world, and improved control techniques are required to avoid further extinctions. We are trialing re-setting toxin-delivery systems (Spitfires) targeting a range of predators, including rats. The rat Spitfire works by firing 800 mg of a toxic paste onto the belly of the rat as it passes through a tunnel; the device then resets. When the rats groom the paste from their fur, they ingest the toxin. Each Spitfire is capable of approximately 100 doses and is fitted with a counter and a delay mechanism. We trialed 0.55% 1080 paste in the Spitfire and 15 of 15 wild Norway rats and 14 of 15 black rats died. Further trials are planned with a range of toxins to allow flexibility of use. Resetting devices that are expected to work for long periods without being serviced also require long-life lures. Preliminary trials showed urine and scats from female Norway rats were attractive to both male and female Norway rats. The volatile components from these and further trials will be identified to aid in developing a long-life lure. The long-term, effective control of introduced rats will require a range of toxins with different modes of action, a number of different delivery systems, and long-life lures.

Palmyra Atoll National Wildlife Refuge is a moist Central Pacific atoll that supports one of the best remaining tropical forest ecosystems in the region, including 10 species of breeding seabirds and a robust population of the world’s largest terrestrial invertebrate, the coconut crab. Despite these riches, the atoll’s ecosystem has been modified by introduced black rats that were inadvertently brought to Palmyra during WWII. Between June 1 and 30, 2011, a partnership between the U.S. Fish and Wildlife Service, The Nature Conservancy, and Island Conservation successfully implemented a project to remove rats from Palmyra. Independent monitoring of bait application and its environmental effects was undertaken by the USDA. Over the 28-day operation, a team of 41 people from 5 countries utilized 2 helicopters, 10 slingshots, 148 bait stations, and hand spreading to strategically apply 38,561 kg of rodent bait containing the anticoagulant brodifacoum (25 ppm) to Palmyra’s 235 hectares of emergent land. Palmyra’s challenging eradication environment demanded the development of a novel approach, such as broadcast application rates between 75 and 85 kg/ha and the use of “bolas” to bait coastal forest canopy to minimize bait drift into the marine environment. Initial findings show minimal non-target impacts as a result of the project, and post-eradication monitoring has failed to detect rats. Increased recruitment by at least 2 native tree species has been observed. By removing rats from Palmyra, the partnership aims to safeguard the atoll’s indigenous flora and fauna, encourage the reestablishment of extirpated seabird species, and create an ecological refuge for species within the Central Pacific region that are at risk of extinction. This project is a conservation milestone for the Refuge, and it has established a benchmark for eradication campaigns on other tropical islands.

Between June 1 and 30, 2011, a partnership between the U.S. Fish and Wildlife Service, The Nature Conservancy, and Island Conservation successfully implemented a project to remove introduced black rats from Palmyra Atoll National Wildlife Refuge. Prior to the rat eradication, we assessed several environmental risk factors associated with the application of an anticoagulant rodenticide to Palmyra’s emergent land area. Here, we present the findings from a study of toxicant migration from bait pellets into topsoil. Topsoil from plots characterized as “sandy” or “humus” was collected after exposure to bait pellets containing 50 ppm of diphacinone or 25 ppm of brodifacoum. Brodifacoum and diphacinone were detected in samples of both sandy and organic topsoil while control samples collected outside of the study plots tested negative for both toxicants. With both toxicants, residue concentrations decreased with time and neither toxicant was detected in most of the 28, 36, and 50-day samples; trace amounts (=0.2 ppm for brodifacoum and =2 ppm for diphacinone) of the toxicants were detected in a few samples from these groupings. We did not find a significant difference in toxicant concentrations between the two types of topsoil. The results from this study suggest that following a broadcast of rodenticide across Palmyra’s emergent land area, small amounts of brodifacoum or diphacinone would migrate to, and remain in, Palmyra’s topsoil for a short period of time.

We monitored natural and artificial nests during a two-part study on East Maui, Hawaii, designed to examine factors influencing nest depredation by black and Polynesian rats. The first half of the study examined the effects of rat control on nest depredation within portions of the Hanawi Natural Area Reserve. Rat density monitoring indicated control efforts had significantly reduced black rat captures in treatment areas, but no differences in survival of artificial or natural nests between treatment and control areas were observed. The second half of the study examined the effect of nesting substrate on nest depredation in the Makawao Forest Reserve during June 2003 and June 2004. We chose fruiting and non-fruiting nest substrates for artificial nests in two habitat types, native ohia/koa forest and an adjoining forest dominated by non-native tropical ash. Results from snap trapping showed that the relative density of black rats was significantly higher in the ohia/koa forest than the tropical ash forest, but plots with more rat captures did not always have higher rates of nest depredation as predicted. Our findings suggest that there is a large degree of variability in nest depredation by Rattus spp., but that rat density, forest type, and nest substrate influence nest depredation rates.

Brown (Rattus norvegicus) and black (R. rattus sensu lato) rats are among the world's most widespread and important invasive animals; however, there are very few studies of their natural history in natural habitats within their native ranges. Both taxa are native to Japan and still occur in natural habitats there, but have been traditionally treated by zoologists working in the country as invasive pests limited to cities and agricultural lands. We used thermal imaging and snow tracking to conduct the first study of status, distribution and behavioural ecology of remnant human-independent populations of these species in Japan. We found both species still living in natural habitats away from human settlements: brown rat is a rare species in wetlands on the main islands and in upland forests on Hokkaido, while the native taxon of R. rattus species complex, the Asian house rat (R. tanezumi sensu stricto) inhabits remnant deciduous old-growth forests, as well as evergreen subtropical forests, in the south of the country. Such knowledge is critically important for understanding the rats' evolutionary history, invasion biology and behaviour. Future molecular studies should aim to clarify the origin of these populations: possibly they are Pleistocene relicts threatened by hybridisation with rats of related non-native taxa. [ABSTRACT FROM AUTHOR]

The black rat (Rattus rattus) is one of the most widespread rodents on islands worldwide, introduced over the last five centuries. However, reliable information concerning how biotic or abiotic factors influence key parameters of black rat population biology in insular contexts is currently unavailable. Here we aim to document the relative abundance of rat populations and evaluate how the age structure and the body mass of adult individual vary seasonally in different forest environments under contrasting climatic conditions. Rats were captured during wet and dry seasons in 2017–2018 at one or two sites in each of the four natural forested environments of Guadeloupe, all of which experience widely different annual rainfall (semi-deciduous dry forest, seasonal evergreen forest, mountain rainforest and Pterocarpus officinalis swamp forest). A total of 171 black rats were captured during a 1018 trap-night effort. Overall capture results confirm this species to thrive in all the natural forested environments we investigated. With the exception of the P. officinalis swamp forest, black rat populations reach higher relative abundances during the wet season due to juvenile and sub-adult recruitment at the end of the dry season. In contrast, in the P. officinalis swamp forest, breeding activity continues during both seasons and relative rat abundance appears to fluctuate less seasonally. The relative abundance of adult black rats is also higher in the seasonal semi-evergreen and rainforests that experience little or no water stress. These contexts therefore appear the most favourable for sustaining black rat populations, a pattern that is most likely connected to a combination of climatic and/or edaphic parameters that condition the year-round availability and abundance of food resources. [ABSTRACT FROM AUTHOR]

The black rat Rattus rattus and the house mouse Mus musculus are two commensal rodent species that harbour and shed zoonotic pathogens, including helminths. The aim of this survey was to study the helminth community and the patterns of infections in R. rattus and M. musculus from two Mayan communities in Mexico. Gastrointestinal helminths were isolated from 322 M. musculus and 124 R. rattus , including Gongylonema neoplasticum , Hassalstrongylus aduncus , Hassalstrongylus musculi , Hydatigera taeniaeformis metacestode, Hymenolepis diminuta , Nippostrongylus brasiliensis , Oligacanthorhynchidae gen. sp., Syphacia muris , Syphacia obvelata , Rodentolepis microstoma and Trichuris muris. The overall richness of helminths was seven in R. rattus and six in M. musculus. The results of generalized linear models showed that juvenile rodents had lower probabilities of being infected with G. neoplasticum , H. taeniaeformis and H. musculi than adult rodents. A positive association between the prevalence of S. muris and rat abundance was found. The intensity of infection with S. muris was higher in the rainy season than in the dry season; the opposite result was found for H. musculi infection. Male R. rattus harboured more S. muris specimens. The intensity of infection with T. muris was inversely associated with mouse abundance. The presence of the zoonotic H. diminuta , as well as H. taeniaeformis and R. microstoma in rodent populations indicates that there is risk of transmission, and that their entire life cycle occurs in the study area. [ABSTRACT FROM AUTHOR]

Objective is to study the role of small mammals, habitant in the Republic of Guinea, in Lyssavirus circulation. Materials and methods. Investigations were conducted using RT-PCR; nucleotide sequence of Lyssavirus cDNA fragments was identified with the help of sequencing with further phylogenetic analysis. Results and conclusions. Tested have been 356 brain samples from small mammals for the presence of Lyssavirus RNA using RT-PCR with genus-specific primers. The animals were caught in the suburbs of Kindia city in 2016. The samples were obtained from wild animals pertaining to Rodentia, Chiroptera, Eulipotyphla, and Carnivora orders.Lyssavirus RNA was detected in 31 samples (8.7 %). For 14 PCR positive samples the appurtenance to Lyssavirus was confirmed through identification and analysis of nucleotide sequences of the collected short cDAN fragments of viral genome. The presence of rabies virus RNA in positive tests was excluded from PCR with the help of species specific primers. The pool of samples from black rats, Rattus rattus, positive for Lyssavirus RNA, contained RNA characteristic of Mokola lyssavirus species. Specified has been nucleotide sequence of matrix protein M gene fragment of Mokola virus. Genetic material of Mokola virus was detected in the Republic of Guinea for the first time ever.

A field study was conducted to disclose the prevalence of different helminth parasites in the black rat, Rattus rattus, in some regions of Stara Zagora district, Bulgaria. Out of 67 examined rats, 53 (79.1%) were found to be positive. Helminths of three classes were detected such as Cestoda: Hymenolepis diminuta (47.8%), Hymenolepis nana (43.3%), Taenia taeniaeformis larvae (7.5%), Taenia polyacantha larvae (1.5%); Secernentea: Syphacia obvelata (4.5%), Aspiculuris tetraptera (3.0%) and Adenophorea: Capillaria hepatica (9.0%), Trichuris muris (3.0%). Of all the investigated rats, 27 (40.3%) were infected by one helminth species and 26 (38.8%) by more than one. Hymenolepis diminuta was a predominant species in cases of single infections (23.9%). The most frequent co-infections were observed by H. nana and H. diminuta (16.4%).

Wesselsbron disease is a neglected mosquito transmitted Flavivirus infection that causes abortions and has teratogenic effects on sheep and cattle in Africa. Human can also be infected. The detection of human or animal cases is complicated by the non-specific symptoms close to Rift Valley Fever (RVF) in domestic livestock species or Dengue like syndrome in humans. Then, these detections are usually made during RVF investigations in sheep. These domestic animals should take a role in the life cycle of the virus but some evidences of Wesselsbron virus (WSLV) presence in wild animals suggest that the latter may be involved in the virus maintenance in nature. However, the reservoir status of wild vertebrate in general and rodents particularly for WSLV is only based on an isolation from a Cape short-eared gerbil in southern Africa. Most of WSLV isolations are from southern parts of Africa even if it has been found in western and central Africa or Madagascar. In Senegal, there are serological evidences of WSLV circulation in human since the 1970s and some isolations, the last one of which dates back in 1992. Despite the detection of the virus on mosquitoes until the 2000s in different parts of the country, no new human case has been noted. In this paper, we report the WSLV re-emergence in eastern Senegal in 2013 with 2 human cases and its first isolation from a black rat Rattus rattus. Sequencing analyses show the circulation of the same strain between these humans and the commensal rodent. The putative impact on WSLV transmission to human populations could be more important if the reservoir status of the black rat is confirmed. Focused survey in human populations, specific entomological and mammalogical investigations would permit a better understanding of the life cycle of the virus and its impact on public health.

Brown rats (Rattus norvegicus), roof rats (Rattus rattus), and house mice (Mus musculus) are considered to be important pests on livestock farms. Although the diel activity patterns of rodents are key to their control, information on this aspect of their ecology is limited. Furthermore, the effect of carnivores on rodent activity patterns as well as the carnivore species present on livestock farms is unclear. Here, we set camera traps in an open-type cow barn and in an enclosed pig barn on the same livestock farm in Japan from August through October 2021. The only rodents observed in both barns were roof rats, and the carnivore species observed were dogs (Canis familiaris), cats (Felis catus), and Japanese weasels (Mustela itatsi). Roof rats showed different patterns of activity and behavior between the barns. However, because the pattern in both barns was nocturnal, the activity patterns of roof rats and carnivores showed a moderate to high degree of overlap. Therefore, roof rats did not appear to shift their activity patterns to avoid nocturnal carnivores. Taken together, the present study provides valuable information for rodent control on livestock farms in Japan., (© 2024 The Author(s). Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.)

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 × 0.09–0.14 mm in size and had a thin (0.8–1.3 μm) 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 1.3 μm 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. [ABSTRACT FROM AUTHOR]

India is the origin to the world's most notorious invasive mammal, the black rat Rattus rattus. All previous empirical phylogeographic studies were based on very few samples originating from India-creating a paucity of data to extrapolate from. In this first specific phylogeographic study of R. rattus attempted in India, samples were obtained from 18 localities within peninsular India with a focus on the East and West coasts, regions that spread commensal R. rattus globally. The displacement loop (D-loop) and the cytochrome b (Cytb) gene were sequenced in 45 R. rattus individuals. Maximum likelihood analysis was used to assign individuals to lineages. Coalescence and Bayesian methods were employed to estimate population genetic parameters, phylogeny and divergence respectively. The phylogeography of R. rattus was elucidated by constructing median joining networks by combining newly generated D-loop and Cytb gene sequences in the current study with available sequences in the database. Our findings provide key insights into the origin, expansion and migration patterns of the black rat in India, Eurasia and in the Indian Ocean region. The study reconfirms India as the centre of origin to the global R. rattus population and identifies the Gangetic region and East coast as focal points of ancestral R. rattus populations in India. Our newly generated data provide genetic evidence in support of the origin of commensalism in R. rattus in the ancient Indus Valley region and the further spread of these commensal house rats by medieval Arab sailors in the Indian Ocean and the Mediterranean. [ABSTRACT FROM AUTHOR]

The paper summarizes all available information on the black rat (Rattus rattus) occurrence in South Bohemia. Both archaeozoological and zoological data are reviewed. The first record of the black rat in South Bohemia dates back to the late 14th century. Bones of at least six individuals were discovered during archaeological excavation of a non-functional well in the town hall of České Budějovice. The rodent was present there also during the period of mid-15th - early 16th century, as evidenced by finding of the osteological remains of at least two black rats in a waste midden. The other possible medieval locality of the black rat is the Netolice town, where a single bone was collected. The uncertainty of dating is due to the archaeological context, when much younger period is also an option. During the 20th century the black rat mummies were discovered in a house in Český Krumlov town and in a mill nearby České Budějovice. The mummified individuals were dated back to the 18th century and the forties or fifties of the 20th century, respectively. In the 19th century an undated stuffed specimen of the black rat from the Nové Hrady town was stored in the house of Schwarzenberg natural history collections. Whereas voucher specimens for recent occurrences are either lost or dubious, the medieval black rat bones are preserved in the Prachatice Museum and the Museum of South Bohemia in České Budějovice. As there are no records of the black rat in South Bohemia since the 1950s, the species is presumed extinct here. [ABSTRACT FROM AUTHOR]

Background: Rattus norvegicus (brown rat) and Rattus rattus (black rat) are known carriers of bacteria, viruses, and parasites of zoonotic and veterinary importance. Moreover, rats may play a role in the transmission of muscle larvae of the zoonotic nematode Trichinella spiralis to farm animals. We aimed to study the intestinal and intramuscular helminths in wild rats from three different environments to assess the relevance of rats as carrier of zoonotic parasites for public health. Materials and methods: Wild brown rats (117 individuals) and black rats (44 individuals) were captured at farms, in suburban and in rural environments in the Netherlands. Intestinal helminths were isolated and identified morphologically. Artificial digestion was used to isolate muscle larvae. Results and discussion: Morphological analysis of rat intestinal contents yielded six nematode species (Syphacia muris, Heterakis spumosa, Aonchotheca murissylvatici, Trichuris muris, Nippostrongylus brasiliensis, and Strongyloides sp.), three cestode species (Hymenolepis diminuta, H. nana and Hymenolepis (=Rodentolepis) fraterna), and four trematode species (Plagiorchis muris, Plagiorchis proximus, Echinostoma chloropodis, and Notocotylus imbricatus).Black rats at farms displayed the lowest intestinal helminth species variation (six species) and carried overall on average 0.93 species simultaneously. In comparison, brown rats at farms carried seven helminth species and 1.91 species simultaneously. Brown rats from suburban environments displayed the highest species variation (11 species) at 1.82 simultaneous helminth species. Absence of trematodes from rats at farms may suggest limited exchange of rats between farms and surrounding wet rural environments. We report four species of veterinary (Syphacia muris) or zoonotic relevance (Hymenolepis diminuta, Hymenolepis nana and Plagiorchis muris). We did not find Trichinella muscle larvae, consistent with long-term prevalence in Dutch wild rats.

The susceptibility of eight rodent species to a range of widely used and candidate rodenticides was determined in laboratory feeding tests. No choice and choice tests were used to assess toxicity and effect on palatability of the rodenticides to Meriones shawi (Shaw's gerbil), Arvicanthis niloticus (Nile rat), Acomys cahirinus (Egyptian Spiny mouse), Mastomys natalesis (Multumammate rat), Sigmodon hispidus (Cotton rat), Rattus exulans (Polynesian rat), and R. rattus (Ship rat) which responded differently to each chemical. The results of these tests suggest possible rodenticides suitable for control of each species. Field trials are now needed to assess the effectiveness of these compounds under practical conditions.

In view of resistance reported to have developed towards second generation anticoagulants and the problem of bait shyness and neophobia when acute rodenticides are used, it becomes imperative that methods be evolved to overcome these problems. Attempts to potentiate anticoagulants for effective rodent control is a new concept with very few studies. Experiments using two non-steroid ant-inflammatory drugs, namely ibuprofen and phenylbutazone at 80 mg/kg and 50 mg/kg body weight respectively to potentiate the action of two second generation anticoagulants, brodifacoum and bromadiolone, yielded positive results for Rattus rattus. The drugs reduced the lethal dose required for 100% mortality as well as days to death. Field trials confirmed laboratory findings.

Black rats (Rattus rattus) have begun occupying a new habitat in recent years —the Jerusalem pine (Pinus halepensis) forests in Israel. In this, otherwise almost sterile habitat, the sole source of nourishment for the rats is the pine seems that can only be extracted from the cones through a complex feeding technique. Adult black rats unfamiliar with the technique (termed "naive") were unable to attain it either through trial and error or through observational learning when housed with experienced rats (termed "strippers"). In contrast, black rat pups raised by stripper mothers did learn the pine cone opening behaviour. In addition to the presence of a stripper model, however, the clues of the pine seeds themselves, as well as partially open cones, may also play a role in the acquisition of the technique. The state of the cone itself, when encountered by the rat pups, may be an important factor. Three groups of experimental animals were used: 25 pups born to naive mothers and reared on rat chow without exposure to either stripping mothers or partially opened cones; 25 pups born to naive mothers and exposed to pine cones in various stages of opening; 55 pups born to stripper mothers and exposed both to pine cones and to the presence of their mothers actively involved in stripping the cones and feeding on the seeds. We found that pine cone stripping behaviour is learned through two stages of a local enhancement effect: First, the pups are directed to the pine cones as a food resource, and then to the cone's proximal end as a starting point. The development of the stripping technique is acquired individually, with accumulating experience.

This work compares object replacement and object presentation as causes of avoidance (new object reaction or neophobia). The movements of wild black rats, Rattus rattus, living in an automated plus maze were recorded (1) after replacing a familiar object (in a familiar place) with a series of novel objects, (2) after presenting a novel object in a familiar place where there had been no object. Replacing one object by another did not delay entry to the maze arm containing it. In contrast, the presence of a new object in a previously empty arm did increase the latency of the first approach (new object reaction), although after the first entry, the rate of visiting the arms and the time spent in them, which are measures of subsequent approach, were unaffected. Hence, this form of neophobic behavior was evoked only by the presence of a new object where none had been before. Differences with earlier reports can be resolved in most cases when attention is paid to the difference between presentation and replacement.