Rattus Argentiventer Research Articles

Specific PCR primers for rapid detection of five rat and mouse species in Java, Indonesia

Identifying rat and mouse species quickly, affordably, and accurately is crucial for effective population management, as well as for eradication or conservation purposes. However, the sheer diversity of these species poses a challenge. To address this, a molecular approach has been developed, involving the amplification of a short genetic marker from materials commonly left by the animal, such as hairs and feces. Recent available PCR primers were not suitable for the surveillance of large sample sizes. As a solution, this study designed and validated a PCR primer set capable of detecting five species of rats and mice (Mus musculus, Rattus tanezumi, Bandicota indica, Rattus tiomanicus, and Rattus argentiventer) commonly found in Java, Indonesia. The specific primers were derived from the cytochrome c oxidase subunit 1 (COI) gene, designed using the SP‐Designer V7.0 application, and validated using both in silico and in vitro methods. The validation results demonstrated that all five pairs of primers were highly specific, generated correct amplicons, and successfully detected the five distinct species present in a Javan mongoose feces sample. These findings are significantly important as they enable the effective detection of rat and mouse species and potentially provide valuable ecological insights from the field.

Impacts of rainfall and rainfall anomalies on the population dynamics of rodents in southeast Asian rice fields.

The mechanisms that regulate multi-annual population dynamics of rodent pest species of cereal crops is often unknown. Better knowledge of such aspects can aid pest management and in turn improve food security and human health. The patterns and processes of the population dynamics of Rattus argentiventer, in rice fields of Indonesia, and Rattus tanezumi, in rice fields of the Philippines were assessed in this article. The meta-analysis of trapping data over 20 years in Indonesia, and 16 years in the Philippines indicated that rodent populations in rice fields did not show a regular multi-annual pattern. Rattus argentiventer populations in Indonesia responded to less rainfall from the current year. Rattus tanezumi populations in the Philippines responded positively to both rainfall and rainfall anomaly with a 1-year time lag. Our study of long-term population data indicates that certain combinations of rainfall parameters could be useful to predict years when there is higher rodent abundance in rice fields. The key rodent pest species in rice fields in Indonesia (R. argentiventer) and the Philippines (R. tanezumi) differ, and the populations of each species respond differently to rainfall anomalies. Other factors such as crop cover and water availability may also be important and should be considered in future work. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Culprit behind the Mass Death of Mangroves: Egrets or Rats (Rattus losea)?

Mangroves play a crucial role in maintaining coastal ecological balance. This study focused on the impact of branch-breaking behavior on the mortality of Rhizophora stylosa in the Guangxi Shankou Mangrove Reserve. However, we found mangrove mortality in areas devoid of egret habitation, prompting a reevaluation of our research hypothesis. Further investigation suggested that nesting behavior was the primary cause of mangrove mortality. A comparison of the data from areas with egrets (Egretta garzetta, Ardea intermedia) and lesser rice-field rats (Rattus losea) activity indicated significant mechanical damage caused by rats to mangroves as the main cause of mortality. Additionally, we found that the biological characteristics of R. stylosa, particularly its stunted growth and recovery abilities after branch breaking, were key factors affecting its survival. These findings imply that rat-induced mortality may not occur in other less susceptible mangrove species. The results contradict assumptions regarding the impact of egret behavior and highlight the importance of the biological characteristics of R. stylosa. This offers fresh insights into mangrove conservation and management, emphasizing the need for ongoing observation and hypotheses verification. Future studies should explore the influence of lesser rice-field rats’ activity and the intrinsic characteristics of R. stylosa on the ecosystem’s long-term stability.

Molecular characterization of Cryptosporidium spp., Giardia spp. and Enterocytozoon bieneusi in eleven wild rodent species in China: Common distribution, extensive genetic diversity and high zoonotic potential

Cryptosporidium spp., Giardia spp. and Enterocytozoon bieneusi are common zoonotic pathogens in humans and animals. Although rodents are important parts of the ecosystem and common hosts for these pathogens, little is known of the distribution, genetic diversity and zoonotic potential of these pathogens in wild rodents. A total of 442 fecal samples were collected from eleven wild rodent species in three provinces of China, and analyzed for these pathogens by PCR and DNA sequencing. The infection rates of Cryptosporidium spp., Giardia spp. and E. bieneusi were 19.9% (88/442), 19.8% (75/378) and 12.2% (54/442), respectively. Altogether, 23 known Cryptosporidium species/genotypes were identified and their distribution varied among different sampling locations or rodent species. Subtyping of the zoonotic Cryptosporidium species identified two novel subtype families XVe and XVf in C. viatorum, the subtype family XIIh and a novel subtype family XIIj in C. ubiquitum, and the subtype family IId in C. parvum. Three Giardia species were identified, including G. microti (n = 57), G. muris (n = 15) and G. duodenalis (n = 3), with G. duodenalis assemblages A and G identified in brown rats in urban areas of Guangdong. In addition, 13 E. bieneusi genotypes including eight known and five novel ones were identified, belonging to Groups 1, 2, 10, 14 and 15. Within nine genotypes in the zoonotic Group 1, common human-pathogenic genotypes D, Type IV, PigEbITS7 and Peru8 were detected only in brown rats and Lesser rice-field rats in urban areas of Guangdong. Apparent host adaptation and geographical differences were observed among Cryptosporidium spp., Giardia spp. and E. bieneusi genotypes in wild rodents in the present study. Furthermore, the zoonotic Cryptosporidium species and E. bieneusi genotypes commonly found here suggest a high zoonotic potential of these pathogens in wild rodents, especially in brown rats in urban areas. Hygiene and One Health measures should be implemented in urban streets and food stores to reduce the possible direct and indirect transmission of these rodent-related pathogens.

Parasite infestation patterns differ between ticks and chigger mites on two rodent host species in Taiwan.

Parasites are typically concentrated on a few host individuals, and identifying the mechanisms underlying aggregated distribution can facilitate a more targeted control of parasites. We investigated the infestation patterns of hard ticks and chigger mites on two rodent species, the striped field mouse, Apodemus agrarius, and the lesser ricefield rat, Rattus losea, in Taiwan. We also explored abiotic and biotic factors that were important in explaining variation in the abundance of ticks and chiggers on rodent hosts. Ticks were more aggregated than chiggers on both rodent species. Factors important for the variation in parasitic loads, especially biotic factors, largely differed between ticks and chiggers. Variation partitioning analyses revealed that a larger proportion of variation in chiggers than in ticks can be explained, especially by abiotic factors. If, as proposed, the higher number of parasites in males is due to a larger range area or immunity being suppressed by testosterone, when A. agrarius males host more ticks, they are expected to also host more chiggers, given that chiggers adopt a similar host finding approach to that of ticks. Instead, the similar abundance of chiggers in male and female A. agrarius implies that a large home range or suppressed immunity does not predispose males to inevitably host more parasites. More variations were explained by abiotic than biotic factors, suggesting that controlling practices are more likely to be successful by focusing on factors related to the environment instead of host traits. Our study indicated that the extent of parasitism is rarely determined by a sole factor, but is an outcome of complex interactions among animal physiology, animal behavior, characteristics of parasites, and the environments.

Tyto alba Cultivation in Balinese Cultural Perspective

Rat infestation (Rattus argentiventer) in Subak Pagi and Subak Bengkel, Tabanan regency, Bali has resulted in rice crop failure in both areas. Rice production decreased drastically to only about 10 - 20% of normal conditions. The utilization of Tyto alba as a biological control of rat pests, turns out to be able to play a very effective role in controlling pest attacks. In nature, Tyto alba population continues to decline due to hunting and agricultural land clearing. This research aims to study the cultivation of Tyto alba, especially from a cross-generational cultural perspective. Generations are grouped by year of birth with a range of 20 years, from 1960 - now, into generations X, Y and Z, respectively. The research used descriptive qualitative method, through depth interview approach and forced field analysis. The results showed that there are four supporting factors for the cultivation of Tyto alba as a rat pest control, namely first Tyto alba is very effective in controlling rat pests. Another supporting factor is that Tyto alba has actually been known for a long time by the people in the two subak and has a belief value system in the life of the subak community, as well as environmentally friendly and able to maintain the food chain. There are four inhibiting factors in Tyto alba conservation efforts, namely, the lack of committed breeding officers, availability and management of food, land for preservation and development and very limited financial support. Analysis forced field concludes that, cross-generational public perception in the acceptance of Tyto alba as a biological control of rat pests is very positive. However, preservation efforts with a breeding system cannot be done in both subak at this time. Efforts to preserve and develop Tyto alba are carried out by releasing it in nature with conservation protection through village regulations.

Rat composition and population in mature oil palm adjacent to paddy field

Rat is one of the main pests in an oil palm plantation, impacted at various types and stages of oil palm growth. Ungkaya estate has a historical & endemic infestation of rats, especially in several fields adjacent to paddy fields. This study aimed to find out the seasonal migration of rats from paddy fields to oil palm fields in Ungkaya Estate. Five plots were used for trapping, identifying rat species, monitoring of rat population, rat damage intensity, and rat habitat preference at each stage of the paddy season. Trapped rats were identified as Rattus tiomanicus (56.91%), Rattus argentiventer (36.17%), and Rattus tanezumi (6.91%). The intensity of rat damage to the palm was high during the vegetative phase of paddy season and the full moon phase. The regression analysis results showed that the number of trapped rats has a positive relationship to rat damage intensity for the vegetative and harvesting stage at full moon. The number of trapped R. argentiventer at vegetative stage was higher than the generative & harvesting phase of the paddy season. Moreover, there were rat footprints observed on the riverside leading to the oil palm field. The results of all observation parameters concluded that there was seasonal migration of rats between the oil palm fields and the paddy fields in Ungkaya estate. The information is pivotal in drawing up suitable mitigation measures to control and minimize rat damage to the oil palm.

Feed Preference Tests of Carbohydrate, Protein, and Rodenticide to Tree Rat, House Rat, and Rice Field Rat

Rats are wild animals that coexistence with humans. The losses caused by these rats are damage to house building, agriculture, and plantation. Knowledge of the feed as bait and lure is very important in rat control, particulary with rodenticides and traps. The aim of this research was to find out feed preference to three species of rats and effect of feed availabili-ty toward rodenticide consumption. Tree rat (Rattus tiomanicus), house rat (R. tanezumi), and rice field rat (R. argentiventer) were tested with four stages i.e. (a) type of carbohydrate sources, (b) type of protein sources, (c) combination of carbohydrate and protein, and (d) carbohydrate, protein, and rodenticide. The method used was choice test. Carbohydrate tested were corn, rice, unhulled rice (grain), and oat. Protein were cricket, frog, fish, and mouse. Rodenticide (brodifacoum 0.005%) was tested to the rat. Each feed and rodenticide are weighed before and after testing to analyze the preference of rats. The data analyzed using SAS program for windows version 9.0, a further test with Duncan multiple range test with α = 5% and 1%. Unhulled rice (grain) and cricket were the kind of feed that most preferred or highest palatable by test animals. The existence of feed causes the lower consumption of brodifacoum rodenticide by three species of rats.

Inundation Sewers and Mapping the Prevalence Leptospirosis Throughout Rats in Central Java Province

Leptospirosis is a public health threat in countries with tropical climates, like Indonesia. Incidents in Central Java Province are still found every year and still threaten the local community. The goal of this study is to find out what connection there is between sewer puddles and mice that have found leptospira bacteria that can cause leptospirosis in the Regencies of Klaten, Sukoharjo, Karanganyar, and Boyolali in Central Java Province. This research uses descriptive analysis, a cross-sectional design study, and the Geographic Information System (GIS) to carry out mapping. From the research results, it was found that the rat species that were positive for leptospira bacteria were Rattus norvegicus (31%), Rattus tanezumi (44.8%), and Rattus argentiventer (24.1%). Apart from that, only the sampling area and the presence of puddles in the gutter had significant results with the mouse PCR results with p<0.002 and p<0.03. Due to this, there are still many mice infected with leptospira bacteria in Central Java Province. For this reason, it is hoped that the public can increase awareness to always maintain a clean environment so that mice cannot breed freely. Apart from that, related agencies can carry out more monitoring of areas where leptospirosis is still endemic.

Population Distribution of Rats (Rattus argentiventer) and the Damage Intensity on Rice and Other Crops in Pleret, Yogyakarta, Indonesia

Rice field rats is one of the main pests of rice in Indonesia and other Asian countries that can cause a crop failure. The availability food sources might affect the rat foraging in the field. The research aimed to determine the distribution of rat population and their nests in the field with different crop and to examine the level of crop damage caused by rats. The research was conducted from January to April 2023 in Pleret district, Yogyakarta, Indonesia. The 1000 m2 TBS (Trap Barrier System) was installed in the middle of the 225 ha observation area to trap rats. Crop damage inside TBS was observed using a diagonal sampling method. Crop damage outside TBS was observed using the line transect method in the 4 cardinal directions with a distance of 250m, 500m, and 750m from TBS. Rat nest’s locations were mapped using GPS. The results showed that the number of rats trapped was low in the early and late stage of rice growth and peaked when the rice aged 12 weeks after planting (WAP). Rice crop damage inside TBS occurred when rice entered 12 WAP. There was no damage on rice crops around the TBS. Rats also attacked corn and sugarcane which caused heavy damage to these crops. There were 157 active holes found in 225ha observation area and they mostly were found in rice field bunds, irrigation embankments, and vacant land. This study implied that understanding the distribution of rat’s population and their nest will support the rat control.

Morphological and molecular phylogenetic characterization of Sarcocystis kani sp. nov. and other novel, closely related Sarcocystis spp. infecting small mammals and colubrid snakes in Asia

We investigated the morphology and phylogenetic relationships of novel and previously recognized Sarcocystis spp. infecting small mammals and colubrid snakes in Asia. The nuclear 18S rRNA and mitochondrial cox1 of Sarcocystis sp.1 from mangrove snakes (Boiga dendrophila) in Thailand and Sarcocystis sp.2 from a ricefield rat (Rattus argentiventer) in Sumatra were partially sequenced. Sporocysts of Sarcocystis sp.1 induced development of sarcocysts in experimentally infected rats, which showed a unique ultrastructure that was observed previously by S.P. Kan in rats from Malaysia; therefore, we describe this species as Sarcocystis kani sp. nov. Its integration into the 18S rRNA phylogeny of Sarcocystis spp. cycling between small mammals and colubrid snakes helped clarify relationships among the so-called S. zuoi-complex of molecularly cryptic species: Sarcocystis kani sp. nov., S. sp.2, S. attenuati, S. scandentiborneensis, and S. zuoi were all included in this clade. Tree topology was resolved into dichotomies congruent with the morphological disparities between the taxa. However, cox1 gene sequencing (including newly sequenced S. singaporensis and S. zamani) revealed that Sarcocystis kani, S. attenuati, and S. scandentiborneensis were identical suggesting a recent, common ancestry. To identify other distinctive features, lineage-specific molecular patterns within both genes were examined revealing that all 18S rRNA sequences of the S. zuoi – complex possess a unique, 7-nt long motif in helix 38 of domain V7 that was different in S. clethrionomyelaphis which branched off basally from the complex. Three-dimensional homology modelling of COX1 protein structure identified amino acid substitutions within the barcode area specific for the S. zuoi-complex and substantial divergence in structurally important amino acids between Sarcocystis species of snakes as definitive hosts and other lineages of the Sarcocystidae. We discuss the utility of selected genes for species delimitation of the Sarcocystis spp. under investigation, which probably evolved during recent radiations of their intermediate and definitive hosts.

The Existence of Leptospira interrogans on Rats and The Transmission Potency in Public Areas: School, Traditional Market, and Settlement in Yogyakarta

Leptospirosis is a zoonotic disease caused by bacterial infection, Leptospira interrogans. Indonesia is known for being an endemic country of this disease and Yogyakarta Special Province has become one of the regions with high cases of Leptospirosis. There was lack of information on the L. interrogans prevalence on rats at the public areas, such as school and traditional market. This research was conducted to determine and predict the potential Leptospirosis transmission in public areas, especially in schools, traditional markets,. and the settlement of Yogyakarta. Wild rats were collected from several public places (elementary schools, traditional markets, and Settlement areas) by using single live traps. The rat's blood was centrifuged to obtain the serum. The serum was tested by using immunochromatography of Leptotek Lateral Flow. The collected rats and shrews were euthanized and then identified for the species and the morphological features. Total of 27 rats (67.5%) and shrews 13 (32.5%) were collected. There were six species of collected rats, namely Rattus argentiventer, Rattus norvegicus, Rattus tanezumi, Rattus tiomanicus, and Bandicota bengalensis, while the collected shrew species was Suncus murinus. The rats and shrews from traditional market were negative with L. interrogans, however the positive results was in elementary schools (14.28%), that were from R. norvegicus and S. murinus, moreover the positive infection also showed in the settlements (57.14%), that were from R. argentiventer, R. norvegicus, and R. tiomanicus. These findings indicated that school and settlement must be a concern for the leptospirosis transmission.

Hearing Range Analysis of Rattus Argentiventer the Paddy Field Pest

Rice is the second most-grown cereal crop and one of the important staple foods in Malaysia. Seasonal rodent attacks from a family of Rattus argentiventer have shortened rice production by up to 80%. Yet, the acoustical method in controlling rodent populations is one of the topics that have not been properly explored. Under the field study radius, this study aims to analyse the hearing range of R. argentiventer under a controlled environment. Knowing a rodent’s ability to hear is essential for evaluating whether human activities, especially in terms of noise pollution, have an impact on hearing and consequently on rodent behaviour. Thirteen subjects were randomly cage-caught in the paddy field and were tested in a reward-based go/no-go procedure. Fully trained subjects were observed after acoustically exposing the subjects to a 10 kHz of pure tone less than 60 dB SPL for 25 sessions. Hearing range analysis commenced by revealing a pure tone to the fully trained subjects at low (1 kHz – 5 kHz), median (10 kHz – 40 kHz) and high (45 kHz – 80 kHz) frequencies. The results showed the subjects have sensitive frequencies at 5 kHz for low frequency, the median frequency at 25 kHz and high frequency at 45 kHz. From the sensitivity hearing results, it can be indicated that the hearing range of R. argentiventer is between 1 kHz to 55 kHz at sound levels of 60 dB. The results responded to the lack of timely response which is within an average of 5 sec and the minimum licking period at an average of 13 sec as the inaudible cut-off hearing range.

Molecular Surveillance for Vector-Borne Bacteria in Rodents and Tree Shrews of Peninsular Malaysia Oil Palm Plantations

Many human clinical cases attributed to vector-borne pathogens are underreported in Malaysia, especially in rural localities where healthcare infrastructures are lacking. Here, 217 small mammals, consisting of rodents and tree shrews, were trapped in oil palm plantations in the Peninsular Malaysia states of Johor and Perak. Species identification was performed using morphological and DNA barcoding analyses, and 203 small mammals were included in the detection of selected vector-borne bacteria. The DNA extracted from the spleens was examined for Orientia tsutsugamushi, Borrelia spp., Bartonella spp. and Rickettsia spp. using established PCR assays. The small mammals collected in this study included Rattus tanezumi R3 mitotype (n = 113), Rattus argentiventer (n = 24), Rattus tiomanicus (n = 22), Rattus exulans (n = 17), Rattus tanezumi sensu stricto (n = 1) and Tupaia glis (n = 40). Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis were detected in the small mammals with the respective detection rates of 12.3%, 5.9% and 4.9%. Rickettsia spp., however, was not detected. This study encountered the presence of both Lyme disease and relapsing fever-related borreliae in small mammals collected from the oil palm plantation study sites. All three microorganisms (Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis) were detected in the R. tanezumi R3 mitotype, suggesting that the species is a competent host for multiple microorganisms. Further investigations are warranted to elucidate the relationships between the ectoparasites, the small mammals and the respective pathogens.

OBSERVATION ON THE FRUIT DEVELOPMENT, FRUIT RIPENING AND PREFERENCE OF RATS IN DAMAGING PINEAPPLE MD2 BASED ON HORMONAL FLOWER INDUCED DAYS AND PHENOLOGY

A study was carried out to determine the preferences of rats in damaging pineapple MD2, based on hormonal induced days. Biologische Bundesantalt, Bundessortenamt and Chemische Industrie (BBCH) coding system, a phenology scale for all flowering plants, was used to describe the vegetative growth stage of MD2 pineapple in this study. The evaluation of MD2 phenology was carried out between 60 and 173 days after hormonal flower induction activity. Rat damage was studied at two growth stages, namely fruit development and fruit ripening of MD2 pineapple. The results showed that MD2 pineapple takes around 72 to 95 days to ripen from fruit development. The pineapple is best to be harvested around 140-145 days after hormonal flower induction activity or at BBCH scale 801-805. At this time, the pineapple turns from light green to yellowish green. Two species of rats, namely Rattus tiomanicus and Rattus argentiventer preferred matured fruits in between BBCH scales 800 to 805. Chemical control through rodenticide baiting campaign for rats needs to be done as early as 70-78 days after hormonal flower induction activity or before the BBCH scale 700 as best control measures. Keywords: Biologische Bundesantalt, Bundessortenamt and Chemische Industrie coding system, pineapple, rat damage.

Molecular Identification and Genetic Variation of Rattus Species From Oil Palm Plantations of Malaysia Based on Mitochondrial Cytochrome Oxidase Subunit I (COI) Gene Sequences.

Rats (Rattus species) are the most notorious vertebrate pests in Malaysian oil palm plantations. Although many studies have been conducted on Asian rats, little attention has been paid to their species composition and phylogenetic relationships in oil palm plantations in Peninsular Malaysia. We determined the mitochondrial cytochrome oxidase subunit I (COI) gene sequence (708 bp) for 216 individual rats collected from five oil palm plantations in Peninsular Malaysia. Phylogenetic analysis in conjunction with comparison with sequences from the nucleotide sequence database revealed five distinct lineages in the Malaysian oil plantations: Rattus tiomanicus, Rattus argentiventer, Rattus exulans, Rattus tanezumi, and a taxon corresponding to the Malayan house rat, which was most frequently observed (∼50%). The last taxon has traditionally been classified as a synonym of Rattus rattus (Rattus rattus diardii) or Rattus tanezumi, but our phylogenetic analysis placed it as an independent lineage, which is not particularly closely related to R. rattus or R. tanezumi, and which we refer to as Rattus diardii. The construction of the network showed that there is considerable genetic variation within the lineages of R. diardii and R tiomanicus, suggesting that these two species are native to the Malay Peninsula.

IDENTIFIKASI TINGKAT KESEHATAN PADI SAWAH DI KECAMATAN KONDA KABUPATEN KONAWE SELATAN AKIBAT SERANGAN HAMA

Rice (Oryza sativa L.) is an important food crop in developing countries including Indonesia. Lowland rice cultivation has problems in the field, especially the level of plant health. The level of plant health is determined by the disturbance and intensity of pest attacks. This study aims to determine the types of pests of lowland rice, the intensity of pest attacks and the health level of paddy rice plants. The research was conducted in the villages of Puosu Jaya, Lamomea Village and Lebo Jaya, Konda District, Konawe Selatan Regency and the Plant Protection Laboratory of the Entomology Unit, Faculty of Agriculture, Halu Oleo University Kendari. The research was conducted from October to December 2021. The variables observed were types of rice pests, intensity of damage and health level of paddy rice plants. This research uses descriptive analysis. Pests that attack paddy rice in Konda District, South Konawe Regency consist of Scirpophaga innotata, Cnaphalocrocis medinalis, Locusta migratoria, Leptocorisa acuta and Rattus argentiventer. The health level of lowland rice in Konda District, Konawe Regency due to attacks is classified as moderate to good.

The screening for anticoagulant rodenticide gene VKORC1 polymorphism in the rat Rattus norvegicus, Rattus tanezumi and Rattus losea in Hong Kong

Anticoagulants are a major component of rodenticides used worldwide, which function by effectively blocking the vitamin K cycle in rodents. The rat Vitamin K epoxide Reductase Complex (VKORC) subunit 1 is the enzyme responsible for recycling vitamin K, and five substitution mutations (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln and Leu120Gln) located in the VKORC1 could result in resistance to anticoagulant rodenticides. This study carried out a VKORC1-based survey to estimate the anticoagulant rodenticide resistance in three Rattus species (R. losea, R. norvegicus, and R. tanezumi) collected in Hong Kong. A total of 202 rats captured in Hong Kong between 2017 and 2021 were analysed. Sequencing of molecular marker cytochrome c oxidase subunit 1 (COX1) was carried out to assist the species identification, and the identities of 52 lesser ricefield rats (R. losea), 81 common rats (R. norvegicus) and 69 house rats (R. tanezumi) were confirmed. Three VKORC1 exons were amplified from individuals by PCR followed by Sanger sequencing. A total of 47 R. tanezumi (68.1%) contained Tyr139Cys mutation in VKORC1 gene, and half of them were homozygous. None of the collected R. losea and R. norvegicus were detected with the five known substitutions leading to anticoagulant rodenticides resistance, and previously undescribed missense mutations were revealed in each species. Whole genome sequencing was further carried out on some individuals, and single nucleotide polymorphisms (SNPs) were also identified in the introns. This is the first study investigating the situation of anticoagulant rodenticide resistance in the rats collected in Hong Kong. Given that the efficacy of rodenticides is crucial for effective rodent management, regular genetic testing as well as population genomic analyses will be required to both monitor the situation and understand the adaption of different rat haplotypes for integrated pest management. Susceptibility tests for individual rodenticides should also be conducted regularly to assess their effectiveness on local species.

Optimizing the capture of neophobic rice field rats in lowland Asian rice ecosystems

BACKGROUNDTrapping is a key method for monitoring small mammals and is also one of a number of methods recommended under an ecologically‐based rodent management program to control rodent pest populations. Live‐traps are widely used globally for studying small mammal populations. In Asia where rodents are major pests of rice, single capture traps typically provide low trap success. We compared the trap success between two types of live‐traps in rice fields in Indonesia and the Philippines.RESULTSMultiple‐capture traps (MCTs) in conjunction with a linear trap barrier were significantly more effective in catching rodent pest species than single‐capture traps (SCTs) in Indonesia and the Philippines. In Indonesia, MCTs captured more individuals with a mean (±SE) percent trap success rate of (15.54 ± 4.29) compared to SCTs (3.88 ± 1.58). In the Philippines, MCTs captured more species of rodents and had a significantly higher recapture rate (1.96 ± 0.79), than SCTs (0.58 ± 0.32).CONCLUSIONMultiple‐capture traps with a linear trap‐barrier were more effective for capturing Rattus argentiventer and Rattus tanezumi in rice field ecosystems compared to single‐capture traps. MCTs captured more species of rodent pests in the Philippines and recaptured more individuals of each species. These results indicate that rodent populations can be more effectively monitored and controlled by using a multi‐capture trap with barrier system than the use of single capture traps on their own. This is the first time these two trap types have been compared for use in rice ecosystems in Asia. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Short-term exposure of anticoagulant rodenticides leads to the toxin accumulation from prey (Rattus losea) to predator (Elanus caeruleus)

Rodenticides are widely used around the world since the 1950s. In Taiwan, an anti-rodent operation initiated 1977 and became a regular action annually implied by the government until 2014. This anti-rodent operation caused many animals of non-target species being exposed by rodenticides and became an environmental issue. The Black-winged Kite (Elanus caeruleus) is a small-sized diurnal raptor widely distributed in the Old World continent. Since 2000, a newly colonized population of this species occurred in Taiwan. Although the Black-winged Kites may suffer from the threats of rodenticides, the population is still growing and soon became the most abundant raptor in farmlands of Taiwan. Whether the Black-winged Kite accumulates higher anticoagulant rodenticide residues than other raptors are still unclear. In this study, liver samples of Black-winged Kites were collected from 2013 to 2016, when the detected residues of anticoagulant rodenticides increased annually. The concentration of residue rodenticide was above 0.2 ppm among 30% of the detected samples, which is the toxicity threshold concentration of other raptors. In the meanwhile, the lesser ricefield rat (Rattus losea), the most common prey of Black-winged Kites, also extended the survival period after fed on rodenticide. The longer survival days after being poisoned can enhance the predation opportunity of raptors, thus affect the accumulated rodenticides in the raptors. This study demonstrates that the Black-winged Kite has higher concentration of anticoagulant rodenticide than most other raptors, which provide the case that the raptor can quickly accumulate rodenticide residues within a short period of time.