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Observed series of Norway rat infestations (grey line) together with the estimated series from the model (black line).
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Urban Norway rats are challenging pests, posing significant health and economic threats. Implementing ecologically based integrated rodent management (EBIRM) programmes relies primarily on the understanding of ecological relationships between rodents and their environments, with emphasis on the processes influencing rodent populations in the target...
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Context 1
... estimated/expected series of rat infestations from the well-fitted model was the observed series for the period 2006-2008 (Fig. 3). In the diagnosis of the residuals of the model, a random distribution was observed with no autocorrelation; model residuals were also approxi- mately normally distributed (Kolmogorov-Smirnov test, P = 0.075). ...
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Citations
... Rodent activity depends on weather conditions [2,45,46]; however, in our study, observation of trapped rodents over rice planting seasons indicated that their abundance is negatively correlated with the wet season. Thitipramote [6] discovers that, even though the greater bandicoot rats have the capability to breed all year long, their breeding seasons peak during the wet planting seasons in Thailand. ...
Pest rodents significantly reduce crop yields globally each year, necessitating an efficient rodent management program. In small rice-producing nations like Malaysia, these rodents might lead to food insecurity, thus a science-based pest rodent management strategy is crucial. We attempted to identify the key habitat structure that affects rodent pest populations by investigating the relationships of rodent pest populations with farming practices, site-level habitat, and landscape characteristics. We found that rodent abundance in the rice fields was positively correlated with bund height and width. In addition, rice growing stages and planting seasons affected rodent abundance. However, rodent abundance was negatively related to the distance from active burrows to residential areas. As an alternative to chemical control, we suggest that trapping exercises with a covered trap should be conducted around active burrows located nearby residential areas, with high and wide bunds during early rice planting stages in the dry rice planting season.
... A similar study was performed in Madrid city and a district of Latina in Brazil. They assessed the possible interaction of urban rat infestations with environmental factors in the selected regions and found that Madrid city was the most problematic area regarding rat infestation (Tamayo-Uria et al., 2013). Commensal rats and mice live at human's expense, invade their home, eat their food and destroy their commodities, which derives no benefits from this relationship. ...
In the last decade there is a huge increase in the human population that has witnessed the important changes in the ecology, climate and human behaviour which ultimately favours the survival and increase in the population of urban pests. More alarmingly, a dramatic expansion in the rodent’s populations is a growing threat to the humans living in different urban settings. It is supposed that several socio-economic issues, environmental factors and type of housing facilities are contributing towards this higher increase in the rodent’s population in these areas. However, urban rat control programs are still ineffective as very little is known about their ecology. This study sought to investigate the type of housing and environment factors that provide food, water, shelter and harborage to rats and mice and risk factors of rodent infestations in three of the housing systems i.e. in squatter’s settlements, departmental colonies and posh residences including bungalows in Faisalabad. A total of 720 structures (240 each) were selected from these three housing systems. Snap and live trapping of commensal rats and mice (Rattus rattus, Rattus norvegicus,Mus musculus) was carried out fortnightly from November, 2017 to October, 2018 suspecting the rats and mice population as variable as different structured housing systems. The removal data were used to estimate the size of the population of rats and mice per system. For rat and mice population estimation, Change-in-ratio (CIR) and Regression of daily capture on cumulative captures (RR) were employed. The higher number of rats/mice (814 specimens) were collected in squatter’ settlements. Among these 560, 184 and 70 specimens were of Mus musculus, Rattus rattus and Suncus murinus, respectively. The number of rodents captured from departmental colonies and posh residences/bungalows was 210 specimens (129 of M. musculus, 71 of R. rattus and 10 specimens of S. murinus) and 30 specimens of M. musculus, respectively. The major socio-economic factors contributing to these higher rodent infestations were low-grade residences with inadequate or no building maintenance measures and higher housing densities along with heterogenous breeding sites. These higher densities of rats and mice may pose a serious disease threats to human populations as they are carriers of a number of pathogens. The findings of the present study provide the specific features of rats and mice population in concern to human residences and may help to formulate controlling strategies against these culprits.
... This indicates the importance of seasonal weather variability across the island of Sri Lankaespecially rainfallas a direct and/or indirect driver of infestation with small mammals in smallholder rice storage facilities. Rodent activity can depend on weather conditions (Uria et al., 2013;Vickery and Bider, 1981) as can population dynamics driven by food availability (Andreassen et al., 2020) synchronized by cropping seasons (Htwe et al., 2012) or other resources that are regulated by weather (Heisler et al., 2014;Imholt et al., 2011;Krebs et al., 2004). If there is a strong relation of rainfall and pest rodents accessing rice storage facilities, rainfall could be used in the future to predict rodent infestation in storage to take early action. ...
Several rodent species damage rice crops and commensal rodents cause damage to stored produce and infrastructure, hygienic problems and they can transmit zoonotic pathogens. In the first such study in Sri Lanka, we identified the main rodent and shrew species and the extent of post-harvest damage caused in rice storage facilities of smallholder farmers. Netting of rice bags was trialled as a new measure of protection. Field experiments were performed in the three main agro-ecological zones of Sri Lanka.
Five rodent species and one shrew species were captured in storage facilities. Rattus rattus, Bandicota indica and Suncus murinus were the dominant species in storage facilities. The small mammal composition was more related to season than to region. In storage, depending on region, 3.2-9.1% (mean 7.6%) of rice was lost to rodents when rice was stored indoors in unprotected polyethylene bags. Netting around bags reduced damage by 89% - equivalent to the annual rice consumption of one person per storage facility, reduced the presence of rodent droppings by 92% and the bag area damaged by rodents by 96%.
Our findings clearly show the considerable amount of damage caused by rodents to rice post-harvest across three agro-ecological zones of Sri Lanka and indicate that netting bags considerably reduces damage and contamination. This netting can be used to aid the development of an ecologically-based rodent management (EBRM) program tailored to local conditions. More detailed studies are needed to fully understand the population and breeding ecology of the relevant rodent pest species in relation to damage patterns to optimize management beyond individual structural measures.
... CS were located in flooding areas, only 3/112 (2.6%) had houses without water supply, and 43/112 (38.3%) were located in water course area. In addition, 26 The distribution of human leptospirosis cases in 2014 and 2015 in CS were assessed and presented (Fig 1), with 2/17 (11.8%) high risk areas and 9/95 (9.5%) low risk areas having leptospirosis cases. Although the proportion of cases was higher among high-risk sectors, no statistical difference was found (p = 0.08). ...
... Thus, risk factors have played a role in predisposing susceptible persons to contact with contaminated urine [13,24,25]. Records of rodent complaints received by the Zoonosis Surveillance Unit were used as proxy for local presence of rats in our study [25,26]. As expected, the majority of CS had recorded rodent complaints (72.3%). ...
Background:
Leptospirosis is considered a neglected zoonosis associated with infrastructure problems and low socioeconomic status, particularly slums. Since the disease is mainly transmitted in urban settings by rat urine, this risk factor may be important predictor tool for prompt control and effective prevention at the local level in urban endemic areas. Accordingly, the present study aimed to propose an early spatial predictor tool for human leptospirosis in urban settings, to test the methodology of molecular methods for assessing Leptospira spp. in trapped rats, and report associated environmental data.
Methodology/principal findings:
Official city records and previous study were used to select risk factors for human leptospirosis in an endemic neighborhood of Curitiba, Brazil. Neighborhood census sectors were divided in high- and low-risk areas using 12 selected factors: flood area, water supply, water course, green coverage, afforestation, sewage network, open sewage, open garbage, garbage collection, dumpster, pavement, and rodent complaints. In addition, rats were captured in pre-determined sites from January through March 2017, euthanized, and individual kidneys samples sent for molecular diagnosis. Human cases were obtained from official city records. In total, 95/112 (84.8%) census sectors were classified as low-risk to human leptospirosis. No significant statistical differences were found in human case frequencies between high and low-risk areas. Kidney samples from 17/25 (68.0%) trapped rats were positive for Leptospira spp. The main risk factors associated with rodent presence included inadequate water supply (p = 0.04), sanitary sewage (p = 0.04), unpaved streets (p = 0.04), and complaint of rodents (p = 0.04).
Conclusions/significance:
This study offers a new approach to score leptospirosis transmission risk, and to compare small areas and their heterogeneity in the same census sector of endemic areas. Environmental risk factors for Leptospira spp. transmission within the neighborhood were mainly due to differences in infrastructure and basic services. To the author's knowledge, this is the first study using Leptospira spp. in rats as predictor for human disease in an urban setting of a major city. Although the number of rats trapped was low, this methodology may be used as basis for early and effective interventions, focused on high risk areas for leptospirosis prior to human cases, and potentially reducing morbidity and mortality in low-income areas of urban settings.
... The wild rat (Rattus norvegicus norvegicus) is one of the most challenging pests, posing significant health and economic threats (Ibon et al., 2013). It is a potential carrier of several human and animal diseases. ...
The effect of ammonium nitrate at tested concentrations 0.2, 0.8, 1.2 and 2% and the bioagent Bacillus subtilis bacteria at 0.6×10 4 , 1.3×10 5 , 2.6×10 5 and 5.2×10 5 spores / ml on the survival of Rattus norvegicus rats was examined. The physico-chemical parameters of water samples which exposed to the sublethal concentration of ammonium nitrate and B. subtilis and control were determined. Also, the ileum of treated rats were analyzed after a month of the experiment using the electron microscopic techniques. The outcomes demonstrated that ammonium nitrate killed 86.66% of rats at the highest concentration, 2% after 28 days of experiment. While, the lowest concentration 0.2% did not cause any mortality till the end of the experiment. B. subtilis recorded the highest pathogenic ability against rats at the concentration 5.2×10 5 spores / ml with mortality 60% after 28 days of the experiment. But, it did not cause any death of rats at the concentration 0.6×10 4 spores / ml during the experiment period. The exposed water to Bacillus subtilis and ammonium nitrate has been changed in physico-chemical parameters and caused ulcers and damage to the ileum of the exposed rats. So, ammonium nitrate and B. subtilis represent successful agents for control wild rats.
... Other potential drivers include any activities that potentially provide resources to attract and sustain rodent populations. Density-dependent population processes and climatic changes can also influence rodent populations 42,43 ; climatic factors were linked with reports of urban Norway rats in Madrid, although reporting bias (increased likelihood of reporting during times of increased outdoor activity by residents) potentially confounded these effects 44 . For consistency with previous analyses 11 , we determined rodent presence from either physical evidence or householder response, although due to the systematic nature of our surveys it is less likely that reporting bias could explain the changes in prevalence apparent in our data. ...
Population trends for commensal rodents are the subject of interest and speculation but accurate data are rarely available. Here we report data from a 15-year systematic survey of rats and mice in English dwellings and present national-level estimates of prevalence for 1996–2010. We found evidence for peaks in prevalence of mice inside and rats around dwellings in 2002 and 2008. Models containing twelve variables relating to the dwelling and local area explained some but not all of the variation in prevalence. Older dwellings, those in rural areas, those with litter, drainage faults and pets or other animals outdoors tended to have higher levels of rodent prevalence. Regional differences were found but there were no seasonal trends apart from lower prevalence of mice during summer. Rodent prevalence was generally higher in rented (compared to owner-occupied) dwellings, although apparently not due to reduced tendency to carry out rodent control. The percentage of households having taken some form of action against active rodent problems varied according to prevalence at the national level, and therefore appropriate data on number of rodent control treatments carried out each year could likely act as a useful index of household rodent prevalence
... Some work on vertebrates, and on insect disease vector distribution in cities, has been undertaken, though most often correlative or matrix population models are used (e.g. Chaves et al. 2011; Cailly et al. 2012; Uria, Mahiques & Gras 2013; Sol et al. 2014). Likewise, several models have been applied to understand likely physiological stress experienced by humans (e.g. ...
More than 50% of the global human population lives in urban settings, which, for urban agglomerations with >1 million inhabitants, span a 30 °C range in mean annual temperature and 4000 mm annual precipitation range.
Although the biodiversity impacts of urbanization are most commonly investigated at the assemblage level, these impacts are mediated through organismal physiology and behaviour.
At the individual level, mechanistic models, which provide an explicit means to understand how organisms meet the requirements of heat, water and nutrient balance, offer a useful way to assess physiological and behavioural responses to urban environments and their consequences for population dynamics.
Physiological determinants of assemblage variation can usefully be investigated by examining entry, exit and transformation rules. These are biases in the processes that determine which individuals join or leave a population or assemblage, and processes that act on individuals, which remain part thereof.
Direct evidence for physiological adaptation (broadly construed as phenotypic plasticity, genotypic change or some interaction between them) to urban environments is remarkably limited, owing largely to low numbers of investigations, given that most studies that have been conducted reveal some form of adaptation.
A warming tolerance approach, applied to insects globally, demonstrates that transposing sampled populations to the nearest urban area reduces warming tolerance by several degrees, though this effect is on average more marked for the Southern than the Northern Hemisphere. The lowest warming tolerance is found between 30 and 35°N or S, suggesting that in the absence of mitigation, the urban heat island effect of cities here will have the most pronounced impacts on insect populations.
Physiological approaches offer a useful means for understanding the urban–rural gradient across a wide range of climatically variable settings during a period of background environmental change.
... Therefore, base information concerning factors that promote the presence of a pest species is necessary to determine the correct control measures, as well as the appropriate time and locations to implement them (Frantz and Davis 1991; Jackson 1998). In addition, these data will allow an evaluation of the possibility that these factors can be managed for preventative purposes (Childs et al. 1998; Fernández et al. 2007; Tamayo-Uria et al. 2013b). ...
... The possible differences in motivation in different CGP areas would not invalidate the analysis of variations over time, because, except in cases where the motivation varies abruptly by particular events, it could be considered constant for short periods of time. In Madrid, a similar study was performed analyzing both the temporal variations (Tamayo-Uria et al. 2013a) and spatial variations of complaints (Tamayo-Uria et al. 2013b). Special care should be taken with the conclusions obtained on the spatial analysis, because the possible effect of the fact that a greater number of complaints are expected at sites with greater abundance of people was not controlled. ...
... This result is opposite to that found in our city where low levels of rodent infestations were observed in areas with high building density related to high density of people (Tables 2 and 3). Moreover, both Bajomi (1993), Vadell et al. (2010), and Tamayo-Uria et al. (2013b) all observed seasonal cycles of abundance of rats (R. norvegicus and R. rattus) in urban areas, which were positively associated with average temperature . In the present study, the same pattern was observed . ...
Commensal rodents are some of the main vertebrate pests in urban areas; however, knowledge about factors that favor them at large scales is scarce. We studied spatial and temporal variations in rodent infestation levels at the whole city scale using the complaints of rodent sightings and questionnaire surveys to city neighbors. Demographic, socio-economic, and environmental characteristics handled with a geographic information system were evaluated as possible indicators of rodent infestation. The number of rodent sightings was lower in months with low mean temperature with two months time lag and higher in areas with high number of meat and metal industries. Rodent infestation estimated by the questionnaire survey showed spatial autocorrelation defining large areas with similar infestation levels. It decreased when the apartment density increased, while increased when the proportion of area occupied by shantytowns, the density of meat industries, and the proportion of area occupied by moderate urban development increased. Rodent control programs at the whole city level would have better results if public health pest agencies and/or governments will focus the efforts on areas with more precarious conditions as well as the industrial areas in the cold season when have lower rodent abundances.
... Squalor and fear generated by rats are embedded in human culture, encompassing medical, social and emotional dimensions. Recent developments in the field of rat-borne infections and other threats, such as allergies, injuries and psychological discomfort caused by the exposure to rats and their excreta (Bonnefoy et al. 2008), have led to a renewed interest in the environmental factors that may increase the risk of experiencing urban rat infestations (Langton et al. 2001;Traweger and Slotta-Bachmayr 2005;Channon et al. 2006;Traweger et al. 2006;De Masi et al. 2009Tamayo Uria et al. 2013), as well as those affecting the applied control measures (Patergnani et al. 2010;Mughini Gras et al. 2012). It is therefore becoming increasingly evident that urban rat infestations are the result of multiple factors that may eventually allow urban rat colonies to establish and proliferate to a level that exceeds human tolerance limits, resulting in the onset of a pest problem. ...
... Similar to previous studies (Tamayo Uria et al. 2013), the visible presence of one or more rats was considered here as an indicator of evident rat infestation, i.e. an infestation that was likely to have exceeded the average human tolerance limits beyond which rats become pests and control measures are usually reactively implemented. ...
... A comprehensive list of 31 environmental factors that could potentially influence the presence and density of rats in urban areas was obtained through an expert elicitation study (Tamayo Uria et al. 2013). Spatial (mappable) data for the study area were available for seven of these (Table 1). ...
Urban rat infestations have multifactorial causes and may result in severe public health and environmental problems, as well as heavy economic losses. The identification of putative environmental determinants of urban rat infestations and the mapping of areas prone to experiencing such infestations (hot spots) are crucial for effectively addressing intervention efforts. We investigated the associations between a selection of environmental factors and the occurrence of rat infestations in the city of Madrid, Spain. This was done by modelling 10,956 citizen-reported rat sightings from 2002 to 2008 using generalized additive models, both at municipality (Madrid) and district (Latina) levels. Increased age and density of housing, and decreased distance to vegetated areas, markets and cat feeding stations were factors associated with an increased risk of rat infestations. Risk maps for rat infestations were also developed and recurrent hot spots of rat activity were identified. Although a better fit to the data was obtained in the model for the smaller scale and possibly more environmentally homogenous study area of Latina, modelling the spatial distribution of rat sightings was useful for identifying factors associated with an increased risk of urban rat infestations, as well as for identifying hot spots of rat activity, providing local authorities with a practical tool for effectively targeting intervention efforts to high-risk situations based on the local environmental contexts.
This study aims to investigate the distribution of domestic rat (black and brown rat) infestation in selected local government areas (Abeokuta South, Abeokuta North and Odeda LGAs) in Ogun State, Nigeria based on respondent's information. One hundred and eighty (180) well-structured questionnaires were strategically administered to one hundred and eighty homes (odd number) which were represented by a respondent. The survey revealed that a large percentage of the respondents fall under the middle class (65.0%) and upper class (29.4%) socioeconomic status while the majority of the respondents live in a bungalow (58.9%). Generally, 74% of the respondents have domestic rats in their homes, while based on the LGAs, Abeokuta North (77%) has the highest form of rat infestation seconded by Odeda (75%). The lowest was recorded in Abeokuta South (73%), three times higher than the CDC baseline. The control measures for rat elimination appear in the order of poison only (36%) > poison and trap (33%) > trap only (23%). The chi-square test revealed a significant relationship between demographics, and home hygiene practices with the rat infestation (P<0.05), while the Pearson correlation revealed a moderate relationship between control measures and rat infestation (r=0.55; p<0.01). Conclusively, our investigation has revealed a high level of rat infestation across the study areas with Abeokuta North as a hotspot, significantly correlated with the studied parameters. Therefore, a combinatory use of control measures, population density control, and proper home hygiene practices must be implemented to avoid potential economic loss and disease outbreaks.
