Prevention or poisoning? Dilemmas in urban rats control (original) (raw)
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Population responce of rodents to control with rodenticides
We summarize theoretical approaches and practice of rodent pest control in Russia and former USSR during last 50 years. We review literature as well as original data to understand mechanisms of rodent populations recovery after chemical control campaigns in urban areas, agricultural lands and natural foci of plague. Laboratory and field experiments indicate that inherent individual variation in behavioural, physiological and life-history traits provides survival of heterogeneous mix of individuals in residual population with increased resistance to poisonous baits and high reproductive potential that leads to fast recovery of a population. In a series of field experiments with various rodent and lagomorph species (Mus musculus, Rattus norvegicus, Meriones unguiculatus, M.meridianus, M.tamariscinus, Ochotona pallasii) we have shown that patterns of recolonization of depopulated area and mechanisms of population recovery vary among species and depend on species-specific social organization. After control territorial and group-living species demonstrated an increase in mobility and affiliative and marking behaviour and a decrease in intraspecific aggression. The rate of recolonization of treated areas was high due to redistribution of survived individuals and immigration by neighbors. Population recovered to original level due to increased breeding performance and fecundity of both survived residents and immigrants. In contrast, socially-independent species exhibited minor changes in behaviour. Recolonization was mainly due to better survival and recruitment of youngs, so the rate of recolonization was low. Species-specificity of behavioural compensation mechanisms to control should be considered when developing ecologically based rodent management strategies.
Liquid Fertility Management Bait Uptake by Urban Rats within New York City Subway Refuse Rooms
Proceedings of the Vertebrate Pest Conference, 2014
Traditional rodent management tools, such as traps and lethal rodenticides, are acute measures to reduce commensal rodent populations. Given the growing concerns regarding effectiveness, environmental safety, and animal welfare related to these tools, it has become imperative to find new methods. Fertility control is an emerging potential alternative to these tools as a safe, humane and effective method of long-term population management. SenesTech, Inc. has developed a liquid fertility management bait that causes follicle depletion in the ovaries of female Sprague Dawley rats and compromises sperm production in male Sprague Dawley rats in laboratory settings. These studies have shown significant decreases in litter sizes following bait consumption, but acceptance of this bait by wild rodents needed to be confirmed. Bait acceptance was tested within refuse rooms of the New York City subway system. Bait was provided ad libitum for 90 days. Uptake was evaluated by examining, via fluorescence microscopy, the presence of the bait marker rhodamine B, which manifests as fluorescent bands in whiskers. Presence of these bands indicated that 51% of the captured population had consumed the bait, and of these, 58% had taken the bait more than once. These results demonstrate that wild rats will consume a liquid fertility management bait, even in the presence of highly palatable and abundant food within the refuse rooms. This study establishes the successful acceptance of a bait by wild rats. Further investigation is needed to evaluate the effectiveness of this product for the management of urban Norway rat populations.
PLoS ONE, 2014
Norway and black rats (Rattus norvegicus and Rattus rattus) are among the most ubiquitous urban wildlife species and are the source of a number of zoonotic diseases responsible for significant human morbidity and mortality in cities around the world. Rodent ecology is a primary determinant of the dynamics of zoonotic pathogens in rodent populations and the risk of pathogen transmission to people, yet many studies of rat-associated zoonoses do not account for the ecological characteristics of urban rat populations. This hinders the development of an in-depth understanding of the ecology of ratassociated zoonoses, limits comparability among studies, and can lead to erroneous conclusions. We conducted a year-long trapping-removal study to describe the ecological characteristics of urban rat populations in an inner-city neighborhood of Vancouver, Canada. The study focused on factors that might influence the ecology of zoonotic pathogens in these populations and/or our understanding of that ecology. We found that rat population density varied remarkably over short geographical distances, which could explain observed spatial distributions of rat-associated zoonoses and have implications for sampling and data analysis during research and surveillance. Season appeared to influence rat population composition even within the urban environment, which could cause temporal variation in pathogen prevalence. Body mass and bite wounds, which are often used in epidemiologic analyses as simple proxies for age and aggression, were shown to be more complex than previously thought. Finally, we found that factors associated with trapping can determine the size and composition of sampled rat population, and thus influence inferences made about the source population. These findings may help guide future studies of rats and rat-associated zoonoses. Citation: Himsworth CG, Jardine CM, Parsons KL, Feng AYT, Patrick DM (2014) The Characteristics of Wild Rat (Rattus spp.) Populations from an Inner-City Neighborhood with a Focus on Factors Critical to the Understanding of Rat-Associated Zoonoses. PLoS ONE 9(3): e91654.
The Rationale for Culling of Rodent Litters. Agnish, N. D., and
1996
Based on a review of the pertinent literature and our own unpub-lished data, it is recommended that culling of rodent litters in the early postnatal period should be a standard practice in delivery-type reproduction studies. This, in turn, will reduce the litter size-induced variability in the growth and development of pups during the postnatal period and thus increase the sensitivity of statistical analyses to detect treatment-related effects. This will also ensure that any adverse effects on pup growth (body weight gain) and development (reflex and behavior development) are not masked by a treatment-induced reduction in Utter size. The culling should be carried out randomly and no attempt should be made to selec-tively cull sick or underweight pups. Since male pups weigh sig-nificantly more than females and studies have shown differences in maternal behavior toward one sex over the other, whenever possible each culled litter should consist of an equal number of males and females, ...
Population genetics and genotyping as tools for planning rat management programmes
Journal of Pest Science, 2018
Brown rats are a prolific synanthropic pest species, but attempts to control their populations have had limited success. Rat population dynamics, dispersal patterns, and resistance to rodenticides are important parameters to consider when planning a control programme. We used population genetics and genotyping to investigate how these parameters vary in contrasting landscapes, namely one urban and two rural municipalities from eastern France. A total of 355 wild brown rats from 5 to 6 sites per municipality were genotyped for 13 microsatellite loci and tested for mutations in the Vkorc1 gene which confers resistance to some rodenticides. Results revealed a strong genetic structure of the sampled rat populations at both regional (between municipalities) and local (between sites within municipalities) levels. A pattern of isolation by distance was detected in the urban habitat and in one of the rural municipalities. GeneClass and DAPC analyses identified 25 (7%) and 36 (10%) migrants, respectively. Migrations occurred mostly between sites within each municipality. We deduced that rat dispersal is driven by both natural small-scale movements of individuals and longer-distance (human-assisted) movements. Mutation Y139F on gene Vkorc1 was significantly more prevalent in rural (frequency 0.26-0.96) than in urban sites (0.00-0.11), likely due to differences in selection pressures. Indeed, pest control is irregular and uncoordinated in rural areas, whereas it is better structured and strategically organised in cities. We conclude that simultaneous pest control actions between nearby farms in rural habitats are highly recommended in order to increase rat control success while limiting the spread of resistance to rodenticides.
BJHS Themes, 2017
During the period from 1919 to 1970, rat killing was ‘modernized’: official, scientific, commercial, agricultural and county advisers sought ‘rat control’. Scientific expertise on rat parasites and rat control circulated internationally. The risks posed to human health through plague, as traced by researchers who were already expert on the third pandemic, led in the UK to the Rats and Mice (Destruction) Act 1919; and the United Nations Conference on Food and Agriculture, at Hot Springs, Virginia, USA, 1943 informed its replacement, the Prevention of Damage by Pests Act 1949. Anticoagulants such as Warfarin developed in the USA at first sold widely in the UK, then later British research on resistance informed subsequent American research. This UK application of international policy and science paralleled the emergence of an official case at Parliamentary level for the national, multidisciplinary and multi-agency approach to rats. Within the UK, animal ecologists under Charles Elton m...
Frontiers in Ecology and Evolution, 2022
To sustainably control urban rat infestations, management efforts need to encompass large areas of urban centers. Therefore, the objective of this review and narrative synthesis was to collate what is known about municipal-scale rat management. We explored the management frameworks that have been used at a large scale in cities and we describe the expectations of experts who have designed and implemented these frameworks. We found that there has been a persistent “war on rats” paradigm driving this literature since the early 1900s. Not only was there little quantitative evidence to support this paradigm and associated methodologies, but together, they failed to meet the expectations of those who designed and implemented them due to real-world constraints (i.e., limited resources). To improve the field of municipal management, we identify two distinct options. First, stakeholders may continue to wage the “war on rats” while improving existing strategies within this paradigm. Key path...
2005
In the present paper the feeding experiment with laboratory rats, conducted at the Ludwig Boltzmann Institute for Biological Agriculture from 1987-1989 is described in more detail to show the advantages, but also the difficulties of the method (Velimirov et al. 1992). Two groups of rats (Long Evans strain), each consisting of 20 pairs, were fed with products from organic resp. conventional growing systems. After chemical analyses of all products, vitamins, minerals and trace elements were added if needed to provide nutritionally balanced diets. With 2 harvests 3 generations (6 litters) were investigated. In the first litters significantly fewer offspring were born dead or died within the first week of their lives. The survival rate until weaning time at the age of 28 days and the weight development were slightly more successful. The weight gain of the female rats in connection with litter size and pup weight during lactation was significantly higher. But the change from the feed mix...
2020
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...