Editorial: trends in urban rodent monitoring and mitigation: improving our understanding of population and disease ecology, surveillance and control

Editorial on the Research Topic
Editorial: Trends in Urban Rodent Monitoring and Mitigation: Improving Our Understanding of Population and Disease Ecology, Surveillance and Control

The urban environment is unique among earth’s ecosystem in that it is almost entirely created, maintained, and modified by humans. As such, it is not often a focus of ecological research ( Dyson et al., 2019 ). However, a number of wild animals thrive in urban centers, particularly rodents. Indeed, certain species of rodents are so well-adapted to close cohabitation with people that they are rarely found in habitats devoid of their human counterparts ( Aplin et al., 2003 ). These so-called commensal rodents can be found in almost every corner of every city on earth ( Lund, 1994 ) and humans are more likely to interact with them than any other wildlife species.

Unfortunately, these interactions can lead to a diverse array of negative consequences. For example, urban rodents carry a number of zoonotic pathogens associated with significant human morbidity and mortality ( Himsworth et al., 2013 ). Exposure to rodents may also impact mental health, particularly among marginalized populations ( Lam et al., 2018 ). Finally, urban rodents consume and contaminate food stuffs, damage property and infrastructure, start fires and result in significant expenditures on pest control ( Feng and Himsworth, 2014 ). Over half of the world’s population currently live in urban centers ( United Nations, 2018 ), and given increasing rates of urbanization, these issues are likely to increase in the future. Unfortunately, there are a number of significant gaps in our understanding of urban rodents which impede our capacity to adequately prepare for current and future threats ( Parsons et al., 2015 ).

There are several reasons for the prevailing knowledge gaps ( Traweger et al., 2006 ; Banks et al., 2014 ). Many urban rodents are inherently difficult to study as they are nocturnal, secretive, and reside in habitats not readily accessible to researchers (e. g., deep within infrastructure) ( Parsons et al., 2015 ). They disproportionately populate impoverished neighborhoods ( Himsworth et al., 2013 ; Feng and Himsworth, 2014 ) where residents are disempowered to deal with rodent-related issues compared to those living in more affluent areas ( Lam et al., 2018 ). Many societies have negative associations with rodents ( German and Latkin, 2016 ) and property owners may keep infestations secret because of shame, fines or possible business closures ( Pimentel et al., 2005 ; Parsons et al., 2017 ).

Counter intuitively, the fact that humans have so much exposure to urban rodents may be responsible for the fact we know so little about them. Specifically, it is commonly assumed that because urban rodents are omni-present, scientists and authorities already understand all there is to know about them ( Parsons et al., 2016 ). This attitude is compounded by a plethora of scientific literature based on laboratory rodents—animals that are so dramatically different from their wild counterparts that extrapolation is virtually impossible ( Stryjek and Pisula, 2008 ; Puckett et al., 2018 ). Additionally, decision makers may be apathetic regarding urban rodents owing to a perception that infestations and related harms are inevitable, and attempts to address them fruitless. Finally, a lack of substantive gains regarding urban rodent-related issues may be related to the fact that the responsibility for these issues is not easily assigned to any one sector or discipline. This has resulted in a siloed approach in which gains are made in specific areas (such as pest-control techniques), without moving the field of urban rodent research forward as a whole ( Parsons et al., 2016 ).

We consider our special topics issue as a global “ call to action” for researchers to help address these gaps and barriers through fresh, innovative, and multidisciplinary approaches. Therefore, in preparing this issue, we have brought together authors and reviewers from a wide array of field and laboratory-based disciplines (genetics, ecology, pest management, social sciences, public health) and from countries around the world (Australia, Brazil, Canada, Finland, France, Germany, Hungary, Japan, Netherlands, New Zealand, Poland, and the United States) to share as many ideas and perspectives as possible. From the resulting set of manuscripts, a number of critical themes emerged.

The research presented here paints a compelling picture of the complex interactions between rats and the urban environment. For example, Minter et al. show that within a specific neighborhood, the features of the urban built environment (i. e., variations in land use and building disrepair) did not significantly impact Leptospira spp. carriage in rats ( Rattus spp.). However, variation in infection dynamics among cities suggested that broader features of the urban ecosystem impact pathogen ecology. Minter et al. found that although lethal rat control can produce a temporary decrease in the risk of Leptospira spp. infection in humans, only permanent and significant environmental modification was capable of producing a significant and sustained impact. The impact of the environment extends beyond Leptospira spp., with Cummings et al. showing that the distribution of newly identified influenza A virus in rats was significantly influenced by the urban microenvironment (e. g., parks vs. residential areas) and season.

Banks, P. B., Bytheway, J. P., Carthey, A. J., Hughes, N. K., and Price, C. J. (2014). “ Olfaction and predator-prey interactions amongst mammals in Australia,” in Carnivores of Australia: Past, Present and Future , eds A. S. Glen and C. R. Dickman (Collingwood, VIC: CSIRO Publishing), 389.

Dyson, K., Ziter, C., Fuentes, T. L., and Patterson, M. S. (2019). Conducting urban ecology research on private property: advice for new urban ecologists. J. Urban Ecol. 5: juz001. doi: 10. 1093/jue/juz001

Feng, A. Y., and Himsworth, C. G. (2014). The secret life of the city rat: a review of the ecology of urban Norway and black rats ( Rattus norvegicus and Rattus rattus ). Urban Ecosyst. 17, 149–162. doi: 10. 1007/s11252-013-0305-4

German, D., and Latkin, C. A. (2016). Exposure to urban rats as a community stressor among low-income urban residents. J. Community Psychol. 44, 249–262. doi: 10. 1002/jcop. 21762

Himsworth, C. G., Feng, A. Y., Parsons, K., Kerr, T., and Patrick, D. M. (2013). Using experiential knowledge to understand urban rat ecology: a survey of Canadian pest control professionals. Urban Ecosyst. 16, 341–350. doi: 10. 1007/s11252-012-0261-4

Lam, R., Byers, K. A., and Himsworth, C. G. (2018). Beyond zoonosis: the mental health impacts of rat exposure on impoverished urban neighborhoods. J. Environ. Health 81, 8–11.

Lund, M. (1994). “ Commensal rodents,” in Rodent Pests and Their Control , eds A. P. Buckle and R. H. Smith (Oxfordshire: CAB International), 23–43.

Parsons, M. H., Banks, P. B., Deutsch, M. A., Corrigan, R. F., and Munshi-South, J. (2017). Trends in urban rat ecology: a framework to define the prevailing knowledge gaps and incentives for academia, pest management professionals (PMPs) and public health agencies to participate. J. Urban Ecol. 3: jux005. doi: 10. 1093/jue/jux005

Parsons, M. H., Sarno, R., and Deutsch, M. (2015). Jump-starting urban rat research: conspecific pheromones recruit wild rats into a behavioral and pathogen-monitoring assay. Front. Ecol. Evol. 3: 146. doi: 10. 3389/fevo. 2015. 00146

Parsons, M. H., Sarno, R. J., and Deutsch, M. A. (2016). A detailed protocol to enable safe-handling, preemptive detection, and systematic surveillance of rat-vectored pathogens in the urban environment. Front. Public Health 4: 132. doi: 10. 3389/fpubh. 2016. 00132

Pimentel, D., Zuniga, R., and Morrison, D. (2005). Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecol. Econ. 52, 273–288. doi: 10. 1016/j. ecolecon. 2004. 10. 002

Puckett, E. E., Micci-Smith, O., and Munshi-South, J. (2018). Genomic analyses identify multiple Asian origins and deeply diverged mitochondrial clades in inbred brown rats ( Rattus norvegicus ). Evol. Appl. 11, 718–726. doi: 10. 1111/eva. 12572

Stryjek, R., and Pisula, W. (2008). Warsaw Wild Captive Pisula Stryjek rats (WWCPS)-establishing a breeding colony of Norway Rat in captivity. Polish Psychol. Bull. 39, 67–70. doi: 10. 2478/v10059-008-0011-x

Traweger, D., Travnitzky, R., Moser, C., Walzer, C., and Bernatzky, G. (2006). Habitat preferences and distribution of the brown rat (Rattus norvegicusBerk.) in the city of Salzburg (Austria): implications for an urban rat management. J. Pest Sci. 79, 113–125. doi: 10. 1007/s10340-006-0123-z

United Nations (2018). 68% of the World Population Projected to Live in Urban Areas by 2050, Says UN. United Nations Department of Economic and Social Affairs. Available online at: https://www. un. org/development/desa/en/news/population/2018-revision-of-world-urbanization-prospects. html (accessed August 2, 2019).