Population dynamics of synanthropic rodents after a chemical and infrastructural intervention in an urban low-income community

Abstract

Synanthropic rodents are ubiquitous in low-income communities and pose risks for human health, as they are generally resistant to control programs. However, few or no studies have evaluated the long-term effect of chemical and infrastructural interventions on rodent population dynamics, especially in urban low-income communities, or evaluated the potential recovery of their population following interventions. We conducted a longitudinal study in a low-income community in the city of Salvador (BA, Brazil) to characterize the effect of interventions (chemical and infrastructural) on the dynamics of rodent population, and documented the post-intervention recovery of their population. We evaluated the degree of rodent infestation in 117 households/sampling points over three years (2014-2017), using tracking plates, a proxy for rodent abundance/activity. We reported a significant lower rodent activity/abundance after the chemical and infrastructural interventions (Z = -4.691 (p < 0.001)), with track plate positivity decreasing to 28% from 70% after and before interventions respectively. Therefore, the combination of chemical and infrastructural interventions significantly decreased the degree of rodent infestation in the study area. In addition, no rodent population rebound was recorded until almost a year post-intervention, and the post-intervention infestation level did not attain the pre-intervention level all through the study. Moreover, among pre-treatment conditions, access to sewer rather than the availability of food was the variable most closely associated with household rodent infestation. Our study indicates that Integrated Pest Management (IPM)-approaches are more effective in reducing rodent infestation than the use of a single method. Our findings will be useful in providing guidance for long-term rodent control programs, especially in urban low-income communities.

Figure 1

(A) Location of Brazil within the map of South America. (B) The distribution of the sampling points in the three valleys used in Pau da Lima. The figure (A,B) was generated using QGis Version 3.10 software. (C) Breakdown of the study timeline for rodent infestation surveys from campaign 1 to 7.

Figure 2

(A,B) An open sewer between households in the study area, (C,D) The study area undergoing environmental modification i.e. channeling of the drainage into a major junction, and the construction of community square, roadway and sidewalk. The figure photographed by Fabio Neves Souza, Institute of Biology, Federal University of Bahia, Brazil.

Figure 3

Mean with standard deviation of rodent infestation by campaign and valley (valley 1—blue, valley 2—yellow & valley 3—red colour respectively).