Population dynamics of Rattus argentiventer, Rattus losea, and Rattus rattus inhabiting a mixed‐farming system in the Red River Delta, Vietnam

Abstract

Rodent pests cause significant damage to lowland irrigated rice crops in the Red River Delta of northern Vietnam. Data from a 4‐year study were examined to look at the population dynamics of the ricefield rat, Rattus argentiventer (representing 50% of captures), the lesser ricefield rat, Rattus losea (30% of captures), and the black rat, Rattusrattus complex (9% of captures) that inhabit the irrigated mixed‐cropping system. We tested the hypothesis that these rodent species were breeding in response to the availability of high‐quality food provided by crops rather than in response to rainfall. The abundance of rodents fluctuated annually, with a main peak following the spring rice crop, and a secondary peak following the summer rice crop. There was a strong relationship between the monthly abundance of rats and rainfall, but a weak relationship between monthly rates of increase and rainfall. There were distinct peaks in breeding activity during the reproductive stages of the rice crops suggesting that changes in crop stages were more important than rainfall in this seasonal, but irrigated agroecosystem. The modal litter size for R. argentiventer was 8 (mean of 8.67±0.20 SE, range 2–16), where the mode for R. losea, was 7 (mean of 7.32±0.15 SE, range 3–14). Management of these species needs to be conducted prior to the onset of the main breeding seasons.

Parasite diversity of disease-bearing rodents of Southeast Asia: habitat determinants and effects on sexual size dimorphism and life-traits

“…The level of host habitat specialization was found to be linked to distribution range, which is in accordance with the observation that generalist species are locally abundant and have large distribution ranges (Brown, 1995). The results also showed that the variation in SSD is positively associated to habitat specialization.…”

“…The habitat specialization of Southeast Asian murine rodents is still poorly understood (Adler et al, 1999;Singleton et al, 2003;Wells et al, 2007;Morand et al, 2015a), and most studies have focused on peri-urban or agricultural areas (particularly paddy fields); (Brown et al, 2005;Singleton et al, 2010), or occasionally forested or limestone habitats from the conservation perspective (Wells et al, 2007;Rickart et al, 2011;Latinne et al, 2013Latinne et al, , 2015. Here, several rodent species were found to demonstrate high habitat specialization including as R. exulans in human FIGURE 3 | (A) Partial regression between the residuals of contrasts in spleen size in females and the residuals in centrality in habitat (controlling for the contrasts in host abundance and parasite species richness, using the model of Table 3); (R 2 = 0.38, P = 0.02).…”

Ecologically Based Management of Rodents in the Real World: Applied to a Mixed Agroecosystem in Vietnam

“…The types of crops grown and the timing of cropping were more important than rainfall in this irrigated farming system. Brown et al (2005 b ) found that adult female rodents commenced breeding at the maximum tillering stage of the spring rice crop and continued to breed throughout the summer rice crop. Breeding effectively ceased after harvest of the summer crop, with little breeding through the winter crop period.…”

“…For the purposes of this study, all small mammals (rodent and shrew species) captured were combined for analysis. The species composition of the small-mammal community was analyzed in a parallel paper as part of a study on the population dynamics and demography of rodents in mixed riceÀvegetable agroecosystems in Vietnam that focused on the two main species: R. argentiventer and R. losea (Brown et al 2005b).…”

Progress on research on rodents and rodent-borne zoonoses in South-east Asia

“…Moreover, most studies have assessed the potential impacts of rodents on agriculture or public health, and have focused primarily on peri-urban or agricultural areas (particularly rice paddy fields; Singleton 2003; Singleton et al 2003Singleton et al , 2010Brown et al 2005;John 2014). Several studies focusing on conservation biology have investigated rodents in forested or limestone habitats (Wells et al 2007;Rickart et al 2011;Latinne et al 2012Latinne et al , 2013a, but peridomestic species commonly found in households (e.g.…”