Impacts of rodent outbreaks on food security in Asia

Abstract

Since 2007, a spate of rodent outbreaks has led to severe food shortages in Asia, affecting highly vulnerable and food-insecure families. Little has been documented about wildlife-management issues associated with these outbreaks. The aims of the present study were to synthesise what we know about rodent outbreaks in Asia, and identify important gaps in our knowledge. We compiled information from agencies of the United Nations, non-government organisations and the authors. The authors conducted site visits to areas affected by outbreaks of rodent populations, and convened an international conference in October 2009 to share knowledge. Bamboo masting is clearly implicated as the primary cause of the rodent-population outbreaks that led to severe food shortages in Mizoram (India), Chin State (Myanmar), Chittagong Hill Tracts (Bangladesh) and upland provinces of Lao PDR. In Laos, emergency food assistance was required for 85 000–145 000 people. In 2009, high rodent losses occurred also in lowland irrigated rice-based systems in the Philippines, Myanmar and Indonesia, not related to bamboo masting. Asynchronous or aseasonal growing of rice crops was a common element in these outbreaks. In the Ayeyarwaddy delta, Myanmar, 2.6 million rats were collected in 3 months through community activities; this outbreak appeared to be related to an extreme climatic event, Cyclone Nargis. There are two key features of rodent outbreaks that make the future uncertain. First, climate change and extreme climatic events will increase impacts of rodents on agricultural production. Second, there is food-security pressure in some countries to grow three crops per year. Increased cropping intensity will reduce fallow periods and create ideal conditions for rodents to breed nearly continuously. Implications of the research are as follows: (i) rodent outbreaks are a consequence of enhanced reproduction and natural mortality is of minor importance, particularly with rapidly increasing populations; therefore, we need to focus more on methods for disrupting reproduction; (ii) a stronger understanding of the ecology of pest species and community dynamics will enable ecologically sustainable management; (iii) we need landscape approaches that focus on crop synchrony, and timely coordinated community action to manage pest species and conserve desirable species; and (iv) a simple monitoring system can help implement ecologically based rodent management.

Is quantity or quality of food influencing the reproduction of rice-field rats in the Philippines?

“…Myanmar; Htwe et al 2013) or changing agricultural practices (e.g. Myanmar, Vietnam; Singleton et al 2007Singleton et al , 2010. Asynchronous or aseasonal planting of rice can provide high-quality food for rodents for longer periods of time per year and extend their breeding season.…”

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

“…This result suggests that rice fields may favour microparasite transmission and should be targeted for rodent-borne disease surveillance and rodent control. This is because even if only a small percentage of smallholder farmers are debilitated by rodent-borne diseases, this will impact not only on public health, but also on regional food security (Meerburg et al 2009;Singleton et al 2010;John 2014).…”

“…Moreover, these species most likely benefit from the ongoing human modification of habitats, which led Singleton et al (2010) to emphasise: 'rodent damage to agricultural production is a landscape problem that can be managed only by a widespread landscape approach'. These observations may apply worldwide because similar findings have been made in Brazil (Püttker et al 2008) and eastern Africa (Makundi and Massawe 2011).…”

“…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.…”

Rodent biology and management – who is outsmarting whom?

“…While the impacts of these rodent outbreaks could not be prevented, many researchers were able to gather significant new data relating to the species involved, the population dynamics of the outbreaks, and the social consequences of them. Indeed, the topic of these and other rodent outbreaks around the world was the subject of a special conference in October 2009 (Singleton et al 2010a(Singleton et al , 2010b. Several papers at the 4th ICRBM reported on the data collected and from these it was apparent that there needs to be careful analysis at a landscape scale of the phenomenon of rat 'floods' associated with bamboo flowering.…”