ABSTRACT
Rodents cause serious problems to human communities in Africa as a result of their involvement in the spread of diseases (Katakweba et al. 2012) and in the losses of crops through direct consumption (Mulungu et al. 2003; Bekele et al. 2003) and spoilage (Mdangi et al. 2013). For example, Taylor (1968) reported 20% damage to maize crop after the outbreak of rodents in Western Kenya. Earlier reports (Taylor 1968) on economic losses due to rodents in Kenya indicated 20-30% damage to maize crops, and a 34-100% loss during rodent outbreaks. In Ethiopia, it has been estimated that rodents consume up to 26.4% of maize crop in most years (Bekele et al. 2003). In Northern Ethiopia, surveyed farmers estimated 9-44% pre-harvest yield losses in annual production of cereal crops due to rodent attacks (Meheretu et al. 2010), while Central Ethiopia showed 26.4% loss of yield in maize (Bekele et al. 2003). In Tanzania, rodents are estimated to cause on average 15% yield loss (Makundi et al. 1991), which would mean the loss of around 382 673 tonnes per year of the actual yield (FAO statistics 2014). This amount of maize, with an estimated value of US$42.5 million (at US$11.1 per 100 kg bag of maize), would be enough to feed 2.1 million people for a whole year (at about 0.5 kg/day/person). However, in many parts of Africa, this figure has risen dramatically over the last few years, most noticeably in places where rodent outbreaks occur (Mwanjabe et al. 2002; Taylor and Green 1968, 1976). Today, it is not usual for smallholder maize farmers to report chronic rodent damage
of more than 80% in certain cropping seasons and localities (Mwanjabe and Leirs 1997; Mulungu et al. 2003). To overcome such problems, a sound understanding of rodent population dynamics and breeding patterns can help in the design and implementation of appropriate control strategies (Leirs et al. 1997; Singleton et al. 1999). According to Mulungu et al. (2005), there are about 31 rodent pest species involved in crop damage in Tanzania. However, the most important pest species are Mastomys natalensis, Arvicanthis spp. and Gerbilliscus spp. (Taylor and Green 1976; Fiedler 1994; Leirs et al. 1994), with M. natalensis being the most predominant rodent pest species (Leirs 1995; Mulungu et al. 2011; Massawe et al. 2012).
