Rodent infestation poses a serious threat to smallholder farmers in both developed and developing countries where a large proportion of potential crop yield is lost. For example, in Tanzania, the average annual yield loss of maize and rice is estimated to be around 5 to 15%. In Eastern Africa, there are about 161 species of rodents; however, the major rodent pest is M. natalensis. Seasonal changes in abundance of this species are highly dependent on rainfall and in particular on the timing of the rainy season. Other rodent species that are important pests in agriculture are Arvicanthis spp, and Gerbillus spp, and they are also widely distributed over East Africa.
Management of rodent pests in eastern Africa relies mostly on use of chemical rodenticides which, however, often are applied only when damage has already occurred (and thus basically too late to have a significant effect on damage) or in contrast as part of a routine treatment (meaning that they are also applied when it is not necessary). Rodenticides used in this way are rarely economically and ecologically sustainable and currently the knowledge about rodent populations on individual farms is too limited to allow smarter approaches. Only for M. natalensis in maize in areas with a bimodal rainfall system, predictive models were developed earlier, and the Tanzanian Ministry of Agriculture successfully uses these models to preventatively initiate rodenticide-based control when outbreaks of M. natalensis can be expected.
However, there is a need to evaluate their wider applicability in other cropping systems and for other species. Ecologically based rodent management uses knowledge about the pest species’ ecology in order to reduce the damage experienced by farmers. It does not see the killing of rodents as an objective, but it does not exclude any approach, including the use of rodenticides. Obviously this requires a good knowledge of the species’ population biology and behavior. Therefore, as a first objective, the data from this study will refine the prediction models and test them over a wider area and different rodent pest species in east Africa. Specifically for irrigated rice, an alternative novel approach in E. Africa is the “community-based Trap-Barrier-System (cTBS)", basically a system where rodents are trapped in a rice field that is planted a short period earlier than the surrounding fields, and therefore attracting rodents from a much wider area than the field itself.
The system proved very successful in irrigated rice fields in SE Asia, increasing rice yields there by 10-25%. Its success depends on the population biology, behavior and movement patterns of the rodent species that cause the damage. This knowledge is still lacking for the species causing damage in rice fields in E. Africa. Therefore, the second major objective of the study is to investigate the feasibility and effectiveness of Trap-Barrier-Systems in rice fields. For both objectives, data will be collected from studies describing the rodent pest community and the involved species’ ecology as well as controlled experiments. The project’s coordination is taken care of by a research center in Tanzania where much earlier work has been done already, but then also extends its activities to an area in Uganda where serious rodent problems are reported but where local capacity to address the research is still limited.
This study will be conducted in Tanzania (Morogoro and Dodoma regions) and Uganda (along Nile River) where farmers grow maize and rice as staple food. The results from this study will be presented to the scientific community (journal articles, conference participations) but also shared with agricultural authorities and of course shareholders like small and large farms (extension leaflets, radio and TV programmes, extension workshops). The requested budget for this project is $499,160.34.
2014 – 2018
Dr. Georgies Mgode
Dr. Esther Ngadaya
Dr. Sigsbert Mkude
Mr. Charles D. Mwalimu
Bill & Melinda Gates Foundation
Amount: US $599,160