A capture-mark-recapture study was conducted in crop
fields in Morogoro, Tanzania, to investigate how the population
dynamics of multimammate field rats, Mastomys
natalensis, was influenced by the commonly practised land
preparation methods and cropping systems. Two land preparation
methods (tractor ploughing and slash and burn)
and two cropping systems (mono-cropping with maize and
inter-cropping with maize and beans) were investigated in a
Complete Randomized Design experiment with 2 · 2 factors,
and two 0.5 ha replicates per treatment. Mastomys
natalensis comprised 97.8% of the abundance of the three
rodent species captured in the study area. The slash and
burned fields had higher rodent population densities than
tractor ploughed fields (P < 0.05). Recruitment rates were
higher in the slash and burn fields than in the tractor
ploughed fields, suggesting that the former were more
favourable habitats for M. natalensis. Land preparation
methods appeared to influence the population dynamics of
M. natalensis through recruitment of new individuals in the
population and most probably survival. Apart from the
temporal changes in population density, which were
reflected in both tractor ploughed and slash and burn fields,
cropping systems (mono- and inter-crop) had little effect on
the population dynamics of M. natalensis [F(1,8) ¼ 6.50;
P > 0.05]. The study shows that land preparation methods
should be considered a component of rodent pest management
in ecologically based or integrated management
practices. In maize fields in Tanzania, the crop is most susceptible
to damage by M. natalensis in the first 2 weeks after
planting, and therefore, lower densities of rodents will result
into lower crop damage in tractor ploughed fields.
SUA - VLIR Programme