No. 5/2003
THE BIOECONOMICS OF CONTROLLING AN AFRICAN RODENT
PEST SPECIES
Anders Skonhoft
Nils Chr. Stenseth
Herwig Leirs
Harry P. Andreassen
Loth S.A. Mulungu
Abstract:
The paper treats the economy of controlling an African pest rodent, the
multimammate rat, causing major damage in maize production. An ecological
population model is presented and used as a basis for the economic analyses
carried out at the village level using data from Tanzania. This model
incorporates both density-dependent and density-independent (stochastic)
factors. Rodents are controlled by applying poison, and the economic benefits
depend on the income from maize production minus the costs for maize production,
fertiliser and poison. We analyse how the net present value of maize production
is affected by various rodent control strategies, by varying the duration
and timing of rodenticide application. Our numerical results suggest that,
in association with fertiliser, it is economically beneficial to control
the rodent population. In general the most rewarding duration of controlling
the rodent population is 3-4 months every year, and especially at the
end of the dry season/beginning of rainy season. The paper demonstrates
that changing from today's practice of symptomatic treatment when heavy
rodent damage is noticed to a practice where the calendar is emphasised,
may substantially improve the economic conditions for the maize producing
farmers. This main conclusion is quite robust and not much affected by
changing prices and costs of the maize production.
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