Innovative water management for vector control: the case of rice cultivation in Burkina Faso’s Vallée du Kou

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Résumé

Background A new water-saving techniques involves minimal tillage and intermittent flooding has the advantage
of reducing the production of mosquito larvae, which could in turn reduce the density of adult mosquitoes. The aim
of this study was to evaluate the impact of a new water-saving technique on reducing the number of Anopheles
breeding sites in an area with a high density of the main malaria vector.
Methods The study was conducted in experimental rice plots measuring 5.5 × 3.0 m (16.5 m2) from February 2024
to May 2024. Three treatments were implemented: (i) deep ploughing combined with intermittent flooding (DP + IF),
(ii) minimum tillage with continuous flooding (MT + CF), and (iii) minimum tillage with intermittent flooding (MT + IF),
the latter representing a novel approach. The traditional farming system, deep ploughing with continuous flooding
(DP + CF) was used as the control for comparative analysis. Control of adult mosquitoes was conducted through systematic monitoring and elimination of swarms. To date, the performance of these techniques, whether individually
or in combination, had not been comparatively evaluated.
Results The results of this study demonstrate that minimum tillage combined with intermittent flooding significantly
reduced larval densities, by up to 80% at the transplanting stage and nearly 85% at maturation (Kruskal–Wallis test,
p-value < 0.05). The reduction was less pronounced during the tillering stage. The average density of adults collected
from houses in the intervention village fell from 3.89 mosquitoes per house in the pre-intervention phase to 1.16
mosquitoes per house in the post-intervention phase, compared with 6.62 and 6.63 in the control village. A substantial reduction of more than 85% in the mosquito population at the intervention site, Vallée du Kou 2 (VK2), compared to the control site (VK3) was observed (Fisher’s Exact Test: p-value = 0.003). A reduction in insemination status
and a shift towards younger males unable to mate was observed.
Conclusions The combination of minimal tillage with intermittent flooding and targeted swarm control substantially
reduced mosquito populations and shows promise as an integrated malaria vector control strategy

Mots-clés

Vector control, Anopheles, Malaria, Irrigation, Agriculture