Abstract
BackgroundIrrigated agriculture is key to increase agricultural productivity and ensure food security in Africa. However, unintended negative public health impacts (e.g. malaria) of such environmental modification have been a challenge. This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia.MethodsAnopheline mosquito larvae were surveyed from two agroecosystems, ‘irrigated’ and ‘non-irrigated’ areas during the dry (December 2017–February 2018) and wet (June 2018–August 2018) seasons. Mosquito habitat diversity and larval abundance were compared between the irrigated and non-irrigated areas. The association between anopheline mosquito larvae occurrence and environmental parameters was analysed using Pearson chi-square. Multiple logistic regression analysis was used to determine primary parameters that influence the occurrence of anopheline larvae.ResultsOverall, 319 aquatic habitats were surveyed during the study period. Around 60% (n = 152) of the habitats were positive for anopheline mosquito larvae, of which 63.8% (n = 97) and 36.2% (n = 55) were from irrigated and non-irrigated areas, respectively. The number of anopheline positive habitats was two-fold higher in irrigated than non-irrigated areas. Anopheline larval abundance in the irrigated area was 16.6% higher than the non-irrigated area. Pearson’s chi-square analysis showed that season (χ2 = 63.122, df = 1, P < 0.001), agroecosystem (being irrigated or non-irrigated) (χ2 = 6.448, df = 1, P = 0.011), and turbidity (χ2 = 7.296, df = 2, P = 0.025) had a significant association with larval anopheline occurrence.ConclusionsThe study showed a higher anopheline mosquito breeding habitat diversity, larval occurrence and abundance in the irrigated than non-irrigated areas in both dry and wet seasons. This indicates that irrigation development activities contribute to proliferation of suitable mosquito breeding habitats that could increase the risk of malaria transmission. Incorporating larval source management into routine malaria vector control strategies could help reduce mosquito population density and malaria transmission around irrigation schemes.
Highlights
Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa
This study aims to assess the impact of large scale irrigation on the malaria vector mosquitoes larval breeding and abundance
Among the surveyed larval habitats, 80.6% (n = 257) were positive for mosquito larvae and anopheline mosquito larvae were found in 59.1% (n = 152) habitats (Table 1)
Summary
Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa. This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia. The distribution of malaria is mainly governed by the spatial and temporal distribution of malaria vectors in different ecological settings. Environmental modifications such as construction of irrigation schemes could alter the existing ecological setting and favor breeding of mosquitoes by providing additional aquatic habitats [5]. Such environmental changes may lead to the change in mosquito vector diversity, distribution, abundance and proliferation. Identifying the source of mosquitoes helps decision makers to implement tailor-made mosquito vector interventions
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