Exploring the importance and preference of sugar feeding behaviour of malaria vectors in sugar plantations of southern Malawi
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Background
Reliable tools are needed to control opportunistic outdoor biting and resting malaria vectors that remain beyond the reach of indoor targeted interventions. The attractive targeted sugar baits (ATSBs) have demonstrated effectiveness in some settings but have shown limited impact in other areas, likely due to differences in mosquito species’ preferences and the presence of competing natural sugar sources. However, these factors remain poorly understood and understudied. We evaluated sugar-feeding behaviour of Anopheline mosquitoes in a sugarcane plantation area of Chikwawa, Malawi, to generate additional field data that could enhance the efficacy and design of sugar-based vector control tools tailored for malaria endemic regions such as Malawi.
Methods
Using three collection tools, CDC Light traps; Prokopack aspirator and the barrier screen, we collected 187 adult anophelines from the Illovo sugar plantations. Collected mosquitoes were subjected to cold anthrone tests in the laboratory to assess the presence of plant sugars in their gut. Additionally, 810 adult Anopheles gambiae s.l., reared in the insectary from wild caught larvae, were exposed in an olfactory-driven choice experiment to identify the most attractive available sugar source in the area. Sugar sources included guavas, melon, bananas, mango, marula and sugarcane.
Results
Over 40% (n=74) of the collected Anopheles mosquitoes-including An. gambiae s.l., An. funestus , An. coustani and An. tenebrous were found to have fed on natural sugar sources. For the sugar attractiveness tests for An. gambiae s.l., guava was found to be twice as attractive (IRR = 1.97, 95% CI: 1.49-2.62, p < 0.001) as sugarcane (our reference fruit), followed by banana (IRR= 1.68, 95% CI: 1.26-2.24, P < 0.001), then mango, and melon (IRR= 1.49, 95% CI: 1.11-2.01, P= 0.008) and (IRR=1.45, 95% CI: 1.08-1.96, P= 0.014) respectively.
Conclusion
Sugar feeding is a key activity for Anopheles mosquitoes and presents a potential target for control efforts. In this setting with abundant sugarcane, guava was identified as the most attractive sugar source for An. gambiae s.l., followed by banana, mango, and melon, with sugarcane being the least attractive. Understanding local sugar source preferences can help tailor novel intervention strategies to specific environmental contexts.
