Biology subjects

Zembere, K.

Publications and source records attributed to Zembere, K..

4 recordsLinked to original sources

bioRxiv2025

Exploring the importance and preference of sugar feeding behaviour of malaria vectors in sugar plantations of southern Malawi

BackgroundReliable 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. MethodsUsing 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. ResultsOver 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. ConclusionSugar 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.

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bioRxiv2023

Small dams drive Anopheles abundance during the dry season in a high malaria burden area of Malawi

This study explores the influence of small dams on the exposure to malaria vectors during the dry season in Kasungu district, Malawi, an area recently identified as high priority for malaria interventions by the National Malaria Control Programme. Small dam impoundments provide communities with a continuous supply of water for domestic and agricultural activities across sub-Saharan Africa and are considered vital to food security and climate change resilience. However, these permanent water bodies also create ideal breeding sites for mosquitoes in typically arid landscapes. The study focuses on a specific dam impoundment and its vicinity, aiming to assess its spatial and temporal influence on indoor vector densities. Throughout May to August 2021, CDC light traps were used to measure indoor mosquito densities for two consecutive nights per month in three communities located at increasing distances from the dam (0km, [~]1km, [~]2km). Simultaneously, drone imagery was captured for each community, enabling the identification of additional standing water within approximately 400 meters of selected households. Larval sampling was carried out within the impoundment periphery and in additional water bodies identified in the drone imagery. Generalised linear mixed models (GLMMs) were employed to analyse the indoor Anopheles abundance data, estimating the effects of household structure (open/closed eaves), month, temperature, and water proximity on malaria vector exposure. Throughout 685 trapping nights, a total of 1,256 mosquitoes were captured, with 33% (412) being female Anopheles. Among these, 91% were morphologically identified as An. funestus s.l., and 5% as An. gambiae s.l. Catches progressively declines in each consecutive trapping month as the environment became drier. This decline was much slower in Malangano, the community next to the dam, with abundance being notably higher in June and July. Further, the majority of An. gambiae s.l. were caught in May, with none identified in July and August. Anopheles larvae were found both in the impoundment and other smaller water bodies such as irrigation wells in each survey month, however the presence of these smaller water bodies did not have a significant impact on adult female mosquito catches in the GLMM. The study concludes that proximity to the dam impoundment was the primary driver of differences between survey communities with the abundance in Chikhombwe ([~]1km away) and Chiponde ([~]2km away) being 0.35 (95% CI 0.19-0.66) and 0.28 (95% CI 0.16-0.47) lower than Malangano respectively after adjusting for other factors. These findings underscore the importance of targeted interventions, such as larval source management or housing improvements, near small dams to mitigate malaria transmission risks during the dry season. Further research is needed to develop cost-effective strategies for vector control within and around these impoundments.

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bioRxiv2021

The human-baited host decoy trap (HDT) is an efficient sampling device for exophagic malaria mosquitoes within irrigated lands in southern Malawi

Irrigation schemes provide an ideal habitat for Anopheles mosquitoes particularly during the dry season. Reliable estimates of outdoor host-seeking behaviour are needed to assess the impact of vector control options and this is particularly the case for Anopheles arabiensis which displays a wide range of behaviours that circumvent traditional indoor-insecticide based control. In this study we compared the Host Decoy Trap (HDT) with the Human Landing Catch (HLC) and Suna trap in a repeated Latin square design in two villages on an irrigated sugar estate in southern Malawi. Over the course of 18 trapping nights we caught 379 female Anopheles, the majority of which were identified as An. arabiensis. Overall, the HDT and HLC caught a similar number of Anopheles per night with both methods catching significantly higher densities than the Suna trap across both villages. Regardless of the density of Anopheles mosquitoes in each village the HLC and HDT demonstrated broadly similar sampling efficacy. We conclude that the HDT is an effective sampling device for outdoor host seeking An. arabiensis in southern Malawi. The presence of An. arabiensis in irrigated lands during the dry season poses a challenge for ongoing indoor vector control efforts.

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bioRxiv2020

The application of drones for mosquito larval habitat identification in rural environments: a practical approach for malaria control?

O_LISpatial and temporal trends in mosquito-borne diseases are driven by the locations and seasonality of larval habitat. One method of disease control is to decrease the mosquito population by removing habitat and/or reduce the likelihood of larvae developing into adults, known as larval source management (LSM). In malaria control, LSM is currently considered impractical in rural areas due to perceived difficulties in identifying target areas. High resolution drone mapping is being considered as a practical solution to address this barrier. In this paper, we use our experiences of drone-led larval habitat identification in Malawi to assess the accuracy and practicalities of this approach. C_LIO_LIDrone imagery and larval surveys were conducted in Kasungu district, Malawi between 2018-2020. Water bodies and aquatic vegetation were identified in the imagery using both manual methods and geographical object-based image analysis (GeoOBIA) and the performance of the classifications were compared. Larval sampling sites were characterised by biotic factors visible in drone imagery (e.g. vegetation coverage, type), and generalised linear mixed models were used to determine their association with larval presence. C_LIO_LIImagery covering an area of 8.9km2 across eight sites was captured. Characteristics associated with rural larval habitat were successfully identified using GeoOBIA (e.g. median accuracy = 0.98, median kappa = 0.96 using a standard RGB camera), with a median of 18.3% being classed as surface water, compared to 20.1% using manual identification. The GeoOBIA approach, however, required greater processing time and technical skills. Larval samples were captured from 326 sites, and a relationship was identified between larval presence and vegetation (log-OR=1.44, p=0.01). Vegetation type was also a significant factor when considering late stage anopheline larvae only. C_LIO_LIOur study demonstrates the potential for drone-acquired imagery as a tool to support the identification of mosquito larval habitat in rural areas where malaria is endemic. There are, however, technical challenges to overcome before it can be smoothly integrated into malaria control activities. Further consultations between experts and stakeholders in the fields of drones, image analysis and vector control are needed to develop more detailed guidance on how this technology can be most effectively exploited. C_LI

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