A comparison of the attractiveness of flowering plant blossoms versus attractive targeted sugar baits (ATSBs) in western Kenya

Abstract

Attractive Targeted Sugar Baits (ATSB) have been demonstrated to result in significant reductions in malaria vector numbers in areas of scarce vegetation cover such as in Mali and Israel, but it is not clear whether such an effect can be replicated in environments where mosquitoes have a wide range of options for sugar resources. The current study evaluated the attractiveness of the predominant flowering plants of Asembo Siaya County, western Kenya in comparison to an ATSB developed by Westham Co. Sixteen of the most common flowering plants in the study area were selected and evaluated for relative attractiveness to malaria vectors in semi-field structures. Six of the most attractive flowers were compared to determine the most attractive to local Anopheles mosquitoes. The most attractive plant was then compared to different versions of ATSB. In total, 56,600 Anopheles mosquitoes were released in the semi-field structures. From these, 5150 mosquitoes (2621 males and 2529 females) of An. arabiensis, An. funestus and An. gambiae were recaptured on the attractancy traps. Mangifera indica was the most attractive sugar source for all three species while Hyptis suaveolens and Tephrosia vogelii were the least attractive plants to the mosquitoes. Overall, ATSB version 1.2 was significantly more attractive compared to both ATSB version 1.1 and Mangifera indica. Mosquitoes were differentially attracted to various natural plants in western Kenya and ATSB. The observation that ATSB v1.2 was more attractive to local Anopheles mosquitoes than the most attractive natural sugar source indicates that this product may be able to compete with natural sugar sources in western Kenya and suggests this product may have the potential to impact mosquito populations in the field.

Characteristics of the Western Province, Zambia, trial site for evaluation of attractive targeted sugar baits for malaria vector control

“…Trees appear to be the main source of sugar production. Mangifera indica (mango trees) and Senna siamea (evergreen trees) are predominant in the trial site and are known to be attractive to Anopheles gambiae [ 8 ]. Herbaceous plants that are known to be attractive to mosquitoes and are also common in the study site include Bidens pilosa (Blackjack), Senna occidentalis (coffeeweed) , Manihot esculenta (cassava) and Ipomoea batatas (sweet potato) (see Supplementary file 1 for the full information).…”

Deployment of attractive targeted sugar baits in western Zambia: installation, monitoring, removal, and disposal procedures during a Phase III cluster randomized controlled trial

“…Although it is known that ATSB stations in good condition remain efficacious throughout a seasonal deployment in this context [ 18 ], it is not known if threats to physical integrity, including holes/tears and presence of mold, may be associated with reduced product efficacy (e.g., due to reductions in product attractancy and vector feeding). Cage and semi-field studies using the Sarabi ATSB v1.2 in Kenya suggest that mold may not be a major deterrent to Anopheles mosquito attractancy and feeding on the bait station [ 19 ]. Further research may be warranted to identify with greater specificity the thresholds with which mold and holes/tears are associated with reduced efficacy in a field setting.…”