Browsing by Author "Moore, Jason"

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    Bioassays for the evaluation of the attractiveness of attractive targeted sugar bait (ATSB) against Anopheles mosquitoes in controlled semi-field systems
    (BMC, 2025-02-04) Tenywa, Frank; Kibondo, Ummi; Entwistle, Julian; Dogan, Osward; Haruna, Mapipi; Phisoo, Restuta; Moore, Jason; Machange, Jane; Haji Makame1,; Tripet, Frederic; Müller, Pie; Mondy, Mathias; Nimmo, Derric; Stevenson, Jennifer; Moore, Sarah
    Background Sugar feeding is an essential aspect of mosquito biology that may be exploited for mosquito control by adding insecticides to sugar attractants, so-called ‘attractive targeted sugar baits’ (ATSBs). To optimize their effectiveness, ATSB products need to be maximally attractive at both short and long range and induce high levels of feeding. This study aimed to assess the attractiveness and feeding success of Anopheles mosquitoes exposed to attractive sugar baits (ASBs). Method Experiments were conducted in 2 × 5 × 2-m cages constructed within the semi-field systems (SFS) at Ifakara Health Institute, Bagamoyo, Tanzania. Male and female Anopheles gambiae s.s. and An. funestus s.s. mosquitoes were exposed to either 20% sucrose or different ASB station prototypes produced by Westham Co. in either (1) no-choice experiments or (2) choice experiments. Mosquitoes were exposed overnight and assessed for intrinsic or relative olfactory attraction using fluorescent powder markers dusted over the ASB stations and 20% sucrose and for feeding using uranine incorporated within the bait station and food dye in 20% sucrose controls. Results Both male and female An. gambiae and An. funestus mosquitoes were attracted to the ASBs, with no significant difference between the sexes for each of the experiments conducted. Older mosquitoes (3–5 days) were more attracted to the ASBs (OR = 8.3, [95% CI 6.6–10.5] P < 0.001) than younger mosquitoes (0–1 day). Similarly, older mosquitoes responded more to 20% sucrose (OR = 4.6, [3.7–5.8], P < 0.001) than newly emerged Anopheles. Of the four prototypes tested, the latest iteration, ASB prototype v1.2.1, showed the highest intrinsic attraction of both Anopheles species, attracting 91.2% [95% CI 87.9–94.5%]. Relative to ATSB v1.1.1, the latest prototype, v.1.2.1, had higher attraction (OR = 1.19 [95% CI 1.07–1.33], P < 0.001) and higher feeding success (OR = 1.71 [95% CI 1.33–2.18], P < 0.001). Conclusions Data from these experiments support using ASBs v1.2.1, deployed in large-scale epidemiological trials, as it is the most attractive and shows the highest feeding success of the Westham prototypes tested. The findings indicate that future bioassays to evaluate ATSBs should use mosquitoes of both sexes, aged 3–5 days, include multiple species in the same cage or chamber, and utilize both non-choice and choice tests with a standard comparator. Background
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    Efficacy of the BiteBarrier transfluthrin emanator against susceptible and resistant malaria and arbovirus vectors in the semi-field system in Tanzania
    (bioRxiv, 2025-02-28) Maasayi, Masudi; Swai, Johnson; Muganga, Joseph; Moore, Jason; Stevenson, Jennifer; Coleman, Michael; Lobo, Neil; Moore, Sarah; Mgeni Mohamed Tambwe
    Controlling mosquito-borne diseases is increasingly challenging due to factors such as outdoor and early biting mosquitoes and logistical or behavioral barriers, particularly in displaced populations where the use and efficacy of core interventions are inadequate. This study evaluated the impact of BiteBarrier, a transfluthrin-based spatial emanator, over eight weeks of aging against multiple mosquito species in semi-field system simulating both indoor and outdoor settings. We assessed the protective efficacy using both landing rate and feeding success methods across five mosquito species, including pyrethroid susceptible Anopheles gambiae sensu stricto (s.s.) and Aedes aegypti, An. gambiae s.s. with knock down resistance (KDR), and pyrethroid resistant An. funestus and Culex quinquefasciatus with upregulation of mixed function oxidases. The results show that the feeding endpoint provides more robust estimates of protective efficacy compared to the landing endpoint. The BiteBarrier provided over 93% (95% CI: 92 - 93) protection indoors and 80% (95% CI: 78 - 81) outdoors against mosquito bites and substantial mortality 47% (95% CI: 43 - 53) indoor and 26% (95% CI: 22 - 30) outdoors, regardless of mosquito species or resistance status. Overall, the BiteBarrier shows potential as a tool for reducing mosquito bites and vectorial capacity, offering protection over at least eight weeks of use for both indoor and outdoor environments.