Anopheles gambiae s.l. swarms trapping as a complementary tool against residual malaria transmission in eastern Gambia

Abstract

Malaria remains a major health problem and vector control is an essential approach to decrease its burden, although it is threatened by insecticide resistance. New approaches for vector control are needed. The females of Anopheles gambiae s.l. mate once in their life and in the swarms formed by males. Trapping swarms of Anopheles gambiae s.l. males is a potential new intervention for vector control, alternative to the use of insecticides, as it would disrupt mating . The proof-of-concept pilot study aiming at investigating swarm trapping as a potential vector control intervention, was carried out in 6 villages as in eastern Gambia. Swarms of Anopheles gambiae s.l. were identified and their size, height, and duration determined during the baseline year. Swarm trapping by local volunteers was implemented the following transmission season in 4 villages while the other 2 villages were taken as controls. Entomological outcomes were monitored by Human Landing Catches and Pyrethrum Spray Catches. A cross-sectional survey to determine malaria prevalence was carried out at the peak of the malaria transmission season for two consecutive years. At baseline, 23 swarming sites of Anopheles gambiae s.l. were identified. Before the intervention, mean indoor resting density per house and malaria prevalence were similar between control and intervention villages. Following the intervention, Anopheles gambiae s.l. indoor resting density was 44% lower in intervention than in control villages (adj IRR: 0.0.56; 95% CI 0.47–0.68); the odds of malaria infections were 68% lower in intervention than in control villages (OR: 0.32; 95% CI 0.11–0.97). Swarm trapping seems to be a promising, community-based vector control intervention that could reduce malaria prevalence by reducing vector density. Such results should be further investigated and confirmed by larger cluster-randomized trials.

Characterization of the swarming behavior of Anopheles coluzzii and Anopheles gambiae (Diptera: Culicidae) populations in a hybrid zone of Senegal

“…Our results showed that swarms were always initiated by 1 or 2 males displaying a tortuous flight pattern as found in other studies (Charlwood et al 2002, Diabate et al 2003, 2009, Assogba et al 2014, 2022, Sawadogo et al 2014). During swarming, females approach swarms to select a mating partner then leave the swarm with the selected male in copula (Diabate et al 2003, 2009).…”

“…Indeed, studies in Benin have shown the association between indoor resting density and swarm size (Assogba et al 2014). However, the same pattern of small swarming size with low indoor resting density was found in The Gambia (Assogba et al 2022), a bordering country of Senegal and close by this study areas. Therefore, more research is needed to further characterize factors likely influencing the swarm size and the potential contribution of indoor resting density.…”

Multisensory integration in Anopheles mosquito swarms: The role of visual and acoustic information in mate tracking and collision avoidance

“…Our findings offer compelling evidence that mosquitoes actively process and integrate visual and acoustic information, a discovery that has implications for both ecological research and public health initiatives, particularly in the context of vector control. Notably, previous interventions targeting male mosquito swarms have been linked to reduced female insemination rates and decreased malaria prevalence, highlighting the potential of swarm-based interventions in vector management ( 8 , 78 ). Yet, the practical application of this strategy has been often limited by reliance on insecticides or labor-intensive manual trapping methods.…”