Germain Gil Padonou

Malaria and dengue fever are transmitted by female mosquitoes of the Anopheles and Aedes genera, respectively. These diseases are among the most prevalent

The Plasmodium transmission-blocking endosymbiont Microsporidia MB was previously identified in Anopheles gambiae s.l., but its association with the carria

Insecticidal pressure on Anopheles gambiae sensu lato populations has contributed not only to the selection of physiological resistance mechanisms but also

Aedes mosquitoes are major vectors responsible for the transmission of arboviral diseases. This study aimed to identify the types of breeding sites colonized by Aedes mosquitoes and to assess the epidemic risk of arboviral diseases across communes in Benin. From January to November 2024, mosquito larvae were collected in nine study communes. All water-holding containers encountered were inspected for larvae and pupae. Samples of larvae and pupae were collected, pooled by breeding site type, and reared to adulthood for species identification. The frequency of different breeding site types was recorded. Epidemic risk was assessed using the House, Container and Breteau indices. Aedes aegypti (70.7%) was the most abundant species, followed by Culex quinquefasciatus (25.3%). Breeding sites were mainly artificial and included domestic containers (buckets, jars, drums, cans, cisterns, water troughs), tyres, and discarded containers (tin cans). The House, Container and Breteau indices indicated a high epidemic risk of arboviral diseases across the communes. The wide diversity of breeding sites supporting Aedes development, coupled with the high epidemic risk indices, highlights the urgent need for integrated vector control strategies, with priority given to identified high-risk areas.

Background: As next-generation insecticide-treated nets (ITNs) are increasingly deployed, it is essential to monitor their durability over time under operational conditions to support evidence-based procurement and replacement strategies by national malaria programs. This study evaluated the insecticidal durability of next-generation ITNs distributed in Mozambique through the New Nets Project (2020–2022), with a focus on bioefficacy and chemical content over 24 months of household use. Methods: An ITN insecticidal durability study was conducted with nets from four districts of Mozambique to evaluate four ITN product types: pyrethroid-only (MAGNet ^® , DuraNet ^® , Olyset ^® Net), pyrethroid-PBO (Olyset ^® Plus), pyrethroid-pyriproxyfen (Royal Guard ^® ), and pyrethroid-chlorfenapyr (Interceptor ^® G2). ITNs were withdrawn from households at 6, 12, and 24 months post-distribution. Bioefficacy was assessed via WHO cone and tunnel bioassays using insecticide-susceptible and pyrethroid-resistant laboratory strains of Anopheles gambiae s.l., and through experimental hut trials in Cove, Benin against wild, pyrethroid-resistant An. gambiae s.l. populations. Chemical analysis was conducted to quantify active ingredient content over time. Results: The pyrethroid components of all ITN types retained high efficacy, with 100% of nets meeting WHO bioefficacy criteria at 6, 12, and 24 months in bioassays using the susceptible An. gambiae KISUMU strain. However, the proportion of Olyset ^® Plus nets meeting WHO thresholds in bioassays assessing the bioefficacy of the PBO component against the pyrethroid-resistant An. gambiae s.l. AKRON strain, declined from 73% at 6 months to 40% at 24 months. Royal Guard ^® showed variable performance for pyriproxyfen bioefficacy, with pass rates increasing from 43% to 87% over the same period. Interceptor ^® G2 maintained high bioefficacy against the pyrethroid-resistant VKPER strain, with ≥92% of nets meeting WHO efficacy criteria across all time points. Experimental hut trials confirmed the superior field performance of Interceptor ^® G2 compared to pyrethroid-only nets, though mortality declined from 55% to 39% and blood-feeding inhibition from 72% to 19% between 6 and 24 months. Chemical analysis showed substantial degradation of PBO and chlorfenapyr by 24 months, with residual levels at 8% and 32% of baseline, respectively. Conclusion: Next-generation ITNs provide improved protection against pyrethroid-resistant malaria vectors, but the durability of their enhanced efficacy varies by active ingredient. Interceptor ^® G2 demonstrated the most consistent performance over 24 months, reinforcing its utility for control of pyrethroid resistant malaria vectors. However, declining personal protection and insecticide content underscore the need for long-term monitoring. These findings support the implementation of extended, context-specific durability studies to guide ITN selection, replacement strategies, and policy decisions for sustained malaria control.

Background: This study conducted in the departments of Oueme and Plateau aims to assess the presence of the dengue virus and its different serotypes in Aedes aegypti and Aedes albopictus , as well as the epidemic risk incurred by the populations. Methods: Collections of adult mosquitoes using human landing catches (HLC) were carried out in six communes, three (Porto-Novo, Adjarra, and Avrankou) in the Oueme department and the rest (Ifangni, Kétou, and Pobè) in the Plateau department. Pools of ten Aedes mosquitoes were formed, and stored at −80°C in RNA later. RT-PCR was used to detect dengue virus, and conventional PCR for the different serotypes. Inspection of water containers and collection of Aedes larvae was performed inside and around each house to calculate the stegomyan indices. Results: In the six communes, the dengue virus was present both in Ae. aegypti and Ae. albopictus . Combined data of the two Aedes species at the communes level revealed infection rates ranging from 80.00% (95% CI: 61.43–92.29) to 96.67% (95% CI: 82.78–99.92). In all the communes, the values of stegomyan indices reached the WHO threshold, which indicates the existence of the risk of an arbovirus epidemic. In addition, the infection rates were similar for Ae. aegypti [88.19% (95% CI: 81.27–93.24)] and Ae. albopictus [86.79% (95% CI: 74.66–94.52)]. The three virus serotypes detected in the pools of Aedes were DENV-1, DENV-3, and DENV-4, with a high prevalence for the first two. Conclusion: This study revealed that three serotypes (DENV-1, DENV-3, and DENV-4) of dengue virus circulate in Ae. aegypti and Ae. albopictus in the departments of Oueme and Plateau. Moreover, the risk of transmission of arboviruses was globally high and variable from commune to commune. This information is essential for informed decision-making in the preventive control of the disease.

Updated information on the distribution and abundance of Aedes aegypti and Aedes albopictus is crucial to prepare African countries, such as Benin, for possible arboviral disease outbreaks. This study aims to evaluate the geographical distribution, abundance and biting behaviour of these two vectors in Benin. Three sampling techniques were used in this study. The collection of Aedes spp. adults were made through human landing catch (HLC), immatures were captured with the use of ovitraps, and a dipping technique was used for the collection of Aedes spp. in 23 communes located along the North–South and East–West transect of Benin. Adult Aedes mosquitoes were collected indoors and outdoors using HLC. Mosquito eggs, larvae and pupae were collected from containers and ovitraps. The adult mosquitoes were morphologically identified, then confirmed using a polymerase chain reaction (PCR). Overall, 12,424 adult specimens of Aedes spp. were collected, out of which 76.53% (n = 9508) and 19.32% (n = 2400) were morphologically identified as Ae. aegypti and Ae. albopictus, respectively. Geographically, Ae. aegypti was found across the North–South transect unlike Ae. albopictus, which was only encountered in the southern part of the country, with a great preponderance in Avrankou. Furthermore, an exophagic behaviour was observed in both vectors. This updated distribution of Aedes mosquito species in Benin will help to accurately identify areas that are at risk of arboviral diseases and better plan for future vector control interventions.

The efficacy of a vector control tool in reducing mosquito biting is crucial for its acceptability. The present study compared the vector density of Culex spp. And Mansonia spp. across clusters, which received two dual-active ingredient (a.i.) long-lasting insecticidal nets (LLINs) and a standard pyrethroid-only LLIN, and assessed the seasonality of these mosquito genera. A total of 85,723 Culex spp. and 144,025 Mansonia spp. were caught over the study period. The density of Culex and Mansonia was reduced in all three arms over the study period. There was no evidence of a significant reduction in the indoor or outdoor density of Culex spp. in either dual-a.i. LLIN arm as compared to the standard pyrethroid-only net arm. A similar trend was observed with Mansonia spp. A high density of Culex spp. was found both in rainy and dry seasons, while for Mansonia spp., this was mainly observed during the rainy season. These results suggest that the novel insecticides in the dual-a.i. LLINs did not have an additional impact on these species and that pyrethroids might still be effective on them. Further work is required to determine whether these species of mosquitoes have resistance to the insecticides tested in this trial.

The main objective of the present study is to assess the preferences in terms of vertebrate hosts of Anopheles coluzzii, the main malaria vector in the pastoral area of Malanville, Benin, where rice cultivation and livestock are the main source of income for the populations. Adult mosquitoes were collected through pyrethrum spray catch, and human landing catch in two communes in Benin: Malanville, a pastoral area, and Porto-Novo, a nonpastoral area. Molecular species identification was performed through PCR within the Anopheles gambiae complex. Blood meal origin and P. falciparum sporozoite infection were determined using ELISA blood meal and circumsporozoite protein tests, respectively. Overall, 97% of females of An. gambiae s.l. were An. coluzzii, with biting behavior more pronounced outdoors in the pastoral area. In Malanville, the main vertebrate hosts on which females An. coluzzii blood fed were goats (44%), humans (24.29%), bovines (22%), and pigs (1.4%). Our results also showed that single-host blood meals (human: 24.29% or animal: 68%) were mostly observed compared to mixed blood meals (8.58%). The human biting rate (HBR) and P. falciparum sporozoite rate (SR) of An. coluzzii were 66.25 bites/man/night and 0.77%, respectively. However, in the nonpastoral zone (Porto-novo), 93.98% of samples were An. coluzzii. The latter blood-fed mostly (86.84%) on humans, with an estimated HBR of 21.53 b/m/n and SR of 5.81%. The present study revealed an opportunistic and zoophagic behavior of An. coluzzii in the Malanville area with an overall low mean SR.

Background Updated information on the distribution and abundance of Aedes aegypti and Aedes albopictus is crucial to prepare African countries like Benin for possible arbovirus outbreaks. This study aims to evaluate the geographical distribution, the abundance, and the biting behaviors of these two vectors in Benin. Methods Three sampling techniques (Human Landing Catch (HLC), Larval sampling, and Ovitrapping) were used to collect both immature and adult stages of Aedes spp in 23 communes located along the North-South and East-West transect of Benin. Adult Aedes mosquitoes were collected indoors and outdoors using HLC. Mosquito eggs, larvae, and pupae were collected from containers and ovitraps and morphologically identified, then confirmed by Polymerase Chain Reaction (PCR). Results Overall, 12,428 adult specimens of Aedes spp, out of which 76.53% (n = 9508) and 19.32% (n = 2400) were morphologically identified as Ae. aegypti, and Ae. albopictus respectively. Geographically, Ae. aegypti was encountered across the North South transect unlike Ae. albopictus which was only encountered in the southern part of the country, with a strong preponderance in Avrankou and Ifangni. Furthermore, exophagic behaviors were observed in both vectors. Conclusion This updated distribution of Aedes mosquitoes in Benin will help to accurately identify areas at risk of arboviruses, to better plan future vector control interventions.