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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 gambiaecomplex. Blood meal origin and P. falciparumsporozoite 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. coluzziiblood 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. falciparumsporozoite rate (SR) of An. coluzziiwere 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. coluzziiin the Malanville area with an overall low mean SR.

Pyrethroid resistance is widespread in sub-Saharan Africa. The objective of this study was to assess the insecticide resistance intensity in Anopheles gambiaes.l. (Diptera: Culicidae) in four districts of Benin in order to better understand how pyrethroid-only nets are likely to be effective. Thus, adult females of An. gambiaes.l., reared from field-collected larvae were used for assessing resistance intensity to permethrin and deltamethrin. They were tested at 1×, 5×, and 10× the diagnostic dose, using both WHO susceptibility tube testing and CDC bottle bioassays. Identification of molecular species, as well as of L1014F Kdrand Ace-1Rmutations was performed using the PCR. The level of expression of biochemical enzymes was also evaluated. Overall, moderate to high resistance intensity to permethrin and deltamethrin was observed, irrespective of the testing method. While the L1014F Kdrfrequency was high (>75%), Ace-1Rwas low (≤6%) in An. gambiaes.s. and Anopheles coluzzii, the two predominant species [52% (95% CI: 44.8–59.1) and 45% (95% CI: 38.0–52.2), respectively]. Anopheles arabiensiswas found at very low frequency (3%, 95%CI: 1.1–6.4). For Biochemical analyses, α and β-esterases were over-expressed in all four districts, while mixed-function oxidases (MFOs) were over-expressed in only one. Overall, the two testing methods led to comparable conclusions, though there were a few inconsistencies between them. The moderate-high resistance intensity observed in the study area suggests that dual active-ingredient (AI) long-lasting insecticidal nets (LLINs) may provide better control of insecticide-resistant mosquitoes.

The study objective was to assess the frequency of the kdr-L995Fand ace-1 G280Sgenetic mutations in Anopheles gambiaes.l. mosquitoes and examine their ability to transmit Plasmodium falciparumin areas where indoor residual spraying (IRS) was implemented with Clothianidin 50 WG. The study was conducted in six communes in the Alibori and Donga departments of which four were IRS-treated and two were untreated and served as control. Post-IRS monthly samples of adult mosquitoes were collected in study communes using human landing catches (HLC). An. gambiaes.l. specimens were processed to detect kdr-L995Fand ace-1 G280Smutations via PCR as well as Plasmodium falciparuminfectivity through CSP ELISA. Our data revealed a high and similar allelic frequency for the kdr-L995Fmutation in both treated and control communes (79% vs. 77%, p= 0.14) whilst allelic frequency of the ace-1 G280Smutation was lower across the study area (2–3%, p= 0.58). The sporozoite rate was 2.6% and 2.4% respectively in treated and untreated communes (p= 0.751). No association was found between Plasmodium falciparuminfection in Anopheles gambiaes.l. vectors and carriage of kdr-L995Fand ace-1 G280Smutations regardless of genotypes. The study findings underline the need for an integrated approach to malaria control, combining different control methods to effectively target transmission. Regular monitoring of insecticide resistance and genetic mutations is essential to guide control strategies.