Visual cues enhance mating success in laboratory colonies of the malaria vector Anopheles funestus with strain-specific responses

Background Establishing and maintaining laboratory colonies of the malaria vector, Anopheles funestus colonies, using wild-collected material, has proven challenging, in part because of their low propensity to mate in captivity. This study assessed how cage conditions influence the mating success of two Anopheles funestus strains, originally sourced from different geographic areas, Angola (FANG) and Mozambique (FUMOZ). Methods The visual environment in adult mosquito-rearing cages was manipulated either by covering the cages with black cloth to create artificial horizons or by placing contrasting black swarming markers at various positions inside the cages. Mating success was assessed by dissecting the spermathecal capsules of the females after they were reared for 10 days in the cages. Results Overall, mating success was higher in the FANG compared to FUMOZ females, both under artificial horizons (OR = 2.2, 95% CI: [1.83, 2.64]) and visual swarming markers (OR = 3.37, 95% CI: [2.53, 4.49]). Covering the mosquito cages with black opaque cloth and placing a contrasting marker inside the cage increased mating success for both FANG (χ ²  = 27.6, p < 0.001), and FUMOZ (χ ²  = 27.6, p < 0.001) compared to the standard uncovered cage. However, the two An. funestus strains responded differently to the same adult holding conditions. In the FUMOZ strain, mating success increased when the top half of the cage was covered with black cloth (OR = 1.70, 95% CI: 1.18–2.46) or when a contrasting marker was placed at the cage base (OR = 1.98, 95% CI: 1.38–2.85). In contrast, the FANG strain showed improved mating success when the cage side was covered (OR = 2.06, 95% CI: 1.40–3.02). Conclusion This study demonstrates that manipulating the visual environment within adult mosquito-rearing cages can significantly enhance mating success in An. funestus , though the effectiveness of specific visual cues varies between strains. While both FANG and FUMOZ responded positively to visual enhancements, their differing responses to the same conditions underscore the importance of tailoring rearing protocols to the geographic origin of the strain. These findings offer practical guidance for improving the colonization and maintenance of An. funestus in laboratory settings, which is critical for advancing research on this major malaria vector.