Indoor vs. outdoor habitat of Aedes aegypti and Aedes albopictus: A meta-analysis

Background The invasive mosquitoes Aedes aegypti and Aedes albopictus , known vectors of the agents of dengue, Zika, yellow fever, and chikungunya viruses, threaten millions globally. Therefore, understanding their bio-ecological, behavioral, and bionomic characteristics, specifically larval habitat and adult resting sites, are crucial for implementing effective vector control strategies. This study examines factors associated with Aedes mosquito abundance. Methods A systematic review conducted by following the PRISMA 2020 guidelines, for studies published from January 1998 to December 2024 using PubMed, Embass, Scopus, and Web of Science. We implemented a random-effects model to estimate the relative abundance of adult female Ae. aegypti and Ae. albopictus in the indoor and outdoor environment, adjusted for variability across these studies. The relationship between predictor variables and the mosquito relative abundance was evaluated using meta-regression models. Results A total of 9,720 publications were identified, with 38 publications meeting the inclusion criteria, which represented work done in 18 countries of three continents (Asia, Africa, and the Americas). Extracting Ae. aegypti and Ae. albopictus data combined from these studies revealed that 15% were collected indoors and 85% outdoors. Across studies sampling both indoors and outdoors, 49.43% (95% CI: 37.34–61.57%) of the Ae. Aedes aegypti were sampled indoors and 56.54% (95% CI: 43.79–68.87%) outdoors, while 39.78% (95% CI : 18.81–62.94%) of Ae. albopictus were sampled indoors and 62.02% (95% CIs:47.86–75.21%) outdoors. A subgroup analysis highlighted the highest abundance of both Ae. aegypti and Ae. albopictus in urban areas compared to rural larval sites across all sampling methods. Notably, the sampling of immature Ae. aegypti and Ae. albopictus peaked during both dry and wet seasons, both indoor and outdoor settings, while adult abundance varied by seasons and sampling methods, and exhibited significant associations (P < 0.05) in both indoor and outdoor settings. Conclusion Our findings demonstrate that studies that sample mosquitoes both indoors and outdoors collect more Ae. aegypti and Ae. albopictus in outdoor settings. However, Ae. aegypti shows a stronger tendency to inhabit indoor environments than Ae. albopictus . The results of this systematic review provide knowledge on the basic biology of these two Aedes spp. vectors and provide guidance for designing and implementing arbovirus surveillance in mosquito populations.