Targeted elimination of species‐rich larval habitats can rapidly collapse arbovirus vector mosquito populations at hotel compounds in Zanzibar

Abstract

Understanding the dynamics of larval habitat utilization by mosquito communities is crucial for the design of efficient environmental control strategies. The authors investigated the structure of mosquito communities found at hotel compounds in Zanzibar, networks of mosquito interactions with larval habitats and robustness of mosquito communities to elimination of larval habitats. A total of 23 698 mosquitoes comprising 26 species in six genera were found. Aedes aegypti (n = 16 207), Aedes bromeliae/Aedes lillie (n = 1340), Culex quinquefasciatus (n = 1300) and Eretmapodites quinquevitattus (n = 659) were the most dominant species. Ecological network analyses revealed the presence of dominant, larval habitat generalist species (e.g., A. aegypti), exploiting virtually all types of water holding containers and few larval habitat specialist species (e.g., Aedes natalensis, Orthopodomyia spp). Simulations of mosquito community robustness to systematic elimination of larval habitats indicate that mosquito populations are highly sensitive to elimination of larval habitats sustaining higher mosquito species diversity. This study provides insights on potential foci of future mosquito-borne arboviral disease outbreaks in Zanzibar and underscores the need for detailed knowledge on the ecological function of larval habitats for effective mosquito control by larval sources management.

Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar

“…1 ). The hotels, previously described in Kampango et al [ 23 ], were selected according to compound size (total residential and non-residential area not less than one hectare), accessibility by local means of transportation during low and high tourism seasons, willingness to share data and willingness to accept publication of findings. Consent was obtained from hotel management to conduct the study on their properties.…”

“…Aedes mosquito immature stages were sampled for a period of 10 months from September 2018 to October 2019, encompassing both the rainy and dry seasons. At each hotel, mosquitoes were surveyed over 4 to 6 days in each month using protocols proposed by Tun-Lin et al [ 37 ] and Manrique-Saide et al [ 38 ], with small adaptions as previously detailed in Kampango et al [ 23 ]. For relatively small containers [water volume less than 1 l up to 5 l, e.g., plastic bottles and beer or soda cans (metal containers)], all larvae and pupae were sampled using pipettes.…”

“…aegypti and Ae. bromeliae across urban and rural areas of Zanzibar Island (also known as Unguja) has also been recently confirmed [ 23 – 25 ]. Infestation of Zanzibar Archipelago by these vectors is a serious threat, as arboviral epidemics will have devastating impacts on the fragile public health system and the tourism-based economy.…”

“…However, the tourism industry is also the most important generator of poorly managed non-biodegradable solid waste in Zanzibar [ 27 ]. Some of these solid wastes can sustain a higher diversity of epidemiologically relevant mosquito taxa [ 23 ]. In addition, hotels may concentrate visitors and staff moving to and from different highly endemic regions, which increases the likelihood of contact between local vectors and infectious hosts carrying new variants of mosquito-borne arboviruses.…”

“…This approach, apart from causing widely known environmental repercussions [ 34 ], exerts selective pressure on local vector species to develop resistance to common classes of insecticides, as recently confirmed for Ae. aegypti populations found at different hotels in Zanzibar (Kampango et al [ 23 ], unpublished). This indicates that non-chemical and environmentally sustainable control practices targeting mosquito sources should be implemented to reduce the risk of arbovirus infection exposure.…”