The crucial first step in establishing a SFS is identifying an appropriate site that adequately captures the environmental conditions experienced by local mosquito species. Additional logistic criteria include ease of access by research personnel and electricity/water supply, being situated where potential hazards to surrounding residents arising from accidental vector release are negligible, and continual monitoring by security staff is possible. Trade-offs may arise in attempting to maximize all these criteria at particular locations which will require careful case-by-case consideration. For example, it has been suggested that the best way to limit hazards posed by unintentional release of mosquitoes into the environment would be to build containment units as far away from communities as possible [55 ]. However, the majority of SFS currently in existence and being planned are located within disease-endemic settings in the developing world. In many of these settings, access to roads, water, an electrical supply, and reliable 24-hour surveillance is possible only near towns or cities. In balancing these components of potential risk, it was decided to select a site for the SFS that is within the campus of the IHI, which is located in Ifakara town. By building within the fenced-off perimeter of the research centre, it was possible to ensure constant surveillance and containment, and strictly control those who had access to the SFS.
Another key factor in the site selection process for SFS is the availability of background data on the dynamics of local vector populations and their disease transmission ability [55 ]. This information is essential to examine how closely the behaviour, life-history and population dynamics of contained vectors represent those of the wild. As mosquitoes in the SFS will be exposed to many of the same environmental conditions as those of neighbouring populations (e.g temperature, humidity, vegetation), it is anticipated they will be subject to similar selective forces. However, one deviation from complete 'naturalness' was made in the IHI SFS by covering its roof with polyethylene plastic; a decision taken on the basis that this compromise would permit experimental manipulation of rainfall in future experiments. How this modification influences the environmental suitability of the SFS relative to ambient conditions can be assessed by comparison of mosquito population dynamics in the SFS with those of the surrounding area. An advantage of selecting a site in Ifakara was that substantial baseline epidemiological and entomological information on the dynamics of malaria and Anopheles populations in the area is already available [50 (link),54 (link),56 (link),57 ]. Additionally, detailed knowledge of mosquito ecology exists for the Kilombero valley, and new studies specifically addressing the mating biology [29 (link)-31 (link),58 (link)] and population genetics (Ng'habi et al., in prep.) of An. gambiae and An. arabiensis within this region were initiated concurrently with the establishment of the SFS.
Another key factor in the site selection process for SFS is the availability of background data on the dynamics of local vector populations and their disease transmission ability [55 ]. This information is essential to examine how closely the behaviour, life-history and population dynamics of contained vectors represent those of the wild. As mosquitoes in the SFS will be exposed to many of the same environmental conditions as those of neighbouring populations (e.g temperature, humidity, vegetation), it is anticipated they will be subject to similar selective forces. However, one deviation from complete 'naturalness' was made in the IHI SFS by covering its roof with polyethylene plastic; a decision taken on the basis that this compromise would permit experimental manipulation of rainfall in future experiments. How this modification influences the environmental suitability of the SFS relative to ambient conditions can be assessed by comparison of mosquito population dynamics in the SFS with those of the surrounding area. An advantage of selecting a site in Ifakara was that substantial baseline epidemiological and entomological information on the dynamics of malaria and Anopheles populations in the area is already available [50 (link),54 (link),56 (link),57 ]. Additionally, detailed knowledge of mosquito ecology exists for the Kilombero valley, and new studies specifically addressing the mating biology [29 (link)-31 (link),58 (link)] and population genetics (Ng'habi et al., in prep.) of An. gambiae and An. arabiensis within this region were initiated concurrently with the establishment of the SFS.
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