Vector ecologists increasingly recognize that the ability to make inferences between laboratory experiments of insect biology and epidemiological trends observed in the field is hindered by a conceptual and methodological gap occurring between these approaches which prevents hypothesis-driven empirical research from being conducted on relatively large and environmentally realistic scales.  The development of Semi-Field Systems (SFS) has been proposed as the best mechanism for bridging this gap.  SFS can be defined as enclosed environments, ideally situated within the natural ecosystem of a target disease vector, in which all features necessary for its lifecycle completion are present.  SFS provide several unique advantages in comparison to standard field approaches.  Foremost is the ability to conduct large-scale, repeated manipulative experiments on vector abundance, species composition and habitat use that are simply not possible within natural populations.  Because the number of vectors used in SFS experiments is often under researcher control, precise estimates of the proportion of the population responding to particular environmental cues and interventions can be obtained.  Consequently, SFS can be viewed as an invaluable tool for estimation of life-history, behavioural and fitness traits essential for the parameterization of mathematical models of vector population dynamics, transmission potential and evolutionary response.  An additional practical advantage of these systems is that as insect vectors used in SFS experiments can be maintained infection-free, researchers can conduct high-throughput assays of novel control methods without risking any exposure to disease.  Recently we established what is currently the world’s largest SFS at the Ifakara Health Institute in southern Tanzania, for study of malaria vector ecology.   Here I will summarize current progress in the use of this SFS to address two major issues in vector ecology and control: (1) the use of alternative (livestock) hosts as a strategy to reduce malaria transmission, and (2) the feasibility of encouraging laboratory-reared (genetically-modified) individuals to mate with their wild counterparts in order to spread pathogen resistance genes.

Results/Conclusions

Preliminary observations indicate that realistic and repeatable observations of anopheline behaviour are obtainable within the SFS at Ifakara, and that habitat and climatic features representative of field conditions can be simulated within it.  Several new insights have been gained with respect to the ecological basis of habitat, host and mate choice of Anophelines that would not have otherwise been possible.  The implications of these data for malaria control strategies are discussed, as are the inherent limitations of these systems.