The Malaria Landscape: Mosquitoes, Transmission, Landscape, Insecticide Resistance, and Integrated Control in Thailand

Abstract

This chapter presents results on the effect of land use on malaria vector density, species diversity, and insecticide resistance in northern Thailand. Entomological data from 1977 to 1999 was analysed to understand spatio-temporal variations in vector density and potential effects on malaria transmission. Landscape analysis can potentially be used as a tool in vector control strategy development, particularly to understand local vector behaviour and habitat characteristics for stratification of vector control areas. Our results show that an increase in landscape diversity, particularly forest fragmentation, reduces malaria vector diversity and density. Such land use changes in non-malaria transmission areas were the potential cause for reductions in malaria mosquito densities. Similar land use changes were not observed in areas with permanent malaria transmission. The landscape analysis further shows that agricultural intensification increases the likelihood of insecticide resistance development in malaria mosquitoes. We therefore argue for intersectoral collaboration, especially between the public health and agricultural sectors, to develop and implement integrated insecticide resistance management plans and integrated control. Integration of pest and vector control strategies should build on the integrated pest and vector management (IPVM) strategies described in this chapter. Such a strategy should be implemented through the Farmer Field School approach. For future research topics we suggest studies on the bionomics of the sibling species of the malaria vectors in the region to more effectively implement vector control actions. Furthermore, the effect of IPVM strategies on vector populations and disease outcome should be evaluated through large-scale trials.