PROJECT 2 SUMMARY Malaria epidemiology in the Greater Mekong Subregion is characterized by high spatial and temporal heterogeneity with the presence of diverse vector species, which have different spatial distribution, seasonal dynamics, ecological niche requirement, host feeding preference and vector competence. Vector control is an integrated component of malaria control. The changes in mosquito biting behavior and emergence of resistance to pyrethroid insecticides make the conventional pyrethroid insecticide-treated nets and pyrethroid- based indoor residual spray less effective in reducing malaria transmission. Environmental changes, especially due to deforestation, also have led to dramatic changes in the bionomics and vectorial status of different Anopheles species. Therefore, updated knowledge on such changes and development of new resistance monitoring tools are critically needed. In order to address these pressing challenges in vector control, we selected international border regions in China, Thailand and Myanmar to 1) determine how environmental changes affect the mosquito community structures, 2) study the mosquito phenotypic plasticity and characterize landscape genetics of a major Anopheles vector species, 3) identify whether changes of mosquito biting behaviors are genetically determined using genomics technology, and 4) determine the extent, distribution and mechanisms of insecticide resistance in a major malaria vector. The overarching objectives of this project are to understand the vectorial system in diverse ecological and epidemiological settings and to develop the needed knowledge base for effective vector control in the GMS.