Malaria kills between one and two million people a year. International initiatives such as Roll Back Malaria are committed to halving the burden of malaria through the use of anti-malaria drugs and attacking the mosquitoes that spread the disease. Current efforts against mosquitoes are based largely on the use of insecticide-treated bednets and indoor application of insecticides but there is a pressing need for new strategies which will be applicable in different environments, affordable, and complementary to existing interventions.
One possible strategy is to control mosquito populations is to treat their breeding sites (i.e. all aquatic areas) with a larvicide. However, such a non-selective strategy is not only logistically difficult and expensive but raises environmental concerns. NRI is therefore teaming up with scientists from the London School of Hygiene and Tropical Medicine, the Royal Institute of Technology, Sweden and the International Centre for Insect Physiology and Ecology, Kenya to assess whether a more targeted approach can be developed.
Mosquito larvae are not found in all water bodies. Preliminary data suggests that different bodies of water produce different odours, according to the bacteria present, and that pregnant female mosquitoes use these odours to select suitable breeding sites. If we can understand the chemical ecology underlying this process then we will have the basis for identifying key breeding sites and hence a rational basis for selective larviciding.
At NRI, Steve Torr, Gabriella Gibson and David Hall, along with PhD students Frances Hawkes and James Broom, are carrying out laboratory studies to quantify the behavioural responses of mosquitoes to natural odours and identify the particular chemicals which cause these responses.