Vector Control

Optical information, temperature gradients, trace gases and volatile odors are key sensory inputs for mosquitoes. To mitigate the transmission of malaria, Szabolcs Marka of Columbia University in the U.S. will research how optical irradiation might be used to physically disrupt mosquitoes' sensory systems such that they can't find human hosts. This project’s Phase I research demonstrated that insects are repelled or change their flight behavior in response to different infrared light gradients.

Efforts to control the spread of malaria face serious challenges, including the parasite’s increased resistance to both medications and insecticides and environmental concerns about the use of traditional insecticides. Mosquitoes that spread malaria parasites use their sense of smell to find human hosts, most often by cueing in on the scent of human sweat and the carbon dioxide present in breath. Drs.

Scientists have long known that only relatively old mosquitoes can transmit the agents that cause certain diseases, including dengue fever and malaria. Dr. O'Neill and his multinational team are working on a plan to shorten the lifespan of mosquitoes that transmit the dengue virus, which infects up to 100 million people each year. They are introducing into populations of Aedes mosquitoes, strains of a naturally occurring bacterial symbiont, Wolbachia, that kill infected insects before they are old enough to transmit disease.

The inability to ensure that newly introduced genes will become established within regional mosquito populations has been a major roadblock to the advancement of genetic strategies for vector control. Dr. Burt and his colleagues are investigating homing endonuclease genes (HEGs), so-called "parasitic" genes that can spread rapidly through mosquito populations even if they harm the host insect. This gives HEGs the potential to move newly introduced traits, such as sterility or inability to transmit disease, through a population quickly.

Existing malaria vector control methods (e.g. nets and insecticide sprays) primarily target mosquitoes that enter or attempt to enter human dwellings, yet mosquitoes also obtain significant proportions of essential resources outdoors. Fredros Okumu of Ifakara Health Institute in Tanzania and his co-investigators therefore proposed the use of strategically-located outdoor vector control devices. In this project's Phase I research, the team created new and easy-to-use outdoor methods for luring, trapping and killing mosquitoes, including major African malaria vectors.

Luna Kamau of the Kenya Medical Research Institute in Kenya will investigate how feeding on selected compounds affects male Anopheles mosquito fertility and subsequently, mating competiveness. The compounds could be presented in sugar meals or introduced into larval breeding sites to control mosquito population densities, thereby reducing malaria transmission.

Lawrence Braack of the University of Pretoria in South Africa seeks to demonstrate that malarial mosquitoes in Africa have a strong preference for biting on ankles and feet, and by protecting the lower legs and feet of people who are active outdoors in the early evening with repellants and insecticides, a major reduction in transmission of malaria could be achieved.

Miguel Soares of Instituto Gulbenkian de Ciencia in Portugal will test the theory that antibodies directed against a specific carbohydrate produced by gut pathogens play a role in immunity against severe forms of malaria. Newborns and young children, who are most susceptible to these severe forms of the disease, have not yet built up antibodies to this carbohydrate. Soares will assess whether stimulating production of this antibody in young children can offer them increased protection.

Bart Knols of K&S Consulting in the Netherlands will develop and test a surface coating that slowly releases mosquito attractants and a pesticide that female mosquitoes take back to breeding sites to kill emerging larvae. If successful, the coating can be used as a household paint to induce birth control in vector populations, thus reducing transmission.

Rosemarie Hartman and Seth Rose of Arizona State University in the U.S. will develop and test novel skin-binding insect repellents that slowly release the repellent over a period of weeks. The reduced need for repeated application could increase usage to provide sustained protection against mosquitoes that transmit malaria.