Mosquito control is a central means by which mosquito-borne diseases such malaria, viral hemorrhagic fever, and lymphatic filariasis can be prevented. Chemical insecticides have traditionally been used for mosquito control, but these agents have negative impacts on other organisms and the environment. These concerns have prompted the development of alternative approaches such as biological control. One of the most widespread and environmentally friendly biological agent is a Cry toxin produced by soil bacterium Bacillus thuringiensis. We improve mosquitocidal Cry toxins more effective using biotechnology. The project will contribute to the control of mosquito as well as mosquito-borne diseases. The use of mosquitocidal Cry toxins, which is an environmentally friendly agent, will contribute the protection of environment by reducing usage of chemical insecticides. The efficient screening device will facilitate use of biological resources.