New Mosquito Control Techniques as Countermeasures Against Insecticide Resistance

Chemical substances, whether naturally occurring or artificially synthesized, continue to play an extremely beneficial role in human life. Life would be unsustainable without the benefits by products of chemical reactions, such as oxygen, water, and various types of nutrient substances. Drugs, foods, fibers, pesticides, etc. have been artificially designed and produced for protecting and improving the quality of human life. Nonetheless, chemical substances have been implicated in the deterioration of human environments and ecosystems. One of the main reasons for this unfair accusation might be inadequate regulations and information due to lack of scientific knowledge based on well founded ecotoxicological and pharmacological researches. Lack of information regarding chemicals has been the major factor that has led to undue credence being given to naturally occurring substances, and social movements, which are propagated by a handful of “fanatics,” for resisting artificial chemicals. Biorational and logical approaches by both users and suppliers of chemical substances are therefore required so that humans may continue to benefit from the correct use of chemicals. Developmental research on pesticides of natural origin is believed to be one of the biorational approaches since it may reduce the adverse environmental impact of chemicals to the level of naturally occurring substances. One of the most successful events in the development of pesticide chemicals was the discovery of pyrethrum and the successful synthesis of pyrethroids. For example, one of the most classical synthesized pyrethroids allethrin (Schechter et al., 1948) continues to be used for preventing mosquito bites without any toxicological and operational problems. The use of pyrethroids for preventing mosquito bites is believed to be biorational because this chemical is safe for mammals. The most popular and long-standing formulations using pyrethroids are mosquito coils, mosquito mats, and liquid vaporizers. Pyrethroids belonging to the knockdown agent group, such as allethrin, pyrethrin, and prallethrin, are used in these formulations. In particular, d-allethrin still continues to be used in these types of formulations. Recently, a group of newly developed pyrethroids with high vapor pressure has come to open new era for pyrethroids. Metofluthrin is one of the above promising pyrethroids having high insecticidal activity and high vapor pressure (Ujihara et al., 2004). Metofluthrin belongs to the group of knockdown agents but has a unique