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Abstract ” For more than 90 years, the house-flies have been regarded as a potential and important vector for transmission of several enteric infections such as dysenteries, infantile diarrhoea, typhoid, food poisoning, cholera and parasitic worms (helminthes). They have been also incriminated as vectors of poliomyelitis and certain skin diseases such as yaws; hence the house flies constitute one of the greatest problems of human public health. Also, mosquitoes create a health menace for human, animals and birds. Some of the most deadly diseases of man, such as malaria, encephalitides, yellow fever, dengue fever and filariasis are mosquito borne. Recently, it had been reported that mosquitoes can transmit hepatitis B virus (El-Alarny et al .,1979) and AIDS (Siemens, 1987). Therefore, the control of these vectors, by chemical insecticides had been used as a method to combat these diseases in various parts of the world. Today, the commonly used insecticides are neurotoxicants and act by poisoning the nervous systems of the target organisms (Busvine, 1980). The central nervous system (eNS) of insects is highly developed and not unlike that of the mammals. Although the peripheral nervous system (PNS) of insects is not as complex as that of the mammals, yet there are striking similarities (Amdur et al., 1991). As a fact, insecticides are not selective and affect nontarget species as readily as target organisms, therefore it is not surprising that a chemical that acts on the insect nervous system will elicit similar effects in higher forms of life (Gruzdyev et al., 1983). |