Tactics of Insect Control, Particularly in Medical Entomology

Abstract

AbstractChlorinated hydrocarbon insecticides and notably DDT have provided means of effectively controlling mosquitoes, blackflies and insects of medical importance not only in Canada but elsewhere, and of eradicating the transmission of malaria by anophelines, the world programme for which is already successfully half completed. However resistance has developed to these insecticides in 80 species of public-health importance, including 3 in Canada. Basic studies on the physiological mechanism and mode of inheritance of resistance in Culicine mosquitoes are being performed in Canada. Among insects and mites of agricultural importance, 14 species have developed resistance in Canada, and a world total of 77. Basic studies on the mode of inheritance of cyclodiene-resistance in root maggots are being undertaken in Canada. Countermeasures against resistance include the use of synergists, non-detoxicatable analogues, and negatively-correlated compounds. Resistance usually dictates a shift from the chlorinated-hydrocarbon to the organophosphorus insectices, thus reducing the residue problem, particularly for wildlife. Alternative methods of control include the sterile-male technique, with 2 successful examples but no success yet with mosquitoes, and the use of chemosterilants, with an example of imminent success against houseflies on islands. Chemosterilants however, like bacterial toxins, are not free from the possible development of resistance by detoxication.