Insecticides

Abstract

Abstract Insecticides include a variety of compounds that act against different target species targeting different receptors, enzymes or functions. Hence, there are many chemical groups that also present different species specificity and toxicity for humans. They are used in agriculture, in public health to fight against vectors of disease or nuisance insects, and in veterinary medicine. Some, for example, avermectins, are also used in human medicine. In general, they act on different molecular targets within the nervous system with variable species specificity. For instance, carbamates inhibit acetylcholinesterase (AChE) without significant differences in potency between insects and mammals, while there is a significantly higher sensitivity to neonicotinoids of insects' nicotinic receptors as compared to mammalian ones. Also, significant differences in metabolism are responsible of the low toxicity of pyrethroids to mammalians as compared to insects. Application of insecticides is usually upwards; hence, human exposure during their application may be higher than that following the application of herbicides. Factors that impact on the level of exposure include the amount of active ingredient per hectare, water volume (dilution), the protective equipment used. Dermal exposure is considered to be the most relevant, inhalation accounting for about 10% of total exposure. The Insecticide Resistance Action Committee (IRAC) lists mode of actions and related compounds ( www.irac‐online.org ). It will not be possible to deal with all compounds in this chapter. Therefore, groups with significant current uses will be dealt with. In addition, organophosphates are considered in a separate chapter.