Imidacloprid, a Novel Chloronicotinyl Insecticide: Biological Activity and Agricultural Importance

Abstract

Following the discovery of the insecticidal properties of the heterocyclic nitromethylenes (Soloway et al. 1978), chemists of Nihon Bayer Agrochem started in 1979 to optimize these structures. In 1985 the coupling of the chloropyridyl moiety to the N-nitro substituted imidazolidine ring system enabled the synthesis of the highly active insecticide imidacloprid (Fig. 1). Imidacloprid is the first commercial example of the chloronicotinyl insecticides acting on nicotinic acetylcholine receptors (Leicht 1993). It is now registered in more than 60 countries as a compound with a new or non-conventional mode of action to combat highly resistant insect pests (Elbert et al. 1991; Elbert et al. 1996; Nauen et al. 1996a). Chloronicotinyl insecticides will grow in importance in the coming years because other close analogues of imidacloprid, such as Takeda’s and Nippon Soda’s open chain derivatives nitenpyram and acetamiprid, respectively, have been described (Tomizawa et al. 1995; Yamamoto et al. 1995). During recent years several studies have demonstrated the excellent activity of imidacloprid on pest species of different orders. The present chapter gives an overview of the biological activity of imidacloprid on different target pests, its selectivity even at the molecular level, its physicochemical properties which led to good systemicity and its agricultural importance.