One Hundred Years of Pyrethroid Chemistry: A Still-Open Research Effort to Combine Efficacy, Cost-Effectiveness and Environmental Sustainability

A century after the first scientific research on the chemical structures of pyrethrins was published (in 1923), this paper aims to provide an exhaustive review of the historical research pathways and relative turning points that led to the discovery and mass production of pyrethroids, which have become among the most commercially successful insecticides. These compounds, which are not specific to any particular pest, are used globally and offer cost-effective advantages against a broad spectrum of pests in both agricultural and non-agricultural situations. They are utilized in the context of both harvest and post-harvest applications, as well as in the implementation of public health programs and veterinary applications. Currently, the research for new pyrethroids has essentially reached a standstill due to the increasingly widespread occurrence of insecticide resistance in pests. Nevertheless, several research paths remain open regarding these pesticides. This paper represents the current state of knowledge regarding pyrethroids, exposing both their advantages and disadvantages. Moreover, further investigation, at the molecular level, on their mode of action (MoA) could be very useful to improve their specificity. The results of this review may stimulate additional research for the development of novel pyrethroids having enhanced efficacy, low cost and reduced environmental impact.