Diatomaceous Earth, A Natural Insecticide for Stored Grain Protection: Recent Progress and Perspectives
Major issues associated with the currently used chemical-based insecticides are insect resistance and toxic residues causing health and environmental risks, with the need for the development of more advanced and environmentally friendly solutions for pest control. In particular, the grain industry needs to reduce its reliance on synthetic pesticides used for stored grain protection because of insecticide deregulation, resistant populations and consumer concern over insecticide residues in food and the environment. One of the promising solutions to address this problem is the use of diatomaceous earth (DE), particles from naturally occurring silica minerals formed by fossilization of green algae (diatoms), which has been successfully proved for many years to have very strong insecticidal effects and could provide chemical-free, resistance-free and environmentally friendly pest control. The unique insecticidal properties of DE particles are based on physical adsorption and abrasion of epicuticular lipids and fatty acids, leading to desiccation of insects and their death. In this chapter, we present recent developments in this field, describing the basic structural and physicochemical properties of DE silica particles, and the influence of their origin, particle size, chemical composition and dosage, as well as the physical conditions (temperature and humidity) and insect species, on their insecticidal performance, including their limitations. Finally, we present the current stage of development of new enhanced DE formulations and their future prospects.