Aphicidal Activity and Phytotoxicity of ICitrus sinensis/I Essential-Oil-Based Nano-Insecticide

Research about innovative sustainable ecofriendly pesticides is a key topic of global interest, aiming to reduce synthetic inputs in agriculture, to protect biodiversity, and to ensure food safety to consumers. Botanical substances, and in particular essential oils, are among the most promising natural pesticides, as can be seen from the incredibly large number of published studies in the last two decades. Nevertheless, most research is limited to laboratory studies, leaving a gap between scientific studies and field applications. In this scenario, the aim of this paper was to evaluate the feasibility of an innovative nano-insecticide containing sweet orange essential oil as the active ingredient against a key aphid pest in real conditions. Due to its high polyphagy, Aphis gossypii is considered a key pest of many crops, and it can feed on hundreds of plant species belonging to the families Cucurbitaceae, Malvaceae, Solanaceae, Rutaceae, and Asteraceae. The control of this pest mainly relies on synthetic insecticides whose adverse effects on the environment and human health are encouraging researchers to explore innovative, alternative solutions. In this scenario, essential oils (EOs) could play a key role in the development of ecofriendly pesticides. In this study, the development of a citrus peel EO-based nano-formulation and its biological activity against A. gossypii both in the laboratory and field were described and evaluated. The phytotoxicity towards citrus plants was also assessed. The developed nano-insecticide highlighted good aphicidal activity both in the laboratory and field trials, even at moderate EO concentrations. However, the highest tested concentrations (4 and 6% of active ingredient) revealed phytotoxic effects on the photosynthetic apparatus; the side effects need to be carefully accounted for to successfully apply this control tool in field conditions.