From waste to opportunity: evaluating the pesticidal properties of a waste cooking oil and its derivates

The development of novel eco-friendly formulations to control pests represents a viable strategy for a more sustainable agriculture, according to the Farm to Fork Strategy. The current work aimed to test the potential activity of a waste cooking oil (WCO) from domestic use and its derivates, including a deacidified oil and its methyl ester (obtained according to literature procedures) as well as potassium salts of fatty acids (obtained by alkaline hydrolysis), against some weeds at their juvenile stage in greenhouse and a model insect (Planococcus ficus) in laboratory conditions. Laboratory bioassays were conducted to compare the acute toxicity of bio-based products and standard formulations against different insect development stages as well as to calculate LC50 and LC95 of each product tested. While none of the tested bio-based products caused symptoms of phytotoxicity in weeds, they demonstrated pesticidal activity against insects under laboratory conditions. The tested products caused mortality of P. ficus nymphs and adults. Overall, potassium salts of fatty acids at the dose of 1.2% (v/v) caused 97.5 and 92.5% mortality of 2nd and 3rd instar nymphs and adult females, respectively, thus being comparable to that of standard formulations. A concentration-dependent effect between LC50 and LC95 was observed, varying with product and insect development stage. However, only the formulation of potassium salts of fatty acids was able to provide similar LC50 and LC95 values between nymphs and adult females. Our findings highlight the importance of conducting further research on the development of potential insecticidal products derived from WCOs for a more sustainable agriculture.