Liquid chitosan with essential oils to protect fresh foodstuffs from the oviposition of dipteran pests

One of the FEDKITO project goals is the protection of fresh foodstuffs from the threat posed by target insect pests during post-harvest and post-production stages to try to reduce losses and wastes. Work package 3 focused on the evaluation and comparison of the protection given by liquid chitosan (CH) formulations enriched with specific essential oils (EOs) against the oviposition of four Diptera species: Calliphora vomitoria (Calliphoridae), Piophila casei (Piophilidae), Drosophila suzukii (Drosophilidae), and Ceratitis capitata (Tephritidae). Our deterrence tests were carried out on representative food matrices such as, respectively, raw beef meat, cheese and ham in curing, blueberries, and kumquat fruits. The EOs involved were, first, selected by trained sensory analysts and, then, characterised through Gas-Chromatography coupled with Mass-Spectrometry. We used Laurus nobilis and Piper nigrum EOs to match with meat products and cheese and Cinnamomum verum and Citrus reticulata EOs on fruit. The necessity to enhance and prolong the efficacy of EOs, limited by their volatile nature that causes rapid changes in their composition, was achieved by adding them to CH as a carrier matrix. All the proposed treatments produced a significant oviposition reduction compared to the untreated control samples, and we ascertained prolonged protection over time (up to 72-96 hours) when using the EOs-enriched CH solutions. The results of the trials will be discussed based on the different biology and oviposition behaviour of the four dipteran pests and the suggested practical applications of the liquid CH formulations enriched with EOs in food protection.