Omega-3 on the fly: long-legged fly Machaerium maritimae as a potential source of eicosapentaenoic acid for aquafeeds

Abstract

The need for more sustainable aquafeeds has prompted the exploration of insects as potential ingredients. However, commonly reared insects are not satisfactory regarding their fatty acid composition, lacking omega-3 long chain polyunsaturated fatty acids (n-3 LC PUFA), important nutrients for marine organisms. In this study, we present in detail the fatty acid profile of the long-legged fly Machaerium maritimae Haliday (Diptera: Dolichopodidae), an amphibiotic insect native to European coastal habitats. Specimens of this fly were collected in Ria de Aveiro coastal lagoon (Portugal) and the fatty acid profile was analysed through gas chromatography coupled with mass spectrometry. Results revealed a remarkably high level of n-3 LC PUFA, (11 μg/mg dry weight, 20% of the fatty acid profile) namely eicosapentaenoic acid, and a low level of saturated fatty acids. This value is higher than what is found in Hermetia illucens (black soldier fly), while comparable to other aquatic insects. We also report the presence of 50 distinct fatty acids, including multiple branched-chain and PUFA, and discuss potential implications of their presence on the ecology of this species. Variation in the fatty acid profile along the landscape is also presented. Our results indicate that M. maritimae can potentially be a high-quality lipid source for marine aquafeeds. Current legislation in Europe allowing the use of insects in aquaculture is restricted to a few selected species, often non-native, however, further research should consider native insects as potential alternatives to current ingredients in aquafeed.