Growth performance and fatty acid composition of mealworm (Tenebrio molitor L.) fed Washingtonia Filifera (Lindl.) H.Wendl. fruit powder

Abstract

ABSTRACT The use of agricultural byproducts as alternative feed ingredients is increasing due to their low cost and sustainability. Fruits of Washingtonia filifera (OPF) represent an underutilized resource with potential to partially replace wheat bran (WB) in Tenebrio molitor diets. This study assessed the effects of different OPF-WB ratios on larval survival, growth, and development. Larvae were reared for six weeks on diets containing 0-100% OPF. Survival and body weight were measured at weeks two, four, and six. Pupal and adult weights were also recorded. The chemical composition of n-hexane extracts was analyzed using GC-MS. Survival remained high during the first two weeks (96.4-98.8%). By week four, survival significantly decreased in the OPF-only group (81.25 ± 2.43%) compared with mixed diets and the WB control (95.50-97.50%). After six weeks, OPF-only larvae had the lowest survival (73.00 ± 1.73%), while mixed diets maintained 89.00-96.50%. Larval, pupal, and adult weights were also reduced under the OPF-only diet, whereas diets containing 25-75% OPF supported growth similar to WB. GC-MS revealed comparable fatty acid profiles dominated by linoleic and palmitic acids. Overall, moderate OPF inclusion can support sustainable T. molitor production.