Rearing substrate influence on growth performance and nutritional composition of Rhynchophorus phoenicis Larvae (Coleoptera: Curculionidae)

The palm weevil, Rhynchophorus phoenicis, is recognized as a valuable resource for both human and animal nutrition. Despite its potential, limited research has investigated how the choice of rearing substrate affects its nutritional profile and growth performance. This study sought to assess the influence of three locally available substrates on the growth metrics and nutritional attributes of R. phoenicis larvae. Conducted over three months at the Science and Technology Laboratory of Alassane Ouattara University, larvae were raised under controlled conditions in plastic containers with one of three substrates : palm stipe (T1), sugarcane stalk (T2), and maize cobs (T3). Key zootechnical indicators and nutritional parameters were measured. Larvae reared on sugarcane stalks displayed the highest protein content (32.1% dry matter), superior digestibility (82.7%), and a beneficial mineral composition (calcium : 1.8% DM ; iron: 380 mg/kg DM). Those fed on palm stipes showed elevated lipid levels (45.7%) alongside a high survival rate (88.4%). The maize cob substrate provided a well-balanced trade-off between nutritional quality and feed efficiency, evidenced by an optimal feed conversion ratio of 2.5. These findings confirm that the rearing substrate significantly affects both the nutritional quality and growth performance of R. phoenicis larvae. Optimizing feeding strategies could thus pave the way for sustainable and cost-effective insect farming systems in Côte d’Ivoire.