Investigating the potential of cassava-based substrates supplemented with various agricultural co-products for Rhyncophorus phoenicis (Fabricius, 1801) and Hermetia illucens (Linnaeus, 1758) farming in Cameroon

Abstract

This study is conducted in the context of a global shift towards more sustainable agricultural practices, with a focus on developing alternative food and feed sources based on insect farming. The edible African palm weevil larvae Rhyncophorus phoenicis F. (Coleoptera: Dryopthoridae), traditionally harvested from the wild, presents an opportunity for sustainable farming in many African countries especially Cameroon, but requires efficient, locally adapted farming methods. This thesis conjointly investigates the potential of cassava-based substrates, supplemented with various agricultural co-products, to support the growth of Rhyncophorus phoenicis and black soldier fly Hermetia illucens L. (Diptera: Stratiomyidae). The research tested the growth performance, fat content, and fatty acid profile of larvae reared on substrates containing wheat bran, brewer’s spent grain, and palm kernel meal. Results showed that wheat bran supplementation significantly improved the growth of both insects’ larvae compared to non-supplemented cassava diets, suggesting its potential as a sustainable feedstock. Although black soldier fly larvae could thrive on all tested diets due to their adaptability, the study suggests that, from an economic standpoint, it is more effective to use low-value organic waste for their farming rather than cassava-based feeds.