Starch-driven optimisation of manure bioconversion by housefly larvae

Housefly larvae can convert fresh animal manure into valuable insect biomass, but their performance is constrained by the low availability of digestible carbohydrates in manure. This thesis investigated whether starch supplementation can improve larval growth and manure bioconversion. A literature synthesis identified key knowledge gaps, followed by experiments examining the effects of starch supplementation using microbial activity, starch dose, larval age and larval density as determinants. The effects of starch were highly dose-dependent: moderate supplementation substantially increased larval biomass and nitrogen bioconversion. Responses also depended strongly on (initial) microbial activity in the manure, with results indicating competition between larvae and manure microorganisms for digestible carbohydrates. Older larvae utilized starch more effectively than younger larvae, supporting developmental regulation of starch digestion. Increasing larval density improved early survival in starch-supplemented substrates but reduced late-stage growth. Overall, the results show that optimizing digestible energy supply and rearing conditions can substantially improve housefly-based manure bioconversion.