Growth Characteristics and Lipid Content of Black Soldier Fly (Hermetia illucens) Larva Reared in Milkfish Offal and Mixed Vegetable Wastes

Abstract

Black soldier fly larva (Hermetia illucens) of BSFL has long been eyed as a potential waste-to-energy bioconversion tool to convert organic waste into biomass (lipids) which would then be converted into biofuel. The effect of different feeds, namely, chick starter mash (control), milkfish offal, and mixed vegetable waste, on the growth characteristics and nutritional profile of black soldier fly larvae were determined in this study. Daily measurements of length, width, and mass of the larvae were done from hatching to the pre-pupal stage. The gathered mass of the larva as a function of time was fitted through a Gompertz growth equation. The growth experiment with these substrates showed that larvae reared in milkfish offal rendered the highest growth rate and largest terminal mass, length, and width. Furthermore, they also showed significantly higher efficiency of conversion of digested feed and survival rate than the other two substrates (control and vegetable waste). The nutritional profile was determined as fractions of crude protein, crude fat, carbohydrate, and ash. The proximate analysis reported the highest protein and carbohydrate content of the larvae reared in milkfish offal at 38.95% and 44.45%, respectively. Meanwhile, larvae raised in vegetable waste obtained the highest fat and ash content at 40.55% and 15.2%, respectively. The results dictated by the proximate analysis implies a potential for the rearing of black soldier fly in vegetable waste substrates as source of lipids for biodiesel feedstock through a low-cost waste-to-energy system.