PAN AFRICAN JOURNAL OF LIFE SCIENCES
e-ISSN: 2672-5924
Volume 10, No. 1, April 2026
Pages 646-653
DOI: 10.36108/pajols/6202/01.0120
Optimizing Black Soldier Fly (Hermetia illucens) Larval Growth on Spent Grain and Cow Dung
Ahmed Dan-Kishiya, Angela Oboh, David Latseumso*
Department of Biological Sciences, University of Abuja, FCT, Nigeria.
Abstract
Background: Growing global demand for sustainable animal protein has intensified interest in alternative feed resources. Black soldier fly (Hermetia illucens) larvae are increasingly recognized for their ability to convert organic wastes into nutrient-rich biomass suitable for animal feed. However, larval productivity is strongly influenced by substrate type and feeding strategy. This study investigated the growth performance, biomass yield, and population stability of H. illucens larvae reared on spent grain (SG) and cow dung (CD) under a progressively increasing feeding regime.
Methods: The study was conducted at the Biological Garden of the Department of Biological Sciences, University of Abuja, Nigeria. A completely randomized design was adopted using two substrates (SG and CD) with two replicates per treatment. Each rearing container was stocked with approximately 600 first-instar lar-vae. Feed quantity increased progressively from 1 kg on Day 1 to 5 kg on Day 12 to match larval nutritional demand. Larval biomass and population counts were measured on Days 1, 3, 6, 9, and 12. Data were expressed as mean ± standard deviation and analyzed using Student’s T-test at P < 0.05.
Results: Larval biomass increased steadily with time in both substrates, but remained consistently high-er in SG. By Day 3, mean biomass reached 53.44 ± 2.71 g in SG and 43.62 ± 8.66 g in CD. Growth continued by Day 6, with biomass values of 102.52 ± 17.02 g for SG and 75.47 ± 21.21 g for CD. A moderate increase was observed by Day 9 (116.64 ± 23.56 g in SG; 87.87 ± 33.73 g in CD). The most substantial biomass gain occurred between Days 9 and 12, when larvae reared on SG reached 1907.07 ± 242.45 g, significantly exceed-ing the 425.61 ± 11.12 g recorded for CD (P = 0.012). Maximum daily growth rates during this final phase were 596.81 g/day in SG and 112.58 g/day in CD. In contrast, larval population counts remained relatively stable throughout the experiment with no significant differences between substrates (P > 0.05).
Conclusion: The findings demonstrate that spent grain supports substantially greater biomass production than cow dung under progressive feeding conditions, highlighting its potential as an efficient substrate for large-scale H. illucens larval production and organic waste valorization.
Keywords: Black soldier fly larvae, Hermetia illucens, spent grain, Larval biomass, Organic waste bio-conversion