Production practices and trait preferences of black soldier fly in selected agro-ecological zones of Uganda

Abstract

Black soldier fly (BSF) larvae production is one of Uganda's fastest-growing insect value chains, with the potential to lift 4.53 million people over the poverty line and provide annual employment to up to 563,302 people. This study aimed to enhance the BSF value chain by characterizing black soldier fly production practices, identifying the preferred traits of black soldier fly larvae, and examining the factors influencing the productivity of these larvae in selected Agro-Ecological Zones (AEZs) of Uganda. The findings are intended to inform the design and implementation of a breeding program focused on improving the production of black soldier fly larvae. A cross-sectional study was conducted in which BSF farmer-households (n=83) from three agro-ecological zones (AEZs), including North-Eastern Savannah Grasslands (ESG), Lake Victoria Crescent (LVC), and Western Savannah Grassland (WSG), were interviewed using a questionnaire with semi-structured and structured questions. The main production objectives and traits preferred for potential genetic improvement were identified using ranking approaches with a Likert scale ranging from 1 (not important) to 5 (most important). Descriptive statistics were used to analyze data on socio-demographic information, production practices, morphometric traits sampled, and production challenges. The chi-square test examined the association between demographics and other characteristics of farmers with the production objectives, practices, and preferred BSF traits. Lastly, a linear regression model was used to determine factors affecting the yield of black soldier fly larvae produced. Results indicate that the main production objective for BSF farming was to feed farmers' own livestock, mostly poultry. Males dominated BSF farming (67.5%), with slightly over half of the respondents aged between 18 and 35, and most (75.2%) having attained tertiary-level education and having received technical training in BSF farming (80.7%). The production scale of BSF farming was generally still low, with the majority (54.2%) producing less than 100kg/week of fresh larvae, mainly under the vertical rearing system (68.7%). BSF breeding stock was mainly obtained from fellow producers (59.04%) who offered training. Market waste was the highest-yielding substrate reported (38.5%), yet it was less (20.5%) preferred and used than brewery waste (26.5%). Most farmers purchased substrates off-farm (56.6%), and only 25.3% used on-farm waste generated. Sieving (50.06%) and manual picking (36.14%) were the two common BSFL larvae harvesting methods practiced, while separation (83.33%) of the pre-pupa from larvae prior to pupation was the main post-harvest handling practice carried out, whilst a few washes of BSFL (16.67%) prior to feeding and selling. The most important trait preferred and significant in all AEZs was high protein content larvae (20.3%), although ranked third (Median rank= 5, p < 0.043). Other important traits were big larvae girth (18.8%), which ranked highest (Median rank = 5), followed by long larvae length (15.3%), which ranked second (Median rank 5). Substrate sourcing was the main production challenge observed in all AEZs and positively influenced the BSFL yield. Overall, most farmers participating in black soldier fly farming are still producing at a small scale due to an inadequate supply of substrates, and they mainly obtain substrate from off-farm sources to enhance their production. Farmers who farm black soldier flies are well-educated and trained in BSF farming, with experience ranging from 1 to 2 years. They mainly produce BSFL under vertical rearing systems and non-permanent structures. Farmers are mainly interested in producing big girth larvae with high protein content and adaptability to high-temperature farming conditions. However, they are limited by inadequate substrate supply, which significantly influences the yield of larvae they produce (p < 0.012). This study's findings can guide further studies aimed at developing breeding programs, better understanding farmers' production practices under different rearing systems, and guiding the navigation of the production challenges faced by black soldier fly farmers to realize efficient and increased production.