Journal Papers

Bulinda C., Gido E.O., Kirscht H., Tanga C.M., Gendered Awareness of Pig and Poultry Farmers on the Potential of Black Soldier Fly (Hermetia illucens) Farming in Kenya, MDPI Sustainability, Vol. 15, Issue 4, February 2023

Given the need to boost food production while guaranteeing environmental sustainability, the black soldier fly (BSF) (Hermetia illucens (L.), Diptera: Stratiomyidae) is gaining traction worldwide as an alternative protein source. In Kenya, BSF production and its use as a feed component is an emerging business, but farmer awareness of the potential use of BSF in animal feed has received limited attention. This study examined the factors influencing farmer awareness of insect farming and its usefulness as ingredient in livestock feed from a gender perspective. The analysis employed a mixed-methods approach by combining binary logistic regression analysis using cross-sectional survey data from a sub-sample of 235 pig and poultry farmers and content analysis from in-depth phone interviews. The study was implemented in Kiambu County, Kenya. About 44% of the farmers were aware of the use of black soldier fly in the animal feed industry, of which 46.72% were female, and 41.59% were male. From the results, years of education, the number of chickens owned, and membership in agricultural groups significantly influenced male and female farmers’ awareness. In addition, age and the number of pigs owned significantly influenced female farmers’ awareness. The results suggest that these factors are important to consider when strategies are developed to create awareness of BSF farming. Lessons learned from this study will inform BSF dissemination strategies to better target potential men and women BSF producers, influence their decision-making ability and improve information flows between scientists and producers.

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Kariuki E.G., Kibet C., Paredes J.C., Mboowa G., Mwaura O., Njogu J., Masiga D., Bugg T.H., Tanga C.M., Metatranscriptomic analysis of the gut microbiome of black soldier fly larvae reared on lignocellulose-rich fiber diets unveils key lignocellulolytic enzymes, Frontiers in Microbiology, Vol. 14, Issue 26, April 2023

Recently, interest in the black soldier fly larvae (BSFL) gut microbiome has received increased attention primarily due to their role in waste bioconversion. However, there is a lack of information on the positive effect on the activities of the gut microbiomes and enzymes (CAZyme families) acting on lignocellulose. In this study, BSFL were subjected to lignocellulose-rich diets: chicken feed (CF), chicken manure (CM), brewers’ spent grain (BSG), and water hyacinth (WH). The mRNA libraries were prepared, and RNA-Sequencing was conducted using the PCR-cDNA approach through the MinION sequencing platform. Our results demonstrated that BSFL reared on BSG and WH had the highest abundance of Bacteroides and Dysgonomonas. The presence of GH51 and GH43_16 enzyme families in the gut of BSFL with both α-L-arabinofuranosidases and exo-alpha-L-arabinofuranosidase 2 were common in the BSFL reared on the highly lignocellulosic WH and BSG diets. Gene clusters that encode hemicellulolytic arabinofuranosidases in the CAZy family GH51 were also identified. These findings provide novel insight into the shift of gut microbiomes and the potential role of BSFL in the bioconversion of various highly lignocellulosic diets to fermentable sugars for subsequent value-added products (bioethanol). Further research on the role of these enzymes to improve existing technologies and their biotechnological applications is crucial.

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Muinde J., Tanga C.M., Olukuru J., Odhiambo C., Tonnang H.E.Z., Senagi K., Application of Machine Learning Techniques to Discern Optimal Rearing Conditions for Improved Black Soldier Fly Farming, MDPI Insects, Vol. 14, Issue 5, May 2023

In recent years, farming the black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomydiae) has gained popularity across the globe due to its usefulness mainly in animal feed production and waste management. The short cycle time taken to rear the BSF and the high protein content present in its larvae makes it a suitable source of feed for a variety of animals (e.g., poultry, fish, and pigs); the livestock bred as food for humans. However, despite the farming of black soldier fly larvae (BSFL) as a source of feed, its production levels are low and do not meet the existing market demand. This study explored data science and machine learning modeling approaches to discern optimal rearing conditions for improved BSFL farming. The random forest regressor machine learning algorithm gave the best prediction results. The algorithm also ranked the variables that contributed most to the prediction of the expected larvae weight. Given the studied rearing conditions, the prediction algorithm can discern and predict the expected weight of BSFL to be harvested. Tuning the production system parameters according to the order of the ranked parameters can further optimize the production of BSFL. BSFL are a source of feed for the animals that are a source of food for humans; therefore, this research contributes to alleviating food insecurity.

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Munguti J.M., Obiero K.O., Iteba J.O., Kirimi J.G., Kyule D.N., Orina P.S., Githukia C.M., Outa N., Ogello E.O., Mboya J.B., Ouko K.O., Liti D., Yossa R., Tanga C.M., Role of multilateral development organizations, public and private investments in aquaculture subsector in Kenya, Frontiers in Sustainable Food Systems, Vol. 7, August 2023

Rapid population and economic growth, increased health benefits of aquatic food, and changes in lifestyles and preferences as a result of rapid urbanization and globalization are all contributing to the rapid growth of aquaculture production in Kenya. Despite significant investment efforts from the national and devolved governments as well as donors and international organizations, smallholder aquaculture production is yet to result in a significant increase in incomes and improved food and nutrition security. We conducted a scoping review to investigate the roles of multilateral development organizations, international financial institutions, and public and private investments in Kenya’s aquaculture subsector. We draw on lessons learned from previous projects implemented at the national, county, and farm levels to make recommendations for sustainable aquaculture intensification in Kenya. To unlock Kenya’s aquaculture potential and improve its food and nutrition status, deliberate efforts must be made to create a conducive environment for public and private investment in the industry. First, there is a need to coordinate and clearly articulate the roles and responsibilities among devolved and national governments, donors, and financial institutions through public-private partnerships to ensure optimal allocation of financial, human, and infrastructure resources. Second, more collaborative research should be devoted to the design and construction of climate smart culture systems, developing new species to guarantee supply of high-quality products; developing and scaling low-cost and highly nutritious fish feeds based on novel ingredients; and enhancing resilient livelihoods through innovative aquaculture practices and market linkages to create employment opportunities for youth and women. Finally, the national and devolved governments should create an enabling policy environment through tax incentives and regulatory reforms to combat climate change, protect nature and biodiversity, sustain livelihoods, and mainstream food and nutrition initiatives into the design and implementation of future aquaculture projects.

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Tanga C.M., Kababu M., New insights into the emerging edible insect industry in Africa, Oxford Academic Animal Frontiers, Vol. 13, Issue 4, Pages 26–40, August 2023

Consumption of insects is an ancient practice that is common among many cultures with more than 2 billion people in 113 countries across the world practising entomophagy (van Huis, 2013). More than 2,000 species of edible insects have been recorded worldwide out of which 470 species occur in Africa (van Huis, 2013; Kelemu et al., 2015). The rapid growth in human population and increased demand of animal proteins has drawn more interest on the use of insects as food and feed to mitigate food insecurity and malnutrition (Kewuyemi et al., 2020; Babarinde et al., 2021). Edible insects have a rich profile of proteins, carbohydrates, fats, minerals, vitamins, and bioactive compounds that are essential for human health and nutrition (Zhou et al., 2022). Their high nutrient content, availability and low cost of production has increased their use as a substitute protein source in animal feed (van Huis et al., 2013; Tanga et al., 2021).

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Marcasy P. M., Muliro, P.S., Ngoda, P.N., Ghemoh, C.J., Subramanian, S., Xavier, C., Ochieng, B., Ekesi S., Tanga C.M., Unravelling the nutritional and health benefits of wheat bread enriched with meat powder from laying hen fed diet with insect (Hermetia illucens) meal, Heliyon, Vol. 9, Issue 10, October 2023

Wheat bread is among stable foods that are nutritionally imbalanced, thus enrichment is crucial. We evaluated the nutritional impact of high-valued wheat bread enriched with varying levels of meat powder from hen fed diet with insect (Hermetia illucens)-based meal. Crude protein and ash in bread increased with increasing inclusion of meat powder. Limiting amino acids like lysine and threonine in enriched bread products increased by 3.0–4.5 and 1.8–3.1-folds, respectively. Omega 3 fatty acids were significantly enhanced in bread fortified with meat powder. Vitamins (retinol, nicotinic acid, and pantothenic acid) were significantly increased in supplemented bread products. Iron, zinc, and calcium increased by 1.1, 1.2 and 3.0-folds in enriched bread with 30% meat powder. Colour, flavour and overall acceptability of breads prepared with 25 and 30% meat powder were highly ranked. Our findings demonstrate that meat powder (i.e., from hen fed insect-based diets) enrichment would provide added health and nutritional benefits to bread products without having adverse effects on any functional or sensory properties. Thus, this could be a novel strategy and trend for improving bread products, that might generate increasing demand for a healthier consumer-oriented lifestyle.

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Ouma, L.O., Muthomi, J.W., Kimenju, J.W., Beesigamukama D., Subramanian S., Khamis F.M., Tanga C.M., Occurrence and management of two emerging soil-dwelling pests ravaging cabbage and onions in Kenya, Scientific Reports, Vol. 13, Article number 18975, November 2023

Cabbage and Onion production in sub-Saharan Africa face numerous pest constraints that needs to be overcome to feed the rapidly growing population. This study aimed to establish the occurrence, incidence, and severity of soil-dwelling pests of cabbage and onions, and current management practices in five Counties of Kenya. Our findings revealed that most farmers grew hybrid vegetables on a small scale, which were highly dominated by various pest species (Delia platura, Maladera sp., and Agriotes sp. for cabbage and Atherigona orientalis and Urophorus humeralis for onion. The occurrence, incidence and severity of the various pest species on both crops varied considerably. Over 95% of the farmers relied on synthetic insecticides, which were applied weekly or bimonthly with limited success. Our findings demonstrate that invasive and polyphagous A. orientalis and D. platura were the most devastating pests of onion and cabbage without effective control options. Therefore, effective, sustainable, and affordable management strategies are required to control the spread of these pests to other crops in the region.

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Gómez-Brandón M., Beesigamukama D., Probst M., Klammsteiner T., Zhou Y.Y., Zhu Y-G., Tanga C.M., Garden fruit chafer (Pachnoda sinuata L.) accelerates recycling and bioremediation of animal waste, Elsevier Waste Management, Vol. 173, Pages 131-140, January 2024

Bioconversion of livestock wastes using insect larvae represents an emerging and effective strategy for waste management. However, knowledge on the role of the garden fruit chafer (Pachnoda sinuata L.) in waste recycling and influence on the diversity of microbial community in frass fertilizer is limited. Here, we determined whether and to what extent the conversion of cattle dung into insect frass fertilizer by P. sinuata influences the frass’ microbial community and its associated antibiotic resistance genes abundance. Pachnoda sinuata larvae were used to valorise cattle dung into frass fertilizer; samples were collected weekly to determine the composition of bacteria and fungi, and antibiotic resistant genes using molecular tools. Results revealed that bioconversion of cattle dung by P. sinuata larvae significantly increased the richness of beneficial bacteria in the frass fertilizer by 2.5-folds within 28 days, but fungal richness did not vary during the study. Treatment of cattle dung with P. sinuata larvae caused 2 – 3-folds decrease in the genes conferring resistance to commonly used antibiotics such as aminoglycoside, diaminopyrimidine, multidrug, sulfonamide and tetracycline within 14 days. Furthermore, the recycling cattle dung using considerably reduced the abundance of mobile genetic elements known to play critical roles in the horizontal transfer of antibiotic resistance genes between organisms. This study highlights the efficiency of saprohytic insects in recycling animal manure and suppressing manure-borne pathogens in the organic fertilizer products, opening new market opportunities for innovative and safe bio-based products and achieving efficient resource utilization in a circular and green economy.

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Munguti J., Wekesa F., Osuga I., Kariuki M., Yossa R., Mungai D., Kyule D., Abwao J., Opiyo M., Obiero K., Outa N., Ogello E., Iteba J., Kirimi J.G., Maundu A., Liti D., Tanga C.M., Utilization of Black Soldier Fly (Hermetia illucens) Larvae as a Potential Substitute for Fish Meal in the Production of Nile Tilapia (Oreochromis niloticus L.), Sustainable Agriculture Research, Vol. 13, Issue 1, January 2024

Utilization of quality aqua-feed relies heavily on fish meal sources of protein because of its nutritional balance. However, due to its limited supply, high cost, and decline of wild fish populations, aquaculture production has shifted focus to cheaper and more readily available alternatives to guarantee sustainable aquaculture productivity. Black soldier fly (Hermetia illucens) larvae are a promising replacement for fish meal in fish diets due to their relatively high crude protein, lipid and mineral contents, and the bioactive potential with anti-microbial, and other probiotic properties. This study determined the effect of partially replacing fish meal with black soldier fly meal (BSFLM) on the growth performance of Nile tilapia (Oreochromis niloticus). Four isonitrogenous (30% crude protein) diets in which fish meal protein was gradually substituted with BSFLM were prepared as follows: No BSFLM (control)-T0; 25% (BSFLM25)-T25, 50% (BSFLM50)-T50 and 75% (BSFLM75)-T75. The feeds were fed to the Nile tilapia fingerlings (mean weight 25 ±5 g) which were randomly stocked in 12 cages at a stocking density of 30 fish per cage. The experimental fish were manually fed at 3% of the body weight for 28 days, and 4% of the body weight for 154 days twice a day. The study found that 25% and 50% replacement of fish meal protein with BSFLM resulted in the best growth performance of Nile tilapia, as measured by final mean body weight gain (BWG), specific growth rate (SGR), feed conversion ratio (FCR) and condition factor (K). This suggests that BSFLM is a promising alternative to fish meal in aqua-feeds in the production of Nile tilapia.

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Tanga, C. M., Ekesi, S., Dietary and therapeutic benefits of edible insects: A global perspective, Annual Review of Entomology, Vol. 69, Pages 303-331, January 2024

Edible insects are gaining traction worldwide for research and development. This review synthesizes a large and well-established body of research literature on the high nutritional value and variety of pharmacological properties of edible insects. Positive benefits of insect-derived products include immune enhancement; gastrointestinal protection; antitumor, antioxidant, and anti-inflammatory capacities; antibacterial activities; blood lipid and glucose regulation; lowering of blood pressure; and decreased risk of cardiovascular diseases. However, the pharmacological mechanisms of these active components of edible insects in humans have received limited research attention. In addition, we discuss health risks (safety); application prospects; regulations and policies governing their production and consumption with a view to promote innovations, intraglobal trade, and economic development; and suggestions for future directions for further pharmacological functional studies. The aim is to review the current state of knowledge and research trends on edible insects as functional ingredients beneficial to the nutrition and health of humans and animals (livestock, aquatic species, and pets).

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Wamai L.K., Munga L.M., Osuga I.M., Munguti J.M., Subramanian S., Kidoido M.K., Ghemoh J.C., Mwendia C.M., Tanga C.M., Big opportunities for tiny bugs: rush to boost laying hen performance using black soldier fly larvae meal, Oxford Academic, Journal of Economic Entomology, Vol. 117, Issue 1, February 2024

Rising feed cost challenges due to expensive conventional protein sources continue to make headlines in Africa causing drops in profit margins. We assessed the impact of insect (Hermetia illucens Linnaeus larvae meal, HILM) protein as a substitute for soybean meal and sunflower seed cake on layer chicken performance and profitability. Our results showed that apart from the growers, chicks (12.37 g/bird) and layer hens (2.02 g/bird) fed diets with 75% HILM inclusion levels had significantly higher average daily weight gain. The average daily feed intake (ADFI) and feed conversion ratio (FCR) varied significantly when the chicks and layer hens were provided with the HILM-based diets. For the chicks and layer hens, the lowest ADFI and FCR were observed in birds subjected to diets with 75% and 100% HILM compared to the growers fed diets with 50% HILM. Significantly higher egg production was observed for layer hens fed diets containing 75% of HILM throughout the first (87.41%) and second (83.05%) phase production cycles. Layer hens fed HILM-based diets had a 3–10% increase in egg laying percentage. There was higher profit margins when birds were fed diets containing 75% of HILM (~1.83 and 5.98 US$ per bird), which mirrored the return on investment estimated at 63.95% and 33.36% for the pullets (growers) and laying hen, respectively. Our findings demonstrate that diets with 75% HILM provided optimum growth performance, reduced feeding costs, increased weight gain and egg production as well as improved economic returns for commercial on-farm poultry production systems.

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Achuoth M. P., Mudalungu C. M., Ochieng B. O., Mokaya H. O., Kibet S., Maharaj V. J., Subramanian S., Kelemu S., Tanga C. M., Unlocking the potential of substrate quality for the enhanced antibacterial activity of black soldier fly against pathogens, ACS Omega, Vol. 9, Issue 7, February 2024

Globally, antibiotics are facing fierce resistance from multidrug-resistant bacterial strains. There is an urgent need for eco-friendly alternatives. Though insects are important targets for antimicrobial peptides, it has received limited research attention. This study investigated the impact of waste substrates on the production of antibacterial agents in black soldier fly (Hermetia illucens L.) larvae (HIL) and their implications in the suppression of pathogens [Bacillus subtilis (ATCC 6051), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922)]. The 20% acetic acid (AcOH) extract from market waste had the highest antibacterial activity with an inhibition zone of 17.00 mm, followed by potato waste (15.02 mm) against S. aureus. Hexane extract from HIL raised on market waste also showed a significant inhibitory zone (13.06 mm) against B. subtilis. Minimum inhibitory concentration (MIC) values recorded were 25 mg/mL against all test pathogens. The fastest time-kill of 20% AcOH extract was 4 h against B. subtilis, E. coli, andP. aeruginosa. Lauric acid was also identified as the dominant component of the various hexane extracts with concentrations of 602.76 and 318.17 μg/g in HIL reared on potato and market waste, respectively. Energy from the market waste substrate correlated significantly (r = 0.97) with antibacterial activities. This study highlights the key role of substrate quality and extraction methods for enhancing the production of antibacterial agents in HIL, thus providing new insights into the development of potential drugs to overcome the alarming concerns of antimicrobial resistance.

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Anedo E.O., Beesigamukama D., Mochoge B., Korir N.K., Haukeland S., Cheseto X., Subramanian S., Kelemu S., Tanga C.M., Evolving dynamics of insect frass fertilizer for sustainable nematode management and potato production, Frontiers in Plant Science, Vol. 15, February 2024

Potato production faces major challenges from inadequate soil fertility, and nematode infestation, yet synthetic fertilizers and nematicides are costly and harmful to the environment. This study explored the potential of chitin-fortified black soldier fly-composted organic fertilizer (BSFCOF) as a multipurpose organic fertilizer amendment for enhancing potato yield and suppressing potato cyst nematodes (PCN). The BSFCOF was applied at a rate equivalent to 150 kg N ha-1 and fortified with chitin from black soldier fly pupal exuviae at inclusion rates equivalent to 0.5, 1, 2, 3, 4 and 5% chitin. Data were collected on potato growth characteristics, PCN population densities, and soil chemical properties for two growing cycles. Results showed that chitin fortified BSFCOF significantly improved potato growth parameters, chlorophyll concentration, marketable tuber yield and number of marketable tubers. The marketable tuber yield achieved using chitin-fortified BSFCOF was 70 – 362%, and 69 – 238% higher than the values achieved using unfertilized soil during the first and second growing cycles, respectively. Soil amendment with chitin-fortified BSFCOF significantly reduced the number of cysts per 200 g soil-1, number of eggs and J2 per cyst-1, eggs g-1 soil and reproduction rate by 32 – 87%, 9 – 92%, 31– 98% and 31 – 98%, respectively. The PCN suppression increased with chitin inclusion rates. There were significantly higher values for soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, calcium, magnesium, potassium, and cation exchange capacity in soil amended with BSFCOF compared to unamended soil. This study demonstrates that BSFCOF fortified with 5% chitin is an effective soil enhancer with multiple benefits, including improved soil fertility, potato performance, and effective management of potato cyst nematodes.

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Kisaakye J., Beesigamukama D., Haukeland S., Subramanian S., Thiongo P.K., Kelemu S., Tanga C.M., Chitin-enriched insect frass fertilizer as a biorational alternative for root-knot nematode (Meloidogyne incognita) management, Frontiers in Plant Science, Vol. 15, March 2024

Root-knot nematodes (Meloidogyne spp.) are serious pests of most food crops, causing up to 100% yield loss. Nevertheless, commercial nematicides are costly and harmful to the environment. While the nematicidal potential of crustacean and synthetic chitin has been demonstrated globally, research on the potential of insect-derived chitin for nematode control has received limited attention. Here, seven chitin-fortified black soldier fly frass fertilizer extracts (chFE) were assessed for their suppressiveness of Meloidogyne incognita and impacts on spinach growth in comparison with a commercial nematicide using in vitro and in vivo bioassays. The performance of chFE and control treatments was assessed by determining their effects on nematode egg hatchability; infective juvenile (J2) mortality and paralysis; number of galls, egg masses, and J2s per plant; and spinach root and shoot biomass. In vitro results showed that chFE and commercial nematicide suppressed nematode egg hatchability by 42% and 52%, respectively, relative to the control (sterile distilled water). Up to 100% paralysis was achieved when M. incognita J2s were exposed to either chFE or commercial nematicide. Further, the J2 mortality achieved using chFE (95%) was comparable to the value achieved using commercial nematicide (96%); in all treatments, mortality increased with exposure time. Similarly, up to 85% suppression of gall development was achieved when spinach plants were grown in soil drenched with chFE; up to 79% reduction in egg mass formation and 68% suppression of J2 development in the root system were achieved using chFE. Also, chFE application significantly increased spinach root and shoot biomass by 54%–74% and 39%–58%, respectively, compared to commercial nematicide. Our findings demonstrate the nematicidal potential of chFE and its benefits on crop production. Thus, chFE could be considered as a promising multipurpose, regenerative, and cost-effective input for sustainable management of plant-parasitic nematodes and enhancement of crop yield.

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Kibet S., Kimani N.M., Mwanza S.S., Mudalungu C.M., Santos C.B.R., Tanga C.M., Unveiling the Potential of Ent-Kaurane Diterpenoids: Multifaceted Natural Products for Drug Discovery, MDPI Pharmaceuticals, Vol. 17, Issue 4, April 2024

Natural products hold immense potential for drug discovery, yet many remain unexplored in vast libraries and databases. In an attempt to fill this gap and meet the growing demand for effective drugs, this study delves into the promising world of ent-kaurane diterpenoids, a class of natural products with huge therapeutic potential. With a dataset of 570 ent-kaurane diterpenoids obtained from the literature, we conducted an in silico analysis, evaluating their physicochemical, pharmacokinetic, and toxicological properties with a focus on their therapeutic implications. Notably, these natural compounds exhibit drug-like properties, aligning closely with those of FDA-approved drugs, indicating a high potential for drug development. The ranges of the physicochemical parameters were as follows: molecular weights—288.47 to 626.82 g/mol; number of heavy atoms—21 to 44; the number of hydrogen bond donors and acceptors—0 to 8 and 1 to 11, respectively; the number of rotatable bonds—0 to 11; fraction Csp3—0.65 to 1; and TPSA—20.23 to 189.53 Ų. Additionally, the majority of these molecules display favorable safety profiles, with only 0.70%, 1.40%, 0.70%, and 46.49% exhibiting mutagenic, tumorigenic, reproduction-enhancing, and irritant properties, respectively. Importantly, ent-kaurane diterpenoids exhibit promising biopharmaceutical properties. Their average lipophilicity is optimal for drug absorption, while over 99% are water-soluble, facilitating delivery. Further, 96.5% and 28.20% of these molecules exhibited intestinal and brain bioavailability, expanding their therapeutic reach. The predicted pharmacological activities of these compounds encompass a diverse range, including anticancer, immunosuppressant, chemoprotective, anti-hepatic, hepatoprotectant, anti-inflammation, antihyperthyroidism, and anti-hepatitis activities. This multi-targeted profile highlights ent-kaurane diterpenoids as highly promising candidates for further drug discovery endeavors.

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Mokaya H.O., Mudalungu C.M., Tchouassi D.P., Tanga C.M., Techno-Functional and Antioxidant Properties of Extracted Protein from Edible Insects, ACS Food Science & Technology, Vol. 4, Issue 5, May 2024

Due to the recent increase in the human population and the associated shortage of protein resources, it is necessary to find new, sustainable, and natural protein resources from underutilized edible insects. This study sought to establish an optimized procedure for three extraction techniques [distilled water (E1), water with ultrasonic-assisted (E2), and chemical (E3): 0.25 M NaOH; pH 13.6] of protein from edible caterpillars (Gynanisa maja and Gonimbrasia belina) and cricket (Gryllus bimaculatus), and further to characterize the amino acid component and the techno-functional and antioxidant properties of the extracted proteins. The extraction efficiency of E3 was over 150%, with its proteins having higher oil- and water-holding capacities (3.69–5.75 and 2.36–3.08 g/g, respectively), foaming (foam capacity: 47–61%, foam stability: 17–84%), emulsion (emulsion activity: 41–51%, emulsion stability: 6–41%), and high amounts of essential amino acids. Protein extracts using E2 and E1 had higher solubility (>60%) over a wide pH range. The proteins and the hydrolysates obtained from the various insects through the different extraction methods had substantial antioxidative activities (<1.0 mg/mL). The hydrolysates from G. maja extracted by E3 and hydrolyzed by enzymes (pepsin + trypsin) had the highest antioxidant activity (56.7 μg/mL). The extraction approaches were feasible with unique specificity in their outcomes, which may benefit food industry in extraction and/or modification of edible insect protein in novel applications for different product formulations.

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Kariuki M.W., Barwani D.K., Mwashi V., Kioko J.K., Munguti J.M., Tanga C.M. , Kiiru P., Gicheha M.G., I.M., Partial Replacement of Fishmeal with Back Soldier Fly Larvae Meal in Nile Tilapia Diets Improves Performance and Profitability in Earthen Pond, Scientific African, Vol. 24, June 2024

Insect meals have the potential to be used as a source of nutrients in aquafeeds due to their high nutritional profile and cost effectiveness. The objective of this study was to elucidate the impact of black soldier fly larvae meal (BSFLM) as a replacement for fish meal (FM) on Nile tilapia (Oreochromis niloticus, L) growth performance, survival rate, somatic indexes and economic benefits. Four experimental diets were prepared; three with BSFLM as a substitute for FM at 25 % (T25 %), 50 % (T50 %) and 75 % (T75 %) and a control diet without BSFLM (T0 %, 100 % FM). A total of 360 fingerlings weighing about 20 – 30 gs each were assigned to twelve cages built in a 720m2 earthen pond, with 30 fingerlings in each cage in a completely randomized design with three replications in each treatment group. The fingerlings were fed the experimental diets for 26 weeks. The results showed that the treatment diets did not significantly affect body weight gain and daily feed intake (p > 0.05). However, treatment T50 % (52.16 g) had the highest body weight gain while treatment T75 % (46.00 g) had the lowest body weight gain even though not statistically different (p > 0.05). The body length also followed the same trend being higher in T50 % (16.50 cm) and lowest in T75 % (15.91 cm). The survival rate was significantly influenced (p < 0.05) by the diet treatment groups, while blood parameters, visceral somatic and hepatosomatic indexes did not vary significantly (p > 0.05) across the treatment diets. Return on investment and the cost-benefit ratio were significantly (p < 0.05) affected by the partial replacement of FM with BSFLM. Diets T25 %, T50 % and T75 % had higher (p < 0.05) profit margins when compared with diet T0 % (control). The study found that BSFLM can replace FM in diets for Nile tilapia without compromising on the growth performance of the fish while also increasing the profitability.

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Kyalo H., Tonnang H.E.Z., Egonyu J.P., Olukuru J., Tanga C.M., Senagi K., A convolutional neural network with image and numerical data to improve farming of edible crickets as a source of food—A decision support system, rontiers in Artificial Intelligence, Vol. 7, May 2024

Crickets (Gryllus bimaculatus) produce sounds as a natural means to communicate and convey various behaviors and activities, including mating, feeding, aggression, distress, and more. These vocalizations are intricately linked to prevailing environmental conditions such as temperature and humidity. By accurately monitoring, identifying, and appropriately addressing these behaviors and activities, the farming and production of crickets can be enhanced. This research implemented a decision support system that leverages machine learning (ML) algorithms to decode and classify cricket songs, along with their associated key weather variables (temperature and humidity). Videos capturing cricket behavior and weather variables were recorded. From these videos, sound signals were extracted and classified such as calling, aggression, and courtship. Numerical and image features were extracted from the sound signals and combined with the weather variables. The extracted numerical features, i.e., Mel-Frequency Cepstral Coefficients (MFCC), Linear Frequency Cepstral Coefficients, and chroma, were used to train shallow (support vector machine, k-nearest neighbors, and random forest (RF)) ML algorithms. While image features, i.e., spectrograms, were used to train different state-of-the-art deep ML models, i,e., convolutional neural network architectures (ResNet152V2, VGG16, and EfficientNetB4). In the deep ML category, ResNet152V2 had the best accuracy of 99.42%. The RF algorithm had the best accuracy of 95.63% in the shallow ML category when trained with a combination of MFCC+chroma and after feature selection. In descending order of importance, the top 6 ranked features in the RF algorithm were, namely humidity, temperature, C#, mfcc11, mfcc10, and D. From the selected features, it is notable that temperature and humidity are necessary for growth and metabolic activities in insects. Moreover, the songs produced by certain cricket species naturally align to musical tones such as C# and D as ranked by the algorithm. Using this knowledge, a decision support system was built to guide farmers about the optimal temperature and humidity ranges and interpret the songs (calling, aggression, and courtship) in relation to weather variables. With this information, farmers can put in place suitable measures such as temperature regulation, humidity control, addressing aggressors, and other relevant interventions to minimize or eliminate losses and enhance cricket production.

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Katchali M., Senagi K., Richard E., Beesigamukama D., Tanga C.M., Athanasiou G., Zahariadis T., Casciano D., Lazarou A., Unveiling Environmental Influences on Sustainable Fertilizer Production through Insect Farming, MDPI Sustainability, Vol. 16, Issue 9, April 2024

Entomocomposting is fast and environmentally friendly, boosts soil quality and crop production, and improves resilience to climate change. The black soldier fly larvae (BSFL) catalyze the composting process, but their efficiency is highly influenced by environmental factors and the quality of the substrate. This study employs response surface methodology to discern physical–chemical factors that influence the nutrient quality of BSF frass fertilizer. Internet of Things (IoT) sensors were deployed to monitor in real-time both independent variables (air temperature, moisture content, humidity, and substrate temperature) and dependent variables (nitrogen, phosphorous, and potassium); the data were relayed to the cloud. A non-linear regression model was used to study the relationship between the dependent and independent variables. Results showed that air humidity and air temperature did not have a significant effect on nitrogen and phosphorus accumulation in frass fertilizer, respectively, but phosphorus was significantly influenced by air humidity. On the other hand, neither air temperature nor moisture content has a significant effect on potassium concentration in frass fertilizer. We found that an air temperature of 30 °C and 41.5 °C, substrate temperature of 32.5 °C and 35 °C, moisture content between 70 and 80%, and relative humidity beyond 38% can be conducive for the production of high-quality BSF frass fertilizer. Model validation results showed better robustness of prediction with 𝑅2 values of 63–77%, and 𝑅2adj values of 62–76% for nitrogen, phosphorous, and potassium. Our findings highlight the potential for the application of digital tools as a fast and cost-effective decision support system to optimize insect farming for the production of high-quality frass fertilizer for use in sustainable agriculture and crop production.

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Conference papers

Issa A., Poole C., Darwazeh I., Cassava starch measurement in the field - evolution of a low-cost test instrument with wireless connectivity, 2023 IEEE AFRICON, September 2023

The evolution in design philosophy for a portable test instrument for estimating the starch content of cassava roots is described. The instrument uses a radio frequency reflectometry technique to measure return loss using a coaxial probe. An on-board microprocessor then determines the starch content of the cassava sample based on a pre-stored calibration table. The design evolution started with a minimum viable hardware platform that was used for proof of concept and to gather preliminary field data. The next generation added wireless connectivity for cloud data collection and analysis, user interface improvements and rechargeable battery capability. Design focus then shifted to cost reduction, robustness and suitability for mass production so that the instrument can be put into the hands of farmers.

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Odedeyi T., Darwazeh I., New Insights on Application of Return Loss Measurement for Starch Content Estimation in Cassava, 2023 IEEE AFRICON, September 2023

This research explores the use of radio frequency (RF) return loss measurement to characterize cassava quality and estimate the starch content of cassava roots, with new equivalent circuit models presented. While pure starch is non-conductive, the content of charged ions in the raw composite cassava flour provides a potential marker for estimating the starch content of cassava, which is important for the design of quality measurement devices based on the return loss method. The study also raises questions for further exploration, such as understanding the pattern of distribution of the electrolytic components in a fresh root and exploring the relationships between these ions and other properties of cassava. Overall, these new findings offer new directions for research and development in the field of food quality assessment.

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Anedo E.O., Mochoge B., Korir N.K., Beesigamukama D., Haukeland S., Cheseto X., Nyongesa M., Subramanian S., Tanga C.M., Exploring the potential of black soldier fly-composted frass fertilizer in the control of nematodes and boosting potato yields in Africa, INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

Potato production in Africa is highly affected by low soil fertility and nematode infestation. The use of mineral fertilizers and synthetic nematicides remains unsustainable due to high costs and negative impacts on humans and environmental health. This study assessed the potential of black soldier fly-composted frass fertilizer (BSFCFF) in the management of potato cyst nematodes and enhancing potato yield under open field conditions.

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Ouma L.O., Muthomi J.W., Kimenju J.W., Beesigamukam D., Subramanian S., Tanga C.M., Insecticidal potential of chitin-enhanced black soldier fly frass fertilizer extracts against onion fly (Atherigona orientalis Schiner), INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

Bulb onion is among the most consumed vegetables in Sub-Saharan Africa, but its production is significantly constrained by soil-dwelling pests, especially the onion root flies that double as vectors. This study evaluated the insecticidal potential of chitin-enhanced black soldier fly (BSF) frass fertilizer extracts as a sustainable alternative for management of the onion fly pest.

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Chepkorir A., Gitari H.I., Beesigamukama D., Subramanian S., Ekesi S., Tanga C.M., Using insect-composted organic fertilizer to increase yield and economic returns of bush beans (Phaseolus vulgaris), INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

Black soldier fly frass fertilizer (BSFFF) has gained global prominence due to its potential to enhance soil health and crop production. However, there is limited knowledge about its performance on leguminous crops. This study evaluated the comparative effect of BSFFF and other commercial fertilizers on the growth, yield and profitability of bush beans (Phaseolus vulgaris L.) (Rosecoco GLP2).

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Tanga C.M., Kababu M.O., Beesigamukama D., Subramanian S., Insect Farming Innovations: Lessons from Africa, INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

In Africa, insect farming is a rapidly growing agribusiness, coupled to the rising demand for alternative proteins for food and feed. This review highlights the status and emerging gaps in edible insect farming, role of private sectors, potential estimates; processing, nutritional composition, safety, application, and legislative framework governing the industry.

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Kassie M., Abro Z., Tanga C.M., Sevgan S., Socioeconomic and ecological impact of insect farming in sub-Saharan Africa, INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

The increasing human population, income growth, and urbanization trends in sub-Saharan Africa (SSA) have led to a consistent rise in the demand for animal-sourced food. Simultaneously, rapid urban expansion produces significant quantities of biowaste, posing ecological and food security challenges. The COVID-19 pandemic, coupled with regional geopolitical conflicts, further disrupted the already delicate food, feed, and fertilizer markets, shedding light on Africa’s fragile food system.

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Beesigamukama D., Subramanian S., Tanga C.M., Efficiency of garden fruit chafers to recycle animal manure: Implications on fertilizer quality, pathogen suppression and crop yield, INSECTA 2023 International Conference, Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Book of abstract, September 2023

The role of insects as nature-based recyclers have given rise to captive mass rearing worldwide. However, no information exists on transformative ability of garden fruit chafer (Pachnoda sinuata L.) to recycle waste into value added products. This study evaluated the nutrient quality, maturity, stability, and agronomic effectiveness of P. sinuata composted fertilizer on vegetable production and associated nutrient quality.

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