Efforts to recycle organic waste using black soldier fly (BSF) larvae into high-quality alternative protein ingredients in animal feeds and organic fertilizers have gained momentum worldwide. However, there is limited information on waste manipulation to increase nutrient retention for enhanced larval performance and frass fertilizer quality. In the present study, brewer's spent grain with a carbon to nitrogen (C/N) ratio of 11 (control) was amended with sawdust to obtain substrates with C/N ratios of 15, 20, 25 and 30. The effects of substrate C/N ratios on BSF larval yield, waste degradation, biomass conversion efficiency, compost maturity and nutrient levels of frass fertilizer were evaluated. Substrates amended with sawdust did not significantly affect waste degradation efficiency and biomass conversion rates of BSF larvae. The wet and dried larval yields were significantly higher for substrates with C/N ratio of 15 compared to the other amended substrates. An amended substrate with C/N ratio of 15 enhanced nutrients uptake by BSF larvae, and increased nitrogen (N) and phosphorus retention in frass compost by 21 and 15%, respectively. Compost maturation time was shortened to five weeks, as indicated by the stable C/N ratios and high seed germination indices. This study has demonstrated that the amendment of the substrate with sawdust to C/N ratio of 15 could generate compost with desirable nutrients for use as high-quality fertilizer for organic farming.

Arthropod pests and vectors constrain the livelihood opportunities of people in Africa by debilitating production of crops and livestock and through transmission of vector-borne diseases. In the absence of effective alternative management options to tackle these pests and vectors, there is extensive dependence on synthetic pesticides for their management on crop and livestock systems, with significant negative impacts on animal and human health, and the environment. Biopesticides are effective and environmentally sustainable alternatives to synthetic pesticides. At the International Centre of Insect Physiology and Ecology (icipe), the Arthropod Pathology Unit (APU) was established for effective biopesticide research-for-development (R4D), underpinned by a large repository of arthropod pathogens, protocols for lab bioassays and field efficacy testing, and an effective public-private partnership to generate new biopesticide products. The focus of icipe's APU has gradually transformed from basic to applied research leading to innovative, commercial products. Among the insect pathogens, greater focus has been placed on fungi, especially Metarhizium anisopliae, against key crop and livestock pests. Presently, three biopesticides based on M. anisopliae strains researched by icipe have been commercialized by Real IPM (Thika, Kenya) and are used on 132,994 ha in sub-Saharan Africa, with registration of additional products against animal ticks and the fall armyworm Spodoptera frugiperda pending. Our R4D activities on arthropod pathogens increasingly include bacteria, microsporidia, entomopathogenic nematodes and viruses. Recently, icipe is expanding R4D toward plant endophytes and rhizosphere inhabitants. The Centre also embarked on understanding the diversity, roles and possible exploitation of insect symbionts in key plant pest and disease vectors. In addition, key entomopathogens of reared insects for human food and animal feed need to be identified and controlled through high hygiene standards during rearing. Further, research is aimed at integrating biopesticides not only with other integrated pest management (IPM) technologies but also with pollination services.

The use of black soldier fly frass fertilizer (BSFFF) is being promoted globally. However, information on nitrogen (N) fertilizer equivalence (NFE) value and synchrony of N mineralization for crop production remains largely unknown. Comparative studies between BSFFF and commercial organic fertilizer (SAFI) were undertaken under field conditions to determine synchrony of N release for maize uptake. The BSFFF, SAFI, and urea fertilizers were applied at the rates of 0, 30, 60, and 100 kg N ha⁻¹. The yield data from urea treated plots were used to determine the NFE of both organic inputs. Results showed that maize from BSFFF treated plots had higher N uptake than that from SAFI treated plots. High N immobilization was observed throughout the active growth stages of maize grown in soil amended with BSFFF, whereas soil treated with SAFI achieved net N release at the silking stage. Up to three times higher negative N fluxes were observed in SAFI amended soils as compared with BSFFF treated plots at the tasseling stage. The BSFFF applied at 30 and 60 kg N ha⁻¹ achieved significantly higher NFE than all SAFI treatments. Our findings revealed that BSFFF is a promising and sustainable alternative to SAFI or urea for enhanced maize production.

Sustainable agricultural technologies have impacted positively on staple crop yields in Asia and some parts of Sub-Sahara Africa. However, the adoption of similar technologies in vegetable subsector is still low among small-scale farmers in Tanzania. Several efforts aimed at promoting the adoption of the technologies such as improved vegetable varieties, mineral fertilizers, manure and pest management practices to raise output, have not yielded the desired impacts. We examine dynamics of farmers’ adoption of these technologies and the factors influencing technology choice. We also predict the peak level and speed of adoption of these sustainable technologies. Findings show that complementarities exist among improved varieties, fertilizers and pest management practices, while tradeoffs exist between manure and mineral fertilizers. These complementarities and tradeoffs should be sufficiently exploited for farmers to adopt technologies that are suited for their specific circumstances. Better knowledge, access to credit, group membership, farmer participation in demonstration trials, and, more substantial livestock holdings drive technology adoption decision. Technologies have different peak levels of adoption, which are reached at different time intervals. The policy option is to strengthen collaborative efforts to scale out sustainable agricultural technologies to respond to the increasing demand for nutrient-dense vegetables for income, food and nutrition security.

In the laboratory, the pathogenicity of thirteen isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and two isolates of Beauveria bassiana (Balsamo) Vuillemin against the melon fly Zeugodacus cucurbitae (Coquillett) were assessed by exposing adults to 0.3 g of dry conidia (~3 × 10⁹ conidia) of each isolate for 5 min and monitoring mortality for up to 5 days. Compatibility with a male pheromone, cuelure, (4-(p-acetoxyphenyl)-2-butanone), was determined by testing conidial germination and germ tube growth of the most promising isolate, M. anisopliae ICIPE 69, in the presence of cuelure at different temperatures. For horizontal transmission, the flies were separated by sex, separately exposed to M. anisopliae ICIPE 69, and subsequently mixed with non-exposed flies from the other sex. The most pathogenic isolates were M. anisopliae ICIPE 69, 18, and 30, causing mortalities of 94, 87, and 81%, with 5 days post-exposure, respectively. Metarhizium anisopliae ICIPE 69 caused the highest pupal mortality of 74%, with 15 days post-exposure. Horizontal transmission of M. anisopliae ICIPE 69 among male and female Z. cucurbitae was confirmed by 59 and 67% mortality after exposure to infected donor males and females, respectively. Metarhizium anisopliae ICIPE 69 affected the oviposition, but not hatchability, of infected Z. cucurbitae females. Metarhizium anisopliae ICIPE 69 is, therefore, a potential isolate for biopesticide development for Z. cucurbitae management in cucurbit production systems.