Nutritional composition of edible wood borer beetle larvae in Kenya.

Exploration of edible insects as sustainable alternative nutrient-dense sources such as nutraceuticals have attracted more and more global attention recently. However, research on wood borer beetles have largely been overlooked. This study assessed the entomo-chemical properties of Titoceres jaspideus (Cerambycidae) and Passalus punctiger (Passalidae), which are widely consumed in many African countries, including Kenya. The crude protein content of the beetle larvae ranged between 27.5-39.8 mg BSA/g. In comparison with those of cereals, amino acids such as lysine (7.9-9.9 mg/g), methionine (0.48-0.64 mg/g) and threonine (2.31-2.55 mg/g) were considerably high in the larvae. Methyl-5Z,8Z,11Z,14Z-eicosatetraenoate and methyl-9Z-octadecenoate were the predominant polyunsaturated and monounsaturated fatty acids, respectively. High total phenols (>4.4 mg GAE/g), flavonoids (>3.6 mg QE/g) and anti-oxidative activities (>67%) were recorded for both larvae. This implies that increasing the consumption of wood-borer beetle larvae would positively impact the state of the natural environment and reduce the problem of malnutrition in the society. Thus, applying these strategies to develop insect food in a more familiar form can help to make insect-enriched foods more appealing to consumers, facilitating their widespread adoption as a sustainable and nutritious food source.

Unlocking the Potential of Substrate Quality for the Enhanced Antibacterial Activity of Black Soldier Fly against Pathogens.

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 againstB. 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.

Potential of Insect Life Stages as Functional Ingredients for Improved Nutrition and Health.

This study aimed to provide information on the nutrients of the edible larval stage of Gonimbrasia cocaulti (GC) for the first time, while exploring the potential nutrient content of the pupal life stages of the domestic silkworm (Bombyx mori; BM) and the Eri silkworm (Samia Cynthia ricini; SC). The three insects were analyzed for fatty acids, minerals, proximate composition and vitamins. Among the fatty acids, linoleic, a polyunsaturated fatty acid, was approximately threefold higher in GC than in the silkworms. The Ca, Fe and K contents were highest in GC. However, the Zn and Na contents were highest in BM, while Mg content was predominant in SC. The crude protein content of the various developmental life stages of the edible caterpillars and pupae ranged between 50 and 62%. Further, the fiber content of GC was substantially higher compared to the pupal stages of the two silkworm species. The vitamin (B6, B9, B12 and α-tocopherol) levels of the two insect life stages were considerably high. These insects are comparably rich in nutrients with potential suitability to be utilized in food fortification and thus ease pressure on the over-reliance on animal and plant-based sources, which are becoming unsustainable.

Differences in the biochemical content and radical scavenging activity of propolis from different parts of a Meliponula ferruginea hive.

Research on stingless bee products has increased in recent years, and of particular interest is propolis because of its biological activities such as antioxidant and antimicrobial. However, there is paucity of information regarding intra-hive variations in the biochemical composition and biofunctional properties of this propolis. In this study, we investigated the phytochemicals and radical scavenging activity (RSA) of Meliponula ferruginea propolis from 10 wooden hives (n = 49). The samples were collected from five different locations comprising the entrance, involucrum, pillars, pots and sealant. Principal component analysis showed that there is an intra-hive variation in phytochemical content and RSA. Phenolic content constituted the highest phytochemical content in all the locations. The sealant and entrance had the highest amounts of phytochemicals compared to the involucrum, pillars and pots. Further analysis of propolis extracts by gas chromatography-mass spectrometry revealed occurrence of different compounds such as monoterpenoids, hydrocarbons, triterpenoids and alkaloids. Hydrocarbons were common in all parts while monoterpenes and triterpenes were present in the entrance. The findings of our study indicates that there is an intra-hive variation in propolis of M. ferruginea and hence this information will provide further insight into better understanding of stingless bee propolis.

Characterization of honeys produced by sympatric species of Afrotropical stingless bees (Hymenoptera, Meliponini).

We investigated the effect of bee species identity and harvesting methods on the chemical composition and antiradical activity of 53 honey samples, produced by six stingless bee species in western Kenya (Kakamega forest). Our results illustrate that none of the assayed parameters significantly varied between the honey samples harvested by "punching holes" (n = 25) and "squeezing" (n = 28) methods. By contrast, species identity drove significant differences in the assayed parameters. Positive correlations between the antiradical activity and the phytochemicals (phenols and flavonoids) were observed, and honeys from Liotrigona sp. exhibited the highest amounts of phenols (214 mg GAE/100 g), flavonoids (73.0 mg QE/100 g) and antiradical activity (76.2%). The physicochemical analyses confirm the need to establish separate stingless bee honey standards for moisture, free acidity, invertase, electrical conductivity, and HMF, as these parameters significantly diverged from the set limits for Apis mellifera honey.

Phytochemical composition and bio-functional properties of Apis mellifera propolis from Kenya.

There is an increased demand for natural products like propolis, yet little information is available about the chemical composition of African propolis and its bio-functional properties. Therefore, in this study, we aimed to quantify the phytochemicals and determine the antioxidant and antimicrobial properties of Apis mellifera propolis (n = 59) sourced from various regions in Kenya. Principal component analysis (PCA) showed that the sampling region had a remarkable impact on the propolis's composition and bio-functional properties. Generally, the propolis contained high amounts of phytochemicals, particularly alkaloids (5.76 g CE/100 g) and phenols (2.24 g GAE/100 g). Furthermore, analysis of propolis by gas chromatography-mass spectrometry (GC-MS) revealed various compounds with varying bio-functional activities. These compounds included triterpenoids alpha- and beta-amyrin, oleanen-3-yl-acetate, urs-12-en-24-oic acid, lanosta-8,24-dien-3-one, and hydrocarbons tricosane and nondecane, which have been reported to have either antimicrobial or antioxidant activities. The propolis samples collected from hotter climatic conditions contained a higher composition of phytochemicals, and additionally, they displayed higher antioxidant and antimicrobial activities than those obtained from cooler climatic conditions. Key findings of this study demonstrate the occurrence of relatively high phytochemical content in Kenya's propolis, which has antioxidant and antimicrobial properties; hence this potential could be harnessed for disease control.

Bioactive constituents, in vitro radical scavenging and antibacterial activities of selected Apis mellifera honey from Kenya.

There is limited information about the relative composition and health benefits of various honey consumed across Africa. This study aimed at estimating the bioactive constituents, in vitro radical scavenging and antibacterial activities of 16 kinds of honey obtained from different geographical locations in Kenya. Manuka 5 + honey was included for comparison. Some of the tested honey had biochemicals and bioactivities similar to or higher than Manuka 5 + honey. The honey exhibited DPPH radical scavenging ability, with several types of honey showing superior scavenging potential than Manuka 5 + honey, owing to their high phenol content. All types of honey inhibited the growth of E. coli and further showed a substantial amount of nonperoxide antimicrobial activity. The geographical origin of honey had an influence on its bioactive contents. Overall, these findings suggest that Kenyan honey has great therapeutic potential, and thus, its clinical application should not be overlooked.