Canarium Schweinfurthii Research Articles

Nutraceutical and Functional Food Potentials of African Black Elimi (Canarium schweinfurthii): A Review

Study’s Excerpt The potentials of Canarium schweinfurthii in traditional African medicine in treating various ailments due to its rich bioactive composition is extensively explored. 80 publications were synthesized to gather the plant’s diverse nutraceutical and functional properties. The plant has antimalarial, anti-cancer, and antioxidant effects, among others. Full Abstract Medicinal plants have been central to African traditional medicine for centuries, preceding the development of synthetic drugs. Africa is blessed with large medicinal plants that are either under-explored or yet to be studied. This study aimed to find relevant research works on Canarium schweinfurthii with the purpose of identifying a new research niche. One hundred eighteen (118) research journals were collected, and 80 publications were synthesized and used to identify non-repeated experiments on the functional and nutraceutical potentials of Canarium schweinfurthii. The results of the review revealed that different parts of the plant including leaves, stem bark, roots, fruits, seeds, flowers, gum, and resin were traditionally employed in treating a range of ailments, including diabetes, stomach ulcers, malaria, typhoid, leprosy, reproductive disorders, and fever which are attributed to plant’s richness for nutraceutical and functional properties, driven by the presence of bioactive compounds such as antioxidants, alkaloids, saponins, flavonoids, tannins, glycosides, and phenolic compounds. Nutraceutical and functional investigations of the plant have corroborated the antimalarial, anti-cancer, anti-diabetic, analgesic, antioxidant, antimicrobial, anti-bacterial, growth-promoting, nephroprotective, food preservative, anthelmintic, and termiticidal properties of the fruit pulp, fruit bark, stem bark, fruit oil, seed oil of Canarium schweinfurthii. This review recommends the plant for proper establishment of a foundation for the plant’s pharmaceutical application and underscores the need for further research.

Pyrolysis of metal oxides treated Canarium schweinfurthii Shell: Investigation of thermogravimetric kinetics and thermodynamics

Metal oxides as catalysts alter the properties of the pyrolysis vapor secondary reactions during the thermal decomposition of several biomass leading to high-value bio-oils. This study aimed to investigate the thermal decomposition characteristics of Canarium Schweinfurthii (CS) shells that were treated with various metal oxides (ZnO, CuO, Fe2O3/FeO, and Fe2O3) using pyrolysis. The study also sought to identify pyrolysis reaction parameters (kinetics and thermodynamics parameters) that are not widely documented. Thermogravimetric pyrolysis was carried out at different heating rates, and the undocumented pyrolysis kinetic parameters were determined using the Flynn-Wall Ozawa method (FWO) according to American Standard Testing and Materials (ASTM) 6441 guidelines for assessing biomass decomposition. The metal oxide-treated CS shells lost significant weight between 62 and 67 wt% during the thermogravimetric pyrolysis, lower than 75 wt% of the CS shell. The average activation energies (Eα) for pyrolysis of the ZnO, CuO, Fe2O3/FeO, and Fe2O3 treated CS shells were 203.04, 155.35, 338.85, and 219.92 kJ/mol, respectively in contrast to that of the untreated CS-shell. The Bayesian Information Criteria revealed that the diffusion kinetics of the Gistling-Brounshtein model best describes the pyrolysis of the shell mixed with metal oxides. The metal oxides affected the CS shells' pyrolysis kinetic parameter (Eα), which can promote pyrolysis vapor upgrading to encourage the widespread use of metal oxides in pyrolysis for bioenergy and chemical recovery.

In Vivo and In Vitro Anti-Hyperglycemic and Hypolipidemic Effect of Atili (Canarium Schweinfurthii) on Streptozotocin Induced Diabetic Rats

Canarium schweinfurthii is used as a traditional treatment for diabetes mellitus in Nigeria and other African countries, according to ethnobotanical records. However, scientific evidence has not yet been published. This study aimed to evaluate the antidiabetic effects of Canarium schweinfurthii fruit pulp ethanol extract in streptozotocin-induced diabetic rats. A type II diabetic rat model (TDRM) was established via high-fat diet and Streptozotocin induced diabetes. Diabetic rats were randomized into five different groups; the control group (n = 6) (common diet) and high-fat diet (HFD) groups fed with ethanolic extract at 100, 200, 400, and 600 mg/ml (n = 24). At these doses, the blood glucose was lowered by 57.68% to 80.17%. For hypolipidemic test, total cholesterol was lowered from 162.33 mg/dL to 70.19 mg/dL; Glyceride from 166.91 mg/dL to 68.61mg/dL. Creatinine from 6.77 mg/dL to 6.42 mg/dL. Alanine Aminotransferase was 151.3 to 53.31 µI/L in 600mg group. Aspartate Aminotransferase enzyme decrease from 130.4 µI/L to 40.81 µI/L. This study confirmed the antidiabetic effects of Canarium schweinfurthii fruit extract.

ECOLOGICAL AND FUNCTIONAL COMPARISON OF WOOD ANATOMY ON SOME TREE GENERA IN THE SOUTHERN NIGERIA

This work aimed at utilizing wood anatomical traits to assess the compatibility or suitability of 9 species in the families where they belong since the earlier classification depended only on morphological characters and also to possibly deduce the permeability of their vessel lumen during wood treatment with preservatives of equal or different viscosity. Comparative stem anatomy of tree taxa Antiaris toxicaria Lesch. (Moraceae), Ficus exasperate Vahl. (Moraceae), Milicia excelsa Welw. (Moraceae), Dacryodes klaineana Lam. (Burseraceae) Canarium schweinfurthii Engl. (Burseraceae), Dacryodes edulis Lam. (Burseraceae), Erythrophleum suaveolens Taub. (Fabaceae), Pelthophorum pterocarpum De Cand. (Fabaceae), Pterocarpus soyauxii Taub. (Fabaceae) was studied. Observations on the transverse, radial-longitudinal and tangential-longitudinal sections showed that there were vast variations and few similarities in the vessel, axial parenchyma, ray cell and storied fibre distributions within and across families. Variations across the three ecological zones were found. The highest vessel diameter occurred in C. schwenfortii with 222.84µm (Burseraceae) followed by F. Exasperate with 196.42 µm (Moraceae) and P. pterocarpum with 187.23 µm (Fabaceae) across the three ecological zones. Vessel diameters were in direct proportion with the amount of rainfall while vessel frequencies were in negative proportion with the amount of rainfall across the ecological zones. Qualitative properties were not significantly affected by either temperature or rainfall.

Dynamics of soil organic carbon pools following conversion of savannah to cocoa agroforestry systems in the Centre region of Cameroon

Afforestation of gramineous-woody savannah with cocoa agroforestry systems (cAFS) is a common farmer practice in Cameroon considered as sustainable. Nevertheless, the effects of afforestation of savannah with cAFS on soil organic carbon (SOC) turnover and content, and the factors controlling SOC accumulation and stabilization are unknown. SOC content at 0–10 cm soil layer, and SOC distribution in soil particle size fractions (0–20 μm fraction considered as mineral-associated organic carbon, MAOC; 50–2000 μm considered as particulate organic carbon, POC; and 20–50 μm), were compared in different systems settled on degraded savannah (orthic ferralsols). These systems included annual cropland (≈ 5 years old), cocoa monoculture (≈10 years old), and cAFS (from 20 to 60 years old) including different shade tree species such as Albizia adianthifolia, Canarium schweinfurthii, Dacryodes edulis, Milicia excelsa and Ceiba pentandra. Savannah and nearby secondary forest patches were also included in the design as controls. Soil 13C was analysed to investigate the soil carbon turnover after afforestation (C3 plants) of gramineous savannah (C4 plants).SOC significantly increased in the 0–10 cm depth from 10.6 ± 3.1 g C kg−1 in degraded savannah to 17.9 ± 5.6 g C kg−1 in cAFS reaching similar levels as in nearby secondary forests (16.3 ± 5.8 g C kg−1), while annual cropland and cocoa monoculture presented a non-significant decrease in SOC content. These changes were due to rapid loss of SOC derived from savannah plants (C4) – about 76% within the first 15 years after conversion, and higher gain of SOC derived from C3 plants in cAFS than in the other land uses (e.g. from 3.4 ± 1.5 g C kg−1 in savannah to 17.8 ± 5.7 g C kg−1 in cAFS). This SOC enrichment in cAFS was distributed in POC (64%), MAOC (30%) and the intermediate 20–50 μm soil fraction (6%). The higher annual litter input accumulated on a longer period in cAFS (20 to 60 years) than in cocoa monoculture (10 years) concomitant with the lower litter recalcitrance of associated trees compared to cocoa could explain the higher enrichment of SOC in all fractions in cAFS. The soil pH and exch. Ca2+ differed under the different shade tree species, and were positively correlated to SOC content. The highest contents of soil exch. Ca2+ induced by Ceiba and Milicia in the top 10 cm soil layer could contribute to increase SOC enrichment under those species through soil aggregation and related C stabilization. We found no strong evidence of the effect of soil texture on additional soil carbon accumulation in cAFS, especially for the more stable C pool (MAOC). Our results evidenced that savannah afforestation with cAFS appears as a valuable option for top soil carbon enrichment and should consider tree species associated to cocoa to enhance soil C sequestration, soil quality and cocoa production sustainability.

Effect of edible coating made from plantain peel waste on the quality of African elemi (Canarium schweinfurthii) fruit

Effect of edible coating made from plantain peel waste on the quality of African elemi (Canarium schweinfurthii) fruit

Evaluating Thermal Performance and Environmental Impact of Compressed Earth Blocks with Cocos and Canarium Aggregates: A Study in Douala, Cameroon

A novel low-cost earthen construction system integrating biosourced aggregates is proposed for houses’ erection of low-income households. This study is based on in-situ measurements on two representative test cells constructed in Douala, with a typical hot and humid climate. One of these buildings is made with a hollow cement block as a reference, and the other with biosourced earth bricks modified with Cocos nucifera and Canarium schweinfurthii aggregates. Dynamic thermal simulations of the two test cells were performed using the EnergyPlus building performance simulation program. The results are based on measuring air temperature and humidity, and the simulation leads to defining the discomfort hours and the annual energy consumption. The adaptive ASHRAE 55 thermal comfort model was used to evaluate the comfort conditions. The results show that air conditioning systems provide the best comfort systems with minimums of about 95% for plastered and unplastered wall construction systems. Biosourced compressed earth brick constructions offered the best thermal performance with comfort ranges of around 96% and 44% for air conditioning and natural ventilation, respectively. In terms of energy consumed, there was a gain of about 100 kWh over the year. Energy consumption is lower in the biosourced compressed earth brick building than in the hollowed cement block building: this one offered the lowest comfort range of about 40% in natural ventilation. The construction provisions were considered for the life cycle assessment, and two scenarios describing the origin of the cement raw materials were considered. It can be seen that cement accounts for more than 95% of the impacts for both construction systems, as well as for the scenarios of its origin. In all situations, the hollowed cement block construction presented the highest impact on the global warming potential: 66 KgCO2eq and 89 KgCO2eq, respectively, without plaster and with plaster. It can also be seen that the plastered layer had a carbon footprint (in terms of Green House Gas Emissions (GHG emissions)) of almost 40% on the overall functional unit. Canarium Schweinfurthii and Cocos Nucifera materials accounted for only 1% of the overall impact.

Investigating the Pozzolanic Properties of Canarium schweinfurthii (‘Atili’) Seed Shell Ash as Partial Replacement for Cement in Concrete

Ethnomedicinal, insecticidal, biological and other non-engineering uses of Canarium seed have been identified but little or no engineering uses have been explored. This research investigates the effect of Canarium schweinfurthii Seed shell Ash (CSSA) on the mechanical properties of concrete. CSSA was obtained after calcination of Canarium schweinfurthii seed shell at 4000C, 7000C and 1000 0C. X-ray Florescence (XRF) analysis carried out revealed the best sample of CSSA to be used for this work, and found to be a Class C pozzolana, which contains 51.21% of (SiO2 + Al2O3 + Fe2O3). The compressive and flexural strengths were determined at 7, 14, 21 and 28 days. The workability of the concrete was found to have dropped with the increment in the percentage of CSSA in the concrete. The compressive strength and flexural strength of the concrete cubes declined with the increment in the percentage of CSSA in the concrete. The compressive strength of the CSSA concrete after each curing age for the control and all the different percentages of CSSA replacement all met the minimum requirement for the characteristic strength (20 N/mm2). From the result, the reduction in compressive strength of the concrete at 28 days is between 0% and 5%, with the optimal increment in the strength achieved at 10% CSSA. The flexural strength of the CSSA concrete reduces drastically with increment in the CSSA content across all the curing ages, having an optimal replacement at 5% CSSA replacement.

Experimental thermophysical dependent mechanical analysis of earth bricks with Canarium schweinfurthii and Cocos nucifera bio-aggregates - A case study in Cameroon

In order to meet sustainable development goals, global policies are strongly oriented towards the recovery of local materials such as agricultural waste. In this context, a new biosourced compressed earth brick (CEB) has been produced with bio-shell aggregates of Cocos nucifera (CN) and Canarium schweinfurthii (CS), added in equal proportions for various mixtures. The main objective is to study, on one hand, the effect of CN and CS aggregates on the mechanical behaviour and the thermo-physical properties of the CEB. On the other hand, durability of CEB was investigated in terms of hydric stability, abrasion resistance and hygro-thermo-mechanical behaviour. Mixtures were prepared using earthen material and 0, 5, 10 and 15 wt% CNCS, with 8 wt% cement CEM II-B-LL 42.5, respectively. Wet and dry compressive strengths are evaluated versus compaction pressure (2.5, 5, 7 and 10 MPa). The increase of CNCS aggregate content induced a reduction of the compressive strength in both wet a\nd dry situations whatever the compaction pressure. The samples with 5 wt % CNCS and 8 wt % cement, however, offered performances close to reference samples without CNCS aggregates. The reverse trend was found for thermal conductivity: thermal conductivity of the bio-sourced CEB is below 1 W·m−2·K−1 which means good insulating performances. It is noted that the modified CEB have relatively low water absorption, which contribute to a good durability. Hygro- and thermo-mechanical tests showed however a quasi-linear decrease of compressive strength when the humidity of the environment increases but also when the temperature rises. At the end, to obtain more accurate properties by prediction, some machine learning models were used.

Peasants' perceptions on the socioeconomic importance and cultivation practice of Canarium schweinfurthii Engl. (Black olive tree) in the Western Highlands of Cameroon

Canarium schweinfurthii is one of the agro-forestry tree species with multiple uses in the subtropical countries which is still exploited wild. The purpose of this study was to get insights related to peasants' perceptions on the socio-economic importance and cultivation practice of the species in the Western Highlands of Cameroon. The methodology consisted of surveys among people spread over 7 villages. Two hundred (200) people who were involved in C. schweinfurthii exploitation were selected in the study area following a random approach and interviewed using a structured questionnaire. In addition to the identification of respondents, the information collected from interviewees focused on: 1) knowledge, uses, harvesting methods and the impact of the exploitation of the species on the well-being of people; 2) the trend of the population’s dynamics of the species and, 3) the know-how and practices in the cultivation of the plant. The results showed that almost all the interviewees (99%) knew the species that they exploit in six categories of use (food, medicine, handicraft, construction, timber industry and firewood supply), with a broad consensus (Cs = 0.98) for the use in food. The degree of consensus remained low for its use in medicine (Cs= -0.18), firewood supply (Cs= -0.21), timber industry (Cs= -0.65), construction (Cs= -0.77) and handicrafts (Cs= -0.84). According to 80% of respondents, income from the sale of the fruits significantly contributes to household welfare. The most cited harvesting method was fruits picking, which does not endanger the species. Only 37% of the interviewees perceived a regressive trend in the dynamics of the species' population over the last decade. For 71% of the respondents, the cultivation practice by farmers is rare or even non-existent. The main reasons for non-cultivation of the species are the uncertainty that the planted trees will bear fruits (80% of respondents) and the long duration of the vegetative growth phase (55% of respondents). 90% of respondents expressed their willingness to adopt the cultivation of the species if these constraints are circumvented. These findings showed that C. schweinfurthii would be an interesting candidate for participatory domestication in the Western Highland of Cameroon, for the intensification of agro-forestry systems. For this purpose, the establishment of an efficient protocol for asexual propagation of fruit-producing individuals is needed.

Pyrolysis of Canarium schweinfurthii hard-shell: Thermochemical characterisation and pyrolytic kinetics studies

Canarium schweinfurthii fruit used in food and cosmetics produces waste nuts with a hard shell (hard-shell) and kernel. The hard-shell contained lignin and holocellulose, besides 51.99 wt% carbon, 6.0 wt% hydrogen, 41.68 wt% oxygen, and 70.97 wt% volatile matter. Therefore, this study commenced thermochemical investigations on the hard-shell through extensive intermediate pyrolysis and kinetic studies. During the active stage of thermogravimetric pyrolysis, the hard-shell lost a maximum of 56.45 wt%, and the activation energies obtained by the Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Starink methods were 223, 221 and 217 kJ/mol, respectively. The Flynn-Wall-Ozawa method depicted the degradation process accurately, where the Coat-Redfern method's contraction and diffusion mechanisms governed the pyrolysis reactions at activation energies of 16.62 kJ/mol and 38.83 kJ/mol, respectively. The pyrolysis process produced 25 wt% biochar and 25 wt% bio-oil under optimum conditions. The calorific values of the bio-oils with 6.81–7.11 wt% hydrogen and 68.01–71.12 wt% carbon was 26.32–27.83 MJ/kg, with phenolics and n-hexadecanoic and oleic acids as major compounds. Biochar, by contrast, has a high carbon content of 75.11–79.32 wt% and calorific values of 25.45–28.61 MJ/kg. These properties assert the biochar and bio-oils among viable bioenergy sources.

Effectiveness of three Gabonese tree resin fractions combined with tebuconazole as wood preservative formulations

Wood treatments based on oleoresins from Aucoumea Klaineana, Canarium schweinfurthii and Dacryodes edulis have shown interesting anti-termites properties but poor resistance to fungi and leaching. Oleoresins were combined with tebuconazole to produce both antifungal and anti-termite wood preservatives formulations with an expected better fixation of chemicals mixtures in the wood. Beech and Scots pine wood block samples were impregnated by these different formulations and exposed to white and brown rot, respectively, as well as to European termite (Reticulitermes flavipes). The use of aqueous formulations of each oleoresin of combined to tebuconazole improved the wood resistance against termites and mainly brown rot. In addition, the best formulation was found by using the raw resin from Aucoumea Klaineana. These results are mainly due to the antifungal activity of tebuconazole. In addition, the presence of antioxidant chemicals in the wood resins inhibits the wood decay fungi growth and acts as enzyme and metabolism inhibitors disturbing the treated wood digestion process by termites. For the future, the promising protection obtained should be formulated to be resistant to leaching.

A question of rite—pearl millet consumption at Nok culture sites, Nigeria (second/first millennium BC)

The Nok culture in central Nigeria, dated 1500–1 cal bc, is known for its famous terracotta sculptures. We here present a study on > 11,000 botanical macro-remains from 50 sites, including 343 samples from Nok contexts and 22 samples dating between cal ad 100 and 400, after the end of the Nok culture. With 9,220 remains, pearl millet (Cenchrus americanus (L.) Morrone, syn. Pennisetum glaucum (L.) R.Br.) is dominant in the Nok samples, followed by cowpea (Vigna unguiculata (L.) Walp.), Canarium schweinfurthii Engl., Nauclea latifolia Sm. (syn. Sarcocephalus latifolius (Sm.) E.A.Bruce), wild fruit trees and wild Poaceae. The pearl millet remains consist exclusively of charred caryopses; chaff remains are completely absent. Because we studied all size fractions, including the small 0.5 mm fractions usually containing the involucres, bristles and husks, the absence of pearl millet chaff is real, excluding a methodological explanation, and distinguishes Nok from contemporary other West African sites. We propose that most excavated Nok sites were consumer sites where clean grain was brought in from outside and consumed in a ritual context connected with feasting. This is in line with the archaeological evidence from the larger excavated sites with stone-pot arrangements that are interpreted as ritual places related to mortuary practices. In addition to the known southward branches of pearl millet diffusion from the Sahara we propose a new, hitherto unknown branch directly from the central Sahara to the central Nigerian savannas.

Proximate and Detergent Fiber Fractions of de-Oiled African Olive (Canarium schweinfurthii Engl.) Residue: A Potential Animal Feedstuff

Proximate and detergent fiber composition of de-oiled African olive (Canarium schweinfurthii) residue were assessed using standard laboratory analytical procedures. Proximate composition showed 17.58 ± 0.21% crude protein, 4.13 ± 0.06% crude fat, 19.99 ± 0.89% crude fiber, 8.11 ± 0.33% ash and 50.20 ± 1.19% soluble carbohydrate. Detergent fiber components were 54.74±0.0745% NDF, 38.35 ± 0.59% ADF, 14.37 ± 0.68% ADL, 23.98 ± 0.10% cellulose and 16.40 ± 0.13% hemicellulose. Quantitative compositions of proximate and detergent fiber fractions were characteristic of roughage. De-oiled African olive pulp residue is relatively fair in protein and a good source of carbohydrate and digestible fiber for animal nutrition.

Chemical characterization and the effect of a polyherbal varnish coating on the preservation of Ayous wood (Triplochiton scleroxylon)

Research on the potential of natural substances to improve the durability and preservation of the physical properties of wood is nowadays an important concern. The objective of this work was to characterize and evaluate the effect of an ecological varnish formulated from Jatropha curcas seed oil and vegetable resins on the improvement of the resistance to biodeterioration agents (fungi and termites) and the preservation of the physical properties of Ayous wood. The varnish was formulated and characterized before being tested on Ayous wood. The properties of the formulated varnish (FV) were compared with those of a reference varnish (RV). The density of the FV was 0.99, while that of the RV was 1.6. FV showed better absorption (0.63) compared to 0.03 for RV, while the transmittance of RV was 94.5 % compared to 23.7 % for FV. The MALDI results showed that the FV contains oleic, linoleic, stearic, and palmitic acids probably from Jatropha curcas and unsaturated fatty acids from the resin of Aiélé (Canarium schweinfurthii, Engl.), such as 2-methyl-5-propan-2-yl cyclohexa-1,3-diene, 1-methyl-4-propan-2-yl cyclohexa-1,4-diene, (1 R,4 S,6 S)− 4,7,7-trimethylbicyclo [4.1.0] hept-2-ene. Catechin oligomers reacted with one molecule of 2-[(1 S)− 4-methyl cyclohex-3-en-1-yl]propan-2-ol were also detected, these derived from the reaction of the Vachellia nilotica tannin extract hardener with one of the main components of the Aiélé resin. Some resinite oligomers derived from the added rosin were also identified. All these significantly reduced the water absorption of the wood. The application of FV changed the color parameters of Ayous more than RV. RV showed a glossiness of 60GU (Glossines Unit), against 35GU for FV. According to ISO/CIE 11664–6 norm, Ayous wood was significantly protected against atmospheric aggression with ∆E * <4 after 4 months of exposure. All varnishes significantly protected the wood against all fungi tested with a mass loss of less than 5%. Finally, FV was more protective for Ayous wood against termites with a mass loss of 2 % against 40 % for RV. FV is an effective alternative for the preservation of Ayous wood and possibly other wood species.

Ethnobotanical Survey of Plants Used as Biopesticides by Indigenous People of Plateau State, Nigeria

The quest for sustainable health, environmental protection, and the conservation of beneficial organisms makes the use of biopesticides a desirable option. This research aimed to identify the botanicals used in the management of farm and household pests in Plateau State, Nigeria. A cross sectional study was carried out using semi-structured questionnaires and on-the-spot, face-to-face interviews. The main issues captured include the pests, the plants used to manage the pest, the parts used, the cultivation status, the availability, the effects on the pests, the indigenous formulation methods, and the modes of application. The quantitative data were analyzed using the Frequency of Citation (FC), Relative Frequency of Citation RFC (%), and Use Value (UV). A total of 45 plant species belonging to 42 genera, 20 orders, and 30 families were found to be useful in the management of 15 different pests. The FC, RFC (%), and UV values identified the most popularly used plants as Mesosphaerum suaveolens (L.) Kuntze, Gymnanthemum amygdalinum (Delile) Sch.Bip., Azadirachta indica A. Juss, Canarium schweinfurthii Engl., Euphorbiaunispina N.E.Br., and Erythrophloem africanum (Benth.) Harms. The plants that showed broad uses by the ethnic groups include Azadirachta indica A. Juss (7 uses), Erythrophloem africanum (Benth.) Harms, Khaya senegalensis (Desr.) A. Juss., and Gymnanthemum amygdalinum (Delile) Sch.Bip. The perception of the respondents indicated that most of the biopesticides are available, affordable, effective, eco-friendly, and safe. This survey provides a pathway for the formulation of stable biopesticides.

Contribution to vector control by essential oils of Aucoumea klaineana, Canarium schweinfurthii, Cymbopogon nardus, Dacryodes edulis and Eucalyptus citriodora from Gabon

Introduction: Aucoumea klaineana, Canarium schweinfurthii, Cymbopogon nardus, Dacryodes edulis, and Eucalyptus citriodora are of Gabonese origin, believed to have insecticidal activity. This study contributes to vector control by the insecticidal activities (larvicidal and ovicidal) of five essential oils from these plants against Anopheles gambiae, a major vector of malaria in Gabon. Methods: The essential oils were extracted by hydrodistillation. Larvicidal and ovicidal effects of essential oils were performed using different concentrations on third and fourth instar larvae and eggs of A. gambiae vectors. The effects of these oils were examined on the mortality rate of larvae and eggs. Results: The essential oils of A. klaineana, C. schweinfurthii, C. nardus, A. edulis, and E. citriodora showed greater activity against mosquito larvae (7.33 &lt; LC50 &lt; 107.14) compared to eggs (22.80 &lt; LC50 &lt; 64.63). D. edulis showed the highest activity against Anopheles gambiae eggs and larvae. Of all plants, essential oils from A. klaineana showed the lowest activity of A. gambiae eggs and larvae. Larvae were more sensitive than eggs. All essential oils were toxic to the various aquatic vectors of malaria. Conclusion: The study reveals the potential ovicidal efficacy and larvicidal activity of these plants against A. gambiae.

Thermal softening kinetics of African black olive fruit: Influence of temperature and water absorption on the thermal maceration dynamics and thermophysical properties

Softening of the pulp of African black olive fruit (Canarium schweinfurthii) is one of the unit operations in the maceration and de-pulping process of the pulp for consumption or to produce masticatories or oil. The softening process is temperature-sensitive, and hot water treatments are applied arbitrarily by local processors that might result in the hardening instead of maceration or softening of the fruits. This study, therefore, investigates the effect of hot water treatment on the softening and maceration kinetics of the fruits at different temperatures. To achieve this, two varieties of the fruits were selected and immersed in a water bath at temperatures of 30–60°C. Some of the parameters determined were the moisture absorption rate, hardness ratio, dimensional changes, thermal properties, and softening kinetics. The results showed that the softening curves and kinetics were directly affected by the temperature of the hot water. Hardening of the pulp occurred at a hot water temperature of 60°C for the long variety. In contrast, softening did not take place at 30°C for both varieties. Maceration occurred at 40–50°C for the long variety and 40–60°C for the short variety. The maximum maceration rate was at 50°C with an average softening rate of 0.161 N/hr for long variety and the least rate was 0.0565 N/hr for 40°C short variety. The activation energy was 47.46 kJ/mol for the short variety and 48.06 kJ/mol for the long variety. All the properties were presented as a function of the temperature or moisture content with good results. The obtained data will be helpful in the scaling up of the de-pulping process of the fruit by developing processing equipment for large-scale industrial processing and also prevents hardening that can result in losses for small-scale processors who soften and sell the fruits as snacks. Novelty impact statement Several studies abound on African black olive (Elemi) but none is available on the processing dynamics of softening the pulp for de-pulping the fruits to produce masticatories or oil. A good number of these research focused on physical properties, biochemical contents, proximate composition, and other in vivo assessments. Therefore, the present study highlights the softening kinetics of the fruit during the maceration process. It showed that (1) hardening of the pulp occurs at 60°C while 30°C cannot cause maceration; (2) The maceration rate follows a three-period pseudo first-order kinetics; (3) Quicker maceration can be achieved at 50°C soaking water temperature.

Combining air-layering and stem cutting techniques to optimize the production of quality planting materials for agroforestry tree species: a case study of Canarium schweinfurthii Engl. (Burseraceae)

ABSTRACT Using Canarium schweinfurthii as biological model, the present study evaluated the potential of combining air-layering and stem cutting techniques to optimize the production of agroforestry trees’ propagules. Three substrates and five concentrations of indole butyric acid (IBA) were tested for their effects on the rooting of air-layers. Stockplants were raised from air-layered propagules and used for stem cutting trial. Three levels of stockplant irradiance and five IBA concentrations were tested for their effects on the rooting of stem cuttings. Results showed that the combination of Sawdust substrate and 5 g/l IBA resulted in highest percentage of rooted layers (79.3 ± 7.6%) and highest number of roots per rooted layer (34.9 ± 0.7). Sawdust recorded the lowest layers’ mortality rate (6 ± 1.9%). Alive cuttings sprouted and rooted at 100%. The lowest mortality rates of cuttings (14 ± 4.8%) and the highest number of roots per rooted cutting (25.5 ± 0.1) were recorded with 10 g/l IBA × 50% ambient sunlight treatment combination. Using air-layered propagules for stockplant production could make it easy to achieve stockplant management practices like shading. Combining air-layering and stem cutting techniques enhanced the multiplication rate of propagules. This provides valuable insights for tree domestication practices worldwide.

Farmers’ Use of Indigenous Fruit Trees to Cope with Climate Variability in the Lake Victoria Basin Districts of Uganda

The escalating extreme weather conditions has forced rural farmers in Africa to rely disproportionately on Indigenous Fruit Trees (IFTs) to sustain their household food/nutrition security, employment and income generation. This paper analysed farmers’ use of IFTs to cope with climate variability in selected Lake Victoria Basin Districts of Uganda. Data were collected from farmers using questionnaires, key informant interviews and focus group discussions. From 13 most preferred IFTs, focus was on the most popular and highly ranked five: Garcinia buchananii, Vangueria apiculata, Canarium schweinfurthii, Tamarindus indica and Saba comorensis. Preferences for these IFTs were influenced by their uses for food, medicine, timber, compound shade provision and marketability. Age, sex, education, occupation, family size, land size, non-farming activities, period of stay on the same piece of land, and income level significantly (P≤0.05) influenced choice of the preferred IFTs. Majority of the respondents had IFTs planted on-farms, along the roads to provide various goods/services and in marginal lands unsuitable for farming to diversify agriculture as a strategy to cope with climate variability. Given that the uses of IFTs in the five LVB districts are associated with farmers’ efforts to cope with climate variability, the goal of any climate-adaptive farmer-based project should support sustainable use of IFTs, in the short-term and foster innovations such as on-farm planting of IFTs and other fast-growing tree species to meet household demands.