Cameroon Journal of Experimental Biology

Limestone rate affects potato bacterial wilt disease and Ralstonia solanacearum’s population in the soil in the Western Highlands zone of Cameroon

Melvis Bright Fomara — 2024-06-30

Potato bacterial wilt (BW) caused by Ralstonia solanacearum, is one of the major constraints to potato production in Cameroon. In order to reduce yield losses due to BW, this study aimed at investigating the effect of limestone on bacterial wilt disease, and on the R. solanacearum’s population in the soil. Potato tubers were grown in pots in a screen house of the University of Dschang, from February to May 2021. The experimental design was a split plot design made up of three replicates of two potato genotypes (Dosa and Jacob2005), 05 limestone rates (14.7 g, 29 g, 44,1 g, 58.8 g and 73.5 g per plant) and 2 controls (no liming without inoculation and no liming with pathogen inoculation). Plants were inoculated with 25 ml of bacterial suspension, containing 10⁸ CFU/ml. The bacterial population in the soil was assessed by counting colonies under microscope. Data were collected on BW incidence, bacterial population in the soil, soil pH, yield components and latent infection. The results showed that low BW incidence was associated with high rate of limestone in both genotypes. Limestone rate increased soil pH while reducing the pathogen population in the soil. The higher tuber weight/plant was obtained with limestone rate ≥58.8 g/plant. Liming enabled to avoid latent infection during storage. Thus, soil amendment with limestone at 58.8 g/plant can reduce R. solanacearum population in the soil and lower the impact of bacterial in the field as well as in the store in Dschang locality.

Peasants’ perceptions on the uses and exploitation of Tetracarpidium conophorum (Mull. Arg.) Hutch & Dalziel in Cameroon

Gaddielle Leslie Demgne Bemmo — 2024-06-30

Tetracarpidium conophorum (Mull. Arg.) Hutch & Dalziel, a vine of the Euphorbiaceae family, is one of the numerous useful plant species of the tropical forests, and is still exploited in the wild. The objective of this study was to understand peasants’ perceptions on the provisioning ecosystem services and the cultivation practice of T. conophorum in Cameroon, with a view to determining the suitability of this species for participatory domestication. The methodological approach consisted of ethnobotanical surveys carried out among 252 people spread across three agroecological zones of Cameroon, as well as field observations. The results showed that 100% of respondents know the species that they exploit for three categories of use, with a broad consensus for food use (Cs = 1), followed by energy use (Cs = 0, 92) and medicinal use (Cs = 0.17). The exploitation of the species provides income which is considered very important by 69% of respondents. The most common harvesting method in the study areas is fruit picking, which is practiced by 100% of respondents. A regressive trend in the dynamics of the T. conophorum population is perceived by 44% of respondents. According to 92% of respondents, cultivation habits of the species are almost non-existent due to the difficulty they experience in regenerating it (51% of respondents), the long duration of the vegetative growth phase (36%) and the uncertainty of fruits production (13%). All the interviewees (100%) expressed their desire to adopt the cultivation of the species if appropriate methods for propagating productive individuals were provided to them. This study shows that T. conophorum is conducive to participatory domestication in Cameroon.

Perceptions paysannes et stratégies d’adaptation aux changements climatiques des arboriculteurs de la Région des hautes terres de l’Ouest Cameroun

Danielle Morelle Chimi Tchouankap — 2024-06-30

The dependence of agriculture in tropical countries in general and in Cameroon in particular on rain-fed agriculture makes them more vulnerable to the effects of climate change and variability. In order to align their agricultural practices with frequent variations in climatic conditions, farmers according to agro-ecological zones have developed a set of climatic indicators allowing them to assess climatic disturbances and develop consequent adaptation strategies. This study aimed to analyze the evolution of climatic parameters from 1990 to 2020 in the Western Highlands region of Cameroon, to document the links between farmers' perceptions and the observed variations as well as adaptation strategies adopted. The climate data were collected at the meteorological station at Bamougoum airport and at the Institute of Agricultural Research for Development at Dschang. Ethnobotanical and sociological surveys were carried out among 414 arborists distributed in the divisions of Menoua, Haut-Nkam, Bamboutos and Noun. The resulting results show that climate parameters have varied over the past three decades with highest temperatures recorded during the years 2010 to 2013 (22.36°C and 22.5°C) and the years 2011, 2014 and 2018 were the ones that experienced major rainfall (164.61mm, 181.46mm, 191.16mm respectively). Regarding perception, 61.65% of arborists observed a drop in rainfall quantities and 73.79% of respondents observed an increase in temperature. These variations have a negative impact on the production and yields of rain-fed crops. As a result, arborists have opted for several adaptation strategies including the cultivation of fruit trees such as Persea americana, Dacryodes edulis, Mangifera indica, Citrus recticulata. It would be wise for decision-makers to better develop fruit growing as an adaptation strategy for rural populations in order to make them less vulnerable and effectively combat the effects of climate change.

Histopathology effects of Myxobolus pethericii Fomena, Lekeufack Folefack and Tang II, 2007 on Ctenopoma petherici Günther, 1864, in the Sangé River, Littoral Region, Cameroon

Beatrice Dambaya — 2024-06-30

Histological method, becoming common in diagnostic methodology, provides information on effect of parasite and help predicting therapeutic measures for aquatic animals. Ctenopoma petherici caught in Sangé River were examined for myxozoan infections. Cyst measurements were taken and prevalence was estimated. Formalin-fixed organs were dehydrated through a graded ethanol series and embedded in paraffin. Obtained sections were stained with hematoxylin and eosin. From examined fish, 93.33% harbored elongated, ovoid or spherical cysts measuring 70 - 660 µm long × 40 - 390 µm wide in one or more of the following organs: gills, heart, stomach, liver, gonads, eyes, skin, bones, muscles, intestine, mesentery, fins, opercula, esophagus, labyrinth organs, kidney, swimbladder, and gallbladder. Cysts were arranged anarchically on affected organs and their development was asynchronous. Histological observations revealed cysts implantation mostly in loose connective tissue on which they induce one or more of the following: hyperplasia, swelling, alteration and lack of adhesion between tissue layers. In some cases, cysts were responsible of mechanical compression and distortion of blood vessels surrounding affected tissue. In many cases, significant portion of affected organs was replaced by numerous and voluminous cysts leading to tissue destruction and reduction of organ’s functional area. Generally, few sign of fish immune response to the presence of cysts was observed. Histological examination of Ctenopoma petherici appears as an important tool for rapid diagnosis to ensure farming production. Therefore, monitoring M. pethericii in farmed fish using histological method would help in early and proper drug therapy and avoid it dissemination.

Acute and sub-chronic toxicity screening of aqueous and ethanolic extracts of Corynanthe pachyceras K. Schum (Rubiaceae), a Sub-Sahara African aphrodisiac plant

Aubrile Julie Ndomgang — 2024-06-30

Objective: This study investigated the acute and sub-chronic toxicities of the aqueous (AE) and ethanolic extract (EE) from Corynanthe pachyceras. Methods: Acute and sub-chronic toxicity tests were carried out following the 425 and 407 Organization for Economic Cooperation and Development (OECD) guidelines respectively. For the acute toxicity study, mice were randomly divided into groups treated with a single dose of distilled water (10 ml/kg) or the single reference dose (2000 mg/kg) of aqueous or ethanolic extract of C. pachyceras. Lethal dose 50 (LD50) was determined after 24h. Mice were individually checked for any toxicity sign and mortality over a 14-day period. For the sub-chronic toxicity study, young rats orally received repeated doses of each extract (50, 150 or 450 mg/kg) during 28 days. Body weight was taken every 2 days. After sacrifice, organ weights, hematological, biochemical and histopathological markers were measured. Results: The LD50 of C. pachyceras extracts was found to be greater than 2000 mg/kg in the acute toxicity study. In the sub-chronic toxicity test, males receiving the high dose (450 mg/kg) of both extracts significantly showed an increase (P<0.05-0.001) in immune cells. In rats treated with the low (50 mg/kg) and medium (150mg/kg) doses of the ethanolic extract of C. pachyceras, activity of ALAT and, concentrations of direct bilirubin, creatinine and total cholesterol were significantly increased (P<0.05-0.0001) when compared with control rats. C. pachyceras extracts did not alter the histology of the vital organs studied. Conclusion: C. pachyceras can be considered as non-toxic, but low doses are recommended to avoid possible chronic side effects.

Phenotypic features depict variability in Clarias jaensis wild populations in Cameroon

Juvenal Tonfack Djouatsa — 2024-06-30

This study was conducted to contribute to a better understanding of the phenotypic diversity of natural populations of Clarias jaensis in Cameroon, with the objective to harness the exploitation and conservation of this native catfish. A total of 269 native catfish (Clarias jaensis), including 139 males and 130 females, were sampled on 6 sites in Cameroon. One (1) phaneroptic observation, seventeen (17) biometric traits and four (4) meristic traits were evaluated. The main results showed that there are three colour patterns (brown, black and marbled) on the dorsal region and flanks in Clarias jaensis, with a predominance of brown (81.04%) and black (11.52%) patterns. The effect of sex on total weight (TW), snout length (SnL), prepelvic length (PPvL), total length (TL), standard length (SL), body depth (BD) and caudal peduncle depth (CPD) was significant (p<0.05). In general, biometric traits were significant (p<0.05) and positively correlated with total weight. The number of soft fin rays in dorsal fin (D) and anal fin rays (A) were negatively and weakly correlated with total weight (r=-0.02 and r=-0.04 respectively), while, the number of soft fin rays in pectoral fin was negatively and weakly correlated with total weight (r=0.13). The Principal Component Analysis (PCA) performed on all the biometric and meristic traits shows that the first two axes alone account for more than 50% of the total inertia. Hierarchical Ascending Classification (HAC) highlighted the existence of 3 morphotypes. The observed biodiversity suggests that the Clarias jaensis catfish is a natural genetic resource with the necessary variability to be exploited, though there is a need to develop population and habitats monitoring plan.

Cytogenotoxic and antihyperplastic effects of the aqueous extracts of Cymbopogon citratus (Poaceae) and Citrus medica (Rutaceae)

Harding Saah Namekong — 2024-06-30

Cymbopogon citratus and Citrus medica are commonly consumed in combination as an herbal tea to prevent or treat various conditions including cancers. This study evaluated the cytogenotoxic and antihyperplastic effects of aqueous extracts of C. citratus (AECC) and C. medica (AECM). Both extracts were chemically screened for the quantification of phytochemicals with genotoxic properties, and their antioxidant activities were evaluated in vitro. The cytogenotoxicity was evaluated on Allium cepa exposed to increasing concentrations (0.25, 0.5, and 1 mg/mL) of AECC and AECM and to mixtures of the two extracts [Mix 1 (AECC 0.25 + AECM 0.25), Mix 2 (AECC 0.5 + AECM 0.5) and Mix 3 (AECC 1 + AECM 1)] for 96 h. They were then examined macroscopically and microscopically for evaluation of mitotic index and chromosomal aberrations. The antihyperplastic effects of the two extracts were evaluated on the endometrium of ovariectomized rats. Endometrial hyperplasia was induced with tamoxifen (10 mg/kg; ip). Plant extracts were administrated orally for 37 days at the doses of 8, 40 and 200 mg/kg BW for AECC; 34, 170 and 850 mg/kg BW for AECM. The co-administration of the two extracts was carried out according to the following scheme: Mix 1: AECC 8 + AECM 34; Mix 2: AECC 40 + AECM 170; and Mix 3: AECC 200 + AECM 850. Animals were then sacrificed for biological analyses. Results showed that the contents of phenols, flavonoids, and tannins were lower in AECM than in AECC. AECC was also found to have greater antioxidant capacity than AECM. Both extracts induced chromosomal aberrations and reduced mitotic index (p < 0.001) in meristematic cells of A. cepa. These extracts also inhibited the hyperplastic effect of tamoxifen by reducing the uterine epithelium to a single cell layer (p < 0.001). This effect was associated with decreased serum estradiol levels, uterine oxidative stress and increased cytotoxicity. In conclusion, C. citratus and C. medica are endowed with genotoxic, mitodepressant, and antihyperplastic properties, justifying at least in part their use against cancers. The joint use of the two medicinal plants has proven to be more effective than their separate use.

Susceptibility of two cowpea varieties (Vigna unguiculata (L.) Walp.) to fungal infection in field in the western highlands (Dschang)

Abdou Nourou Nsangou Kone — 2024-06-30

Cowpea is an important food and socio-economic crop in West Africa. However, its yield is low due to biotic and abiotic constraints. The present work was carried out in the field and in the laboratory at the University of Dschang, Cameroon, with the general aim of identifying disease symptoms on cowpea (Vigna unguiculata L.) in the field during the growth stages. Two varieties were used (MTA-22 and TN5-78) in a completely randomized block design with three replications. The various symptoms of the diseases identified were described, their incidence and severity assessed, and a morphological characterization of the pathogens responsible for fungal diseases based on microscopic observation of fruiting bodies was carried out. At the end of this work, seven fungal diseases were identified and described. Four (4) fungal disease pathogens were clearly isolated and characterized: Fusarium oxysporum, Fusarium moniliforme, Cercospora canescens and Rhizoctonia solani These results will contribute to the development of a control program and the improvement of cowpea productivity with a view to combating malnutrition and reducing poverty in rural areas.

Gestion des risques de maladies des poissons d’élevage dans le Département de la Mvila, Sud-Cameroun

Georges Fonkwa — 2024-06-30

The aim of the present study is to contribute to the improvement of fish production through better practice of disease prevention measures. A biosecurity audit was carried out from March to May 2023 on 40 farms in the Mvila Division (2°48' 272" - 2°48' 993" N; 10°55' 066" - 10°56' 078" E), Southern Region of Cameroon. Semi-structured interviews and direct observation were used to collect data on socio-economic, zootechnical characteristics and biosecurity practice. The main results showed that, overall, the compliance rate (34.58%) and adoption rate (34.48%) of biosecurity measures were intermediate. Training received in fish farming and constraints associated with biosecurity practices, the production system, the production phase, culture facilities and disease diagnosis significantly affected the compliance rate. In addition, compliance with biosecurity measures significantly reduced fish mortality rates. A strong, positive and significant regression was established between the training received in fish farming and the biosecurity compliance rate, while constraints related to biosecurity practices were strongly, negatively and significantly associated with the compliance rate. The government must focus on training and capacity building of fish farmers in biosecurity.

Evaluation of the local knowledge in the production and consumption of commercial soy cheese skewers as a street food in the West Region of Cameroon

Elsa Nguepi Solefack — 2024-06-30

Soy cheese (tofu) skewer is a ready-to-eat meal, sold as street food in many cities of Cameroon and locally known as “soybean soya”. It is a rich source of plant proteins being produced locally for commercial purposes. This practice is considered as a job and source of revenue for individuals who partake in it and food for consumers. The aim of this study was to determine the current level of knowledge on the production conditions and the consumption habits of soy cheese skewers, commercialized in the streets of the West region of Cameroon. The survey consisted of using questionnaires to interview producers and consumers. Producers and consumers were randomly chosen to participate in this study. Results showed that about 81.63% (40) of producers were females, the majority had at least secondary level of education (57.14 %), the main age group 31 and 40 years (34.69%). The production conditions varied from one person to another, but the main steps were the same and included sorting, soaking, washing, draining, grinding, filtration, heating, coagulation, pressing, slicing, frying, stewing and packaging on skewers. Spices were mainly used for flavouring (100%) and the storage of unsold leftovers was done mostly at room temperature (65.31%) for less than 1 week (75.51%). Consumers of soy cheese skewer were of different age groups, gender, educational level, marital status and cultural background. Most often, it was purchased from the street (87.2%) at the price of 50 XCFA (87.66%). Many consumed it for its taste (75.32%) and very few for its nutritional value (8.44%). The texture appreciated by consumers and producers was tender (72.09%). The production and consumption of soy cheese skewer involves a series of steps whose application conditions vary from one producer to another, which may lead to variability in the products proposed to consumers.

Etude comparée de la qualité physico-chimique de l’eau, de la croissance et de la survie de Oreochromis niloticus en système aquaponique et en circuit fermé classique

Paul Zango — 2024-06-30

The aim of this trial was to compare the physicochemical characteristics of water, the survival rate and growth of Oreochromis niloticus under aquaponic and closed classical circuit. To achieve this aim, from March to April 2020, 230 adults of Oreochromis niloticus, with initial mean weight of 53.2 ± 1.03 g were randomly distributed in equal number into two concrete tanks corresponding to an Aquaponic System and Classical Closed system. The physicochemical characteristics were recorded every five days, and data for growth characteristics were collected after 15 days. After 45 days of rearing, the high of Capsicum chinense were measured and age of flowering plants noted. the mains results were as follows: Dissolved Oxygen values (9.0 ± 1.7 mg / l), ammoniac nitrogen (0.3 ± 0.05 mg / l) and nitrates (3.31 ± 0.7 mg / l) were higher in a closed classical circuit as compared to the aquaponic system, the final mean weight (118.3 ± 25.4 g), the mean weight gain (65.1 ± 28.3 g), the condition factor K (K = 3.8 ± 1.6) and survival rate (100% ) were higher in aquaponic system. The survival rate (91.0 ± 0.2 %) and the final high of Capsicum chinense (52.03 ± 0.5 cm) were higher and the flowering age (30,0 ± 2,0 j) was very short in aquaponic system. The aquaponic system offers a better environment for life and growth to Oreochromis niloticus and Capsicum chinense as compared to the classical closed circuit.

Effect of coating based on orange epicarp extract on the ripening of avocado (Percea americana L.)

Emmanuel Mbatchamen — 2024-06-30

The shelf life of avocados during the post-harvest period is very limited due to
rapid senescence. In order extend the shelf life of the avocados, the effects of coating based on orange epicarp extracts were tested on the physical and physiological parameters of the ripening process. Avocados were coated with different concentrations of orange epicarp extracts, including 0.066 Kg.l¹, 0.133 Kg.l¹, 0.2 Kg.l¹ and 0.26 Kg.l¹. Uncoated fruits were considered as control. Twelve parameters including loss of firmness, physiological loss of mass, water content in the pulp, soluble solids content, pH, protein content, pigment content in skin and pulp as well as time to senescence were measured during the ripening process. Results showed that, 0.133 Kg.l¹ was found to be the most effective extending the time to senescence of avocado by slowing down the loss of firmness, physiological mass loss, chlorophyll degradation and protein synthesis as compared to the other concentrations of orange epicarp extracts and the control. Orange epicarp at a concentration of 0.133 Kg.l¹helped to extend the shelf life of avocados.