Southern Part Of Cameroon Research Articles

Re-description and bio-ecology of two species of the genus Thibron (Rehn, 1938) (Orthoptera: Tetrigidae) in the Southern part of Cameroon

Taxonomy and bio-ecology of Tetrigidae in Cameroon remain poorly studied. This study reports for the first time the presence of Thibron cf. tectatus Günther, 1979 in Cameroon and provides morphological and bio-ecological characteristics of Thibron illepidus (Karsh, 1893) and T. cf. tectatus. The specimens studied were collected between February 2016 and February 2018 in three regions of Cameroon. In each region, species were collected monthly using sweep-nets and pitfalls in four vegetation types. Some morphological characters formerly omitted in previous descriptions were considered in this study. In addition to the characters already known, T. illepidus differs from other species of the same genus in terms of length of body and interocular space, posterior thigh width, median femur length and width and finally the length of the three tarsomeres of posterior tarsus only in T. illepidus. In addition, for T. cf. tectatus, the length of the head, fastigium of vertex, eyes are longer than in T. illepidus. The later was more abundant in the Centre region (79%), less abundant in the Southwest region (18%) and rare in the West (3%). Meanwhile, Thibron cf. tectatus is rare in the Centre region (4%). Pitfalls (92%) were more effective than sweep-nets (8%) in capturing T. illepidus. Results obtained could contribute to improve the knowledge of the taxonomy of both species in Cameroon.

Distribution of acetylcholinesterase (Ace-1R) target-site G119S mutation and resistance to carbamates and organophosphates in Anopheles gambiae sensu lato populations from Cameroon

BackgroundCameroon is considering the implementation of indoor residual spraying (IRS) as a complementary measure to control malaria in the context of high pyrethroid resistance in major malaria vectors. Non-pyrethroid insecticide classes such as organophosphates and carbamates may be utilized in IRS due to widespread pyrethroid resistance. However, the success of this strategy depends on good knowledge of the resistance status of malaria vectors to carbamates and organophosphates. Here, we assessed the susceptibility profile of Anopheles gambiae sensu lato with respect to carbamates and organophosphate and the distribution of the molecular mechanism underlying resistance to these insecticides.MethodsAnopheles gambiae s.l. mosquitoes were collected from nine settings across the country and bio-assayed with bendiocarb, propoxur and pirimiphos-methyl. The Ace-1 target-site G119S mutation was genotyped using a TaqMan assay. To investigate the polymorphism in the Ace-1 gene, a region of 924 base pairs in a sequence of the gene was amplified from both live and dead females of An. gambiae exposed to bendiocarb.ResultsPirimiphos-methyl induced full mortality in An. gambiae s.l. from all study sites, whereas for carbamates, resistance was observed in four localities, with the lowest mortality rate recorded in Mangoum (17.78 ± 5.02% for bendiocarb and 18.61 ± 3.86% for propoxur) in the southern part of Cameroon. Anopheles coluzzii was found to be the predominant species in the northern tropical part of the country where it is sympatric with Anopheles arabiensis. In the localities situated in southern equatorial regions, this species was predominant in urban settings, while An. gambiae was the most abundant species in rural areas. The G119S Ace-1 target-site mutation was detected only in An. gambiae and only in the sites located in southern Cameroon. Phylogenetic analyses showed a clustering according to the phenotype.ConclusionThe occurrence of the Ace-1 target-site substitution G119S in An. gambiae s.l. populations highlights the challenge associated with the impending deployment of IRS in Cameroon using carbamates or organophosphates. It is therefore important to think about a resistance management plan including the use of other insecticide classes such as neonicotinoids or pyrrole to guarantee the implementation of IRS in Cameroon.Graphical

Spatial distribution of rattan and indigenous perspectives vis-à-vis the growth rate of economically important rattan species in Cameroon: Sustainability and policy implications

Rattan is an important Non-Timber Forest Product (NTFP) with huge potential to boost socio-economic development in indigenous communities of Cameroon in particular and the entire country in general. Rattan is mainly harvested from the wild, with no involvement of stakeholders in renewing the resource, leading to resource scarcity. Insufficient knowledge on rattan distribution and growth rate in Cameroon jeopardizes the sustainable management of its resource base. It was in this context that this study was initiated to (i) determine economically important rattan species and their distribution; (ii) identify their habitats and conservation status; (iii) examine harvester's perceptions/observations on annual growth rate and age of maturity. Findings revealed that Eremospatha macrocarpa exists in all AEZs, Calamus deerratus was found in AEZ 2 & 5, Laccosperma secundiflorum, L. Robustum, was found in AEZ 3, 4, and 5 and Eremospatha wendlandiana was found only in AEZ4. They grow in diverse habitat/environments with some habitats/environments specifically suitable for some rattan species. The current conservation status of commercial rattan species identified shows Least Concern (LC), but resource scarcity is high. Most harvesters observed that rattan takes either 2–3 years (51%) or 4–5 years (35%) to attain maturity. The harvesters' observation on the annual growth rate of economic rattan species varied in relation to the species and AEZs. However, overall 25% and 23% of the respondents observed a growth rate of 2–3 m and 3–4 m respectively. Kruskal-Wallis test shows a significant variation in harvesters' observations in the different AEZs for all growth and maturity parameters of different rattan species (p < 0.05) except for the number of years it takes for rattan to attain maturity (p > 0.05)”. All five economically important rattan species are widely distributed in the Southern part of Cameroon. The availability of E. macrocarpa in all zones indicates its great adaptation to different climatic and ecological conditions. Increasing the rattan resource base will involve its domestication, especially in the southern part of Cameroon where all rattan species thrive. The findings of this study are important for policymakers and development planners who seek to ensure the sustainable harvesting and management of the rattan resource base in Cameroon.

Description of Heteracris lecoqi Yetchom-Fondjo &amp;amp; Kekeunou sp. nov. and Heteracris hannai Wandji &amp;amp; Kekeunou sp. nov. and redescription of Heteracris guineensis (Krauss, 1890) (Orthoptera: Acrididae) with comments on its ecology in the Southern part of Cameroon

The specimens studied were collected with sweep net and pitfall in the forests, agro-forests, herbaceous fallows, and crop fields of 14 localities in the southern part of Cameroon, from August 2015 to February 2018. The results show that Heteracris hannai sp. nov. and Heteracris lecoqi sp. nov. differ from previously known species of the same genus by the pattern of coloration and the details or shape of the phallic complex. H. lecoqi sp. nov. is characterized by light brownish body; male cercus with flattened, downcurved and obtuse apex; lophus strongly curved; interlophal space with V shape; apodeme of cingulum bow, convergent, with V-shape; valve of cingulum in lateral view longer than apical valve of penis; ramus in ventral view joined. H. hannai sp. nov. is distinct to other species by brown to grey body; male cercus with apex rounded, curved inside; lophus curved; interlophal space with U-shape; apodeme of cingulum thick, slightly parallel, with U shape; valve of cingulum in lateral view hardly longer than apical valve of penis; ramus in ventral view opened. The characteristics of H. guineensis are closer to H. hannai sp. nov. than to H. lecoqi sp. nov. H. lecoqi sp. nov. was collected only in the fallows while H. hannai sp. nov. was collected in the forests, agro-forests, fallows, and crop fields. Compared to H. guineensis, both new species are scarce in the natural vegetation and their distribution area is limited to two and four localities respectively for H. lecoqi sp. nov. and H. hannai sp. nov. All these three grasshopper’s species were recorded as accidental species in all types of vegetation.

Nationwide profiling of insecticide resistance in Aedes albopictus (Diptera: Culicidae) in Cameroon.

The Asian mosquito, Aedes albopictus (Skuse), is an invasive mosquito which has become one of the most important vectors of dengue, Zika, and chikungunya viruses worldwide. This species was reported for the first time in Cameroon in early 2000s and became the dominant Aedes species in the urban areas in the southern part of Cameroon but remain poorly characterized. Here, we assessed the susceptibility profile of A. albopictus collected throughout Cameroon and investigated the potential resistance mechanisms involved. Immature stages of A. albopictus were collected between March and July 2017 in 15 locations across Cameroon and reared until G1/G2 generation. Larval, adult bioassays, and synergists [piperonyl butoxide (PBO) and diethyl maleate (DEM)] assays were carried out according to WHO recommendations. F1534C mutation was genotyped in field collected adults (Go) using allele specific PCR. All tested populations were susceptible to both larvicides, temephos and Bacillus thuringiensis israelensis (Bti), after larval bioassays. Adult bioassays revealed a high level of resistance of A. albopictus to 4% DDT with mortality rates ranging from 12.42% in Bafang to 75.04% in Kumba. The resistance was reported also in 0.05% deltamethrin, 0.25% permethrin, and 0.1% propoxur in some locations. A loss of susceptibility to 0.1% bendiocarb was found in one of three populations analysed. A full susceptibility to 1% fenitrothion were observed across the country. A full recovery or partial of susceptibility was observed in A. albopictus when pre-exposed to PBO or DEM and then to DDT and permethrin, respectively. The F1534C kdr mutation was not detected in A. albopictus. This study showed that the susceptibility profile of A. albopictus to insecticide vary according to the sampling location and insecticides used. These findings are useful to planning vector control program against arbovirus vectors in Cameroon and can be used as baseline data for further researches.

Ethnic heterogeneity of knowledge onZonocerus variegatus and reasons for consumption and non-consumption in the southern part of Cameroon

With the growth of the human population, non-timber forest products of animal origin, such as grasshoppers, could be an approach to the solution of food shortage. The variegated grasshopper is an edible insect and an agricultural pest in several African countries. This study aimed to evaluate the knowledge, the level and reasons of consumption and non-consumption of this grasshopper in different ethnic groups in the south part of Cameroon. An individual structured survey, conducted from January to February 2018, among ten ethnic groups revealed that 99% of the participants know the variegated grasshopper. It has 22 local names, withmba’assana as the most common name. This grasshopper is mainly used for consumption (93.7%) and the level of consumption is higher among the Mbamois, Bulu, Ntumu, Pygmies and Maka people. It is used as medicine (3.9%), to treat splenomegaly, umbilical hernia, and to prevent rheumatism and benign prostatic hypertrophy. It is also used in traditional rites (0.6%) (Eton) and as a source of income (0.6%) (Ewondo). People consume the variegated grasshopper mainly because of its good taste and high nutritional value (73.24%). The adult is the stage mostly consumed when fried. The Bassa also consume the larvae (6%). Those who refuse the insect mostly talk of its bad odour and that its consumption can lead to the appearance of various pathologies (3.6%) such as cramps, stomach pain, paralysis, allergy, diarrhoea, nerve pain, abdominal pain, poisoning, vomiting and death. The repellent gland could be involved in the toxicity related to the consumption of this grasshopper. For the Bulu people, poor cooking is a risk factor. Further studies are needed on the potential risks of the variegated grasshopper before it could be recommended for general human consumption.

Assessing Shifting Cultivation Trajectories in the Southern Part of Cameroon

Good understand of changes in shifting cultivation and factors involved is a way forward in finding appropriate respond to preserve forested landscapes. A study was conducted with the aim of analyzing different pathways that could be taken in shifting cultivation trajectories. A total of 470 households were randomly sampled in the three study sites of the southern part in Cameroon. Data were collected using household survey, focus group discussion, interview of key informants and remote sensing based analysis of land cover. We found that shifting cultivation could migrate from traditional to a relatively modern form. Modern form is characterized by the evolution of objective from consumption to commercialization, a very short fallow, improvement of technique, and introduction of new market crops and diversification of crops produced. It is affected by population density, availability of forest land and accessibly (road and transport). In the site where traditional form is observed, 88 % of respondents revealed that there is still forest land belonging to nobody where they can create new farm. Therefore, a good management of land will constraint shifting cultivators to shift to modern agricultural technique. Moreover, it is advisable to develop policy measures to promote the progressive change of this old practice towards the adoption of appropriate agricultural techniques in the context of preservation of forested landscape.

Update on the distribution of Mansonella perstans in the southern part of Cameroon: influence of ecological factors and mass drug administration with ivermectin

BackgroundMansonellosis remains one of the most neglected of tropical diseases and its current distribution in the entire forest block of southern Cameroon is unknown. In order to address this issue, we have surveyed the distribution of Mansonella perstans in different bioecological zones and in addition, elucidated the influence of multiple rounds of ivermectin (IVM) based mass drug administration (MDA).MethodsA mixed design was used. Between 2000 and 2014, both cross-sectional and longitudinal surveys were carried out in 137 communities selected from 12 health districts belonging to five main bioecological zones of the southern part of Cameroon. The zones comprised of grassland savanna (GS), mosaic forest savanna (MFS), forested savanna (FS), deciduous equatorial rainforest (DERF) and the dense humid equatorial rainforest (DHERF). The survey was carried out in some areas with no treatment history as well as those currently under IVM MDA. Individuals within the participatory communities were screened for the presence of M. perstans microfilariae (mf) in peripheral blood by the calibrated thick film method to determine both prevalence and geometric mean intensities at the community level.ResultsApart from sporadic cases in savanna areas, distribution of M. perstans was strongly linked to the equatorial rainforest zones. Before CDTI, the highest mean prevalence (70.0 %) and intensity (17,382.2 mf/ml) were obtained in communities in Mamfes’ DHERF areas followed by communities in the DHERF zone of Lolodorf (53.8 % and 7,814.8 mf/ml, respectively). A longitudinal survey in Mamfe further showed that M. perstans infections had reduced by 34.5 % in DERF (P < 0.001) but not DHERF zones after ten years of IVM MDA. Further data from the cross-sectional study revealed that there was a decrease in prevalence in DHERF zones only after ten years of MDA. In DERF zones however, the infection was relatively lower after four years of MDA.ConclusionsThe distribution of M. perstans in the southern part of Cameroon varies with bioecological zones and IVM MDA history. The zones with high prevalence and intensities lie in forested areas while those with low endemicity are in the savanna areas. MDA with ivermectin induced significant reduction in the endemicity of mansonellosis in the decidious equatorial rainforest. In contrast, the prevalence and intensity remained relatively high and stable in the dense humid equatorial rainforest zones even after a decade of mass drug administration with ivermectin. Since it is known that M. perstans down-regulates host's immune system, the findings from this work would be useful in designing studies to understand the impact of M. perstans on host immune response to vaccination and co-infection with other pathogens such as Mycobacterium spp. and Plasmodium spp. in areas of contrasting endemicities.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1595-1) contains supplementary material, which is available to authorized users.

Patterns of species richness and diversity of insects associated with cucurbit fruits in the southern part of Cameroon.

Patterns of species diversity and community structure of insects associated with fruits of domesticated cucurbits were investigated from January 2009 to 2011 in three localities from two agroecological zones in the southern part of Cameroon. Rarefaction curves combined with nonparametric estimators of species richness were used to extrapolate species richness beyond our own data. Sampling efforts of over 92% were reached in each of the three study localities. Data collected revealed a total of 66 insect morphospecies belonging to 37 families and five orders, identified from a set of 57,510 insects. The orders Diptera (especially Tephritidae and Lonchaeidae) and Hymenoptera (mainly Braconidae and Eulophidae) were the most important, in terms of both abundance and species richness on the one hand, and effects on agronomic performance on the other. Values for both the species diversity (Shannon and Simpson) and the species richness indices (Margalef and Berger–Parker) calculated showed that the insect communities were species-rich but dominated, all to a similar extent, by five main species (including four fruit fly species and one parasitoid). Species abundance distributions in these communities ranged from the Zipf–Mandelbrot to Mandelbrot models. The communities are structured as tritrophic networks, including cucurbit fruits, fruit-feeding species (fruit flies) and carnivorous species (parasitoids). Within the guild of the parasitoids, about 30% of species, despite their low abundance, may potentially be of use in biological control of important pests. Our field data contribute in important ways to basic knowledge of biodiversity patterns in agrosystems and constitute baseline data for the planned implementation of biological control in Integrated Pest Management.

Mapping of schistosomiasis and soil-transmitted helminthiasis in the regions of Littoral, North-West, South and South-West Cameroon and recommendations for treatment

BackgroundThe previous nationwide mapping of schistosomiasis and soil-transmitted helminthiasis (STH) in Cameroon was conducted 25 years ago. Based on its results, mass drug administration (MDA) of praziquantel was limited to the three northern regions and few health districts in the southern part of Cameroon. In 2010, we started the process of updating the disease distribution in order to improve the control strategies. Three of the ten regions of Cameroon were mapped in 2010 and the data were published. In 2011, surveys were conducted in four additional regions, i.e. Littoral, North-West, South and South-West.MethodsParasitological surveys were conducted in March 2011 in selected schools in all 65 health districts of the four targeted regions, using appropriate research methodologies, i.e. Kato-Katz and urine filtration.ResultsThe results showed significant variation of schistosomiasis and STH prevalence between schools, villages, districts and regions. Schistosoma haematobium was the most prevalent schistosome species, with an overall prevalence of 3.2%, followed by S. mansoni (3%) and S. guineensis (1.2%). The overall prevalence of schistosomiasis across the four regions was 7.4% (95% CI: 6.7-8.3%). The prevalence for Ascaris lumbricoides was 19.5% (95% CI: 18.3-20.7%), Trichuris trichiura 18.9% (95% CI: 17.7-20.1%) and hookworms 7.6% (95% CI: 6.8-8.4%), with an overall STH prevalence of 32.5% (95% CI: 31.1-34.0%) across the four regions. STH was more prevalent in the South region (52.8%; 95% CI: 48.0-57.3%), followed by the South-West (46.2%; 95% CI: 43.2-49.3%), the North-West (35.9%; 95% CI: 33.1-38.7%) and the Littoral (13.0%; 95% CI: 11.3-14.9%) regions.ConclusionsIn comparison to previous data in 1985–87, the results showed an increase of schistosomiasis transmission in several health districts, whereas there was a significant decline of STH infections. Based on the prevalence data, the continuation of annual or bi-annual MDA for STH is recommended, as well as an extension of praziquantel in identified moderate and high risk communities for schistosomiasis.

Water-table Control Using Ordinary Kriging in the Southern Part of Cameroon

Water-table Control Using Ordinary Kriging in the Southern Part of Cameroon

Mapping of Schistosomiasis and Soil-Transmitted Helminthiasis in the Regions of Centre, East and West Cameroon

BackgroundSchistosomiasis and soil-transmitted helminthiasis (STH) are widely distributed in Cameroon. Although mass drug administration (MDA) of mebendazole is implemented nationwide, treatment with praziquantel was so far limited to the three northern regions and few health districts in the southern part of Cameroon, based on previous mapping conducted 25 years ago. To update the disease distribution map and determine where treatment with praziquantel should be extended, mapping surveys were conducted in three of the seven southern regions of Cameroon, i.e. Centre, East and West.MethodologyParasitological surveys were conducted in April–May 2010 in selected schools in all 63 health districts of the three targeted regions, using appropriate research methodologies, i.e. Kato-Katz and urine filtration.Principal FindingsThe results showed significant variation of schistosomiasis and STH prevalence between schools, villages, districts and regions. Schistosoma mansoni was the most prevalent schistosome species, with an overall prevalence of 5.53%, followed by S. haematobium (1.72%) and S. guineensis (0.14%). The overall prevalence of schistosomiasis across the three regions was 7.31% (95% CI: 6.86–7.77%). The prevalence for Ascaris lumbricoides was 11.48 (95% CI: 10.93–12.04%), Trichuris trichiura 18.22% (95% CI: 17.56–18.90%) and hookworms 1.55% (95% CI: 1.35–1.78%), with an overall STH prevalence of 24.10% (95% CI: 23.36–24.85%) across the three regions. STH was more prevalent in the East region (46.57%; 95% CI: 44.41–48.75%) in comparison to the Centre (25.12; 95% CI: 24.10–26.17%) and West (10.49%; 95% CI: 9.57–11.51%) regions.Conclusions/SignificanceIn comparison to previous data, the results showed an increase of schistosomiasis transmission in several health districts, whereas there was a significant decline of STH infections. Based on the prevalence data, the continuation of annual or bi-annual MDA for STH is recommended, as well as an extension of praziquantel in identified moderate and high risk communities for schistosomiasis.

CHEMICAL COMPOSITION OF OIL FROM COULA EDULIS (Bail.) NUTS

ABSTRACT Coula edulis (Bail.) nuts are generally used as food components in the littoral and southern part of Cameroon. The physicochemical characteristics, the fatty acids and the triacylglycerols (TGs) of Coula edulis (Bail.) nut oil from two different agroclimatical zones of Cameroon were studied. The oil content varied according to the zone (33.50 – 36.65%). The iodine value (90 – 95), saponification value (180 – 185) and the nitrogen (2.16 – 2.40%), and ash (2.5 to 2.7%) contents were similar for the two types of nuts studied. The main fatty acid of the oil was oleic acid (95.5 – 97.4%), as determined by capillary gas chromatographic analysis. The triacylglycerol profile obtained by reversed phase liquid

Efficacy of insecticide impregnated bed-nets to control malaria in a rural forested area in southern Cameroon.

Due to current spreading of chemoresistant strains of Plasmodium falciparum malaria control must incorporate vector control programmes. Due to well known constraints house sprayings cannot be performed as before. Personal protection can be developed and a large scale use of insecticide treated bed-nets appeared to be very useful to reduce man-vector contact in Asia, South America and West and East Africa. No trial has been done in forest Central Africa where transmission is permanent. We performed such a trial in the southern part of Cameroon (using deltamethrin, at 25 mg/m2) and obtained similar data to those observed in The Gambia, Burkina Faso and Tanzania with a noteworthy reduction of both transmission and high parasitaemia of P. falciparum (respectively 78% and 75%) meaning a drop of malaria morbidity.