Cowpea, Vigna unguiculata (L.) Walp. is an economically important seed legume that helps combat food and nutrition insecurity in the Sahel, particularly Niger. However, its yield remains low due to insect pest attacks...Cowpea, Vigna unguiculata (L.) Walp. is an economically important seed legume that helps combat food and nutrition insecurity in the Sahel, particularly Niger. However, its yield remains low due to insect pest attacks. This study was conducted at a station and in seven villages in the Maradi and Tahoua regions. It aimed to test the effectiveness of neem seed biopesticides [Azadirachta indica A. Juss] and sanitized human urine for integrated insect pest management. The cowpea variety UAM09 1055-6 was used for the experiments. The experimental trial was a Fisher block design consisting of five treatments: neem oil, neem seed extract (NSE), hygienized human urine (HHU), chemical pesticide, and a control, replicated five times at the station and twice in farmers’ environments. The study shows that Megalurothrips sjostedti Trybom, Clavigralla tomentosicollis Stål and Maruca vitrata Fabricius are the main insect pests. Plots treated with synthetic pesticides were the least infested by C. tomentosicollis. They were followed by neem seed extract and HHU treatments, which recorded an infestation level of 2.44 and 20.5 times lower than controls at the station and in farming environments. The density of thrips was 1.06 to 32.6 times lower in treated plots compared to controls. The proportion of pods damaged by M. vitrata was 1.95, 2.55, and 2.77 times lower in plots treated with HHU, NSE, and synthetic pesticide, respectively, compared to controls. Grain yields were 1.80 and 2.62 times higher in UHH and NSE treatments compared to control plots, both at the station and in farmers’ environments. A yield increase of 44.58% and 61.92% was noted for these treatments at the station and in farmers’ environments, respectively. These results may promote the dissemination of NSE and HHU biopesticide technologies in rural areas as an alternative method for integrated pest management of cowpeas.展开更多
Cultivating traditional upland rice cultivars on nutrient depleted soil causes poor and low yield. Little attention is paid to performance of inter-specific NERICA cultivars grown on nutrient deficient soil augmented ...Cultivating traditional upland rice cultivars on nutrient depleted soil causes poor and low yield. Little attention is paid to performance of inter-specific NERICA cultivars grown on nutrient deficient soil augmented with different types of compost. Therefore, field trials were conducted during 2010 and 2011 planting seasons in Ibadan to evaluate growth, dry matter, nutrient uptake efficiency and grain yield of upland rice grown on nutrient deficient soil augmented with different types of compost. There were nine treatments comprising of three upland rice cultivars: NERICA I, NERICA II and Ofada, two compost types applied at the rate of 8 t·ha-1: poultry dropping + maize stover (PDMC) and cattle dung + maize stover (CDMC) and control. The treatments were laid out in randomized complete block design and replicated three times. CDMC enhanced growth, nutrient use efficiency, dry matter and grain yield of upland rice cultivars. Performance of Ofada was better than NERICA cultivars. N (24.55 g), P (12.45 g) and K (35.41 g) uptake concentration and grain yield (5.45 t/ha) were highest in Ofada plots augmented with CDMC. Residual effect of compost on growth, yield and nutrient uptake efficiency of upland rice on nutrient deficient soil was marginal.展开更多
In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing...In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at:(1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures;(2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated(n = 3) 5 and10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly(p \ 0.05) greater than that from Euclea.racemosa. Average daily fuelwood consumption per person was(0.63 ± 0.2) kg day^(-1). This means that the total biomass(27.5 Mg year^(-1)) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents(95%) confirmed that they travel more than10 km day^(-1) to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.展开更多
Whole grain cereals are important dietary sources for management of metabolic diseases due to the bioactive components they contain.Hence,this study investigated enzymes(pancreatic lipase,-amylase,-glucosidase,xanthin...Whole grain cereals are important dietary sources for management of metabolic diseases due to the bioactive components they contain.Hence,this study investigated enzymes(pancreatic lipase,-amylase,-glucosidase,xanthine oxidase and angiotensin 1-converting enzyme)inhibitory property,antioxidant activity and phenolics profile of raw and roasted red sorghum(Sorghum bicolor)grains in vitro.Extracts of flours of raw and roasted(150◦C and 180◦C,for 20 min)grains were assayed for enzymes inhibitory and antioxidant activities using spectrophotometric methods;while their phenolic constituents were characterized using HPLC-DAD.The raw grains exhibited strong enzymes inhibitory and antioxidant activities,and contained phenolic acids(gallic,chlorogenic,caffeic,ellagic and p-coumaric acids)and flavonoids(quercetin,luteolin and apigenin).However,whereas the enzymes inhibitory activity and levels of the phenolic compounds in the grains decreased significantly(p<0.05)with increasing roasting temperature,the antioxidant activity increased.Hence,roasting at high temperature may not be recommended for the optimum retention of the enzymes inhibitory property and phenolic compounds of red sorghum grains.展开更多
During the last decade, Jatropha curcas L. (J. curcas) has gained much attention worldwide as biofuel crop. Although its cultivation is promoted in the Sahel, there is a surprising lack of data on its water use regula...During the last decade, Jatropha curcas L. (J. curcas) has gained much attention worldwide as biofuel crop. Although its cultivation is promoted in the Sahel, there is a surprising lack of data on its water use regulation and growth in this region. Here, we investigated, in semi-controlled conditions, leaf transpiration and growth of six accessions of J. curcas at seedling stage under natural changing in vapour pressure deficit (VPD) and progressive soil drying in Senegal. The experimental layout was a randomized complete bloc design and after 3 months of growth arranged to a split-plot at the implementation of water stress to facilitate irrigation. Under well water condition, there was no significant difference between accessions for leave transpiration that was positively correlated to VPD with high values recorded between 13 h and 14 h pm. Accessions of J. curcas used in this study showed closed thresholds at which transpiration declined except accession from Ndawene that threshold was lower (0.30). There is no significant difference between accessions for growth during the experimentation period. In 3 months, we recorded 23.57 g for the aboveground dry biomass and seedlings had about 14 leaves and 24.3 cm height. Positive linear correlation was recorded between aboveground biomass and root dry weight (p J. curcas might need complement irrigation for a better growth of seedlings especially during the dry season.展开更多
Understanding the nature and extent of association between yield and yield related traits is the prerequisite study for any underutilized crop improvements of sustainable genetic enhancement. However, there is a lack ...Understanding the nature and extent of association between yield and yield related traits is the prerequisite study for any underutilized crop improvements of sustainable genetic enhancement. However, there is a lack of sufficient information on seed yield and related trait correlation and path coefficient analysis of cowpea in Ethiopia. To fill the existing knowledge gap, the present study was conducted to determine the nature and extent of phenotypic and genotypic correlation and path coefficient analysis among 18 quantitative traits. A total of 324 cowpea landraces were tested in 18 × 18 simple lattice design at Melkassa Agricultural Research Center and Miesso sub center during 2016 cropping season. The magnitude of genotypic correlations was higher than phenotypic correlations in most traits at both locations;this implies that the traits under consideration were genetically controlled. Seed yield was positively and highly significantly correlated with most of the traits at phenotypic and genotypic levels, indicating the presence of strong inherited association between seed yield and the other 17 traits. Almost all traits genotypic direct and indirect effects were higher than the phenotypic direct and indirect effects;this indicated that the other traits had a strong genetically inherited relationship with seed yield. Genotypic path coefficient analysis revealed that days to flowering, biomass and harvest index at Miesso, and seed thickness, plant height, days to maturity and biomass at Melkassa had relatively high positive direct effect on seed yield. However, seed width and hundred seed weight had exerted negative direct effect on seed yield at each location. Phenotypic path coefficient analysis showed that biomass and harvest index had exerted high positive direct effect on seed yield at both locations. From these results it can be concluded from this study that seed yield in cowpea can be improved by focusing on traits pod length, seed length, seed thickness, seed width, biomass and harvest index at both locations. The information obtained from this study can be used for genetic enhancement of cowpea thereby developing high yielding varieties.展开更多
The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was le...The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung （D）, nitrogen （N） and phosphorus （P） in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol.展开更多
The production of maize is constrained by parasitic weeds, particularly Striga. A study was carried out to document farmers＇ knowledge, attitude and practices on Striga control among smallholder farmers across three ...The production of maize is constrained by parasitic weeds, particularly Striga. A study was carried out to document farmers＇ knowledge, attitude and practices on Striga control among smallholder farmers across three districts： Kisumu West, Busia and Teso South of Western Kenya. A multistage sampling technique was used to select the locations and farmers to be interviewed. A semi structured, open and closed ended questionnaire was administered leading to field experiment. Besides village meetings （39.2%）, farmers got informed on farming methods under Striga weed farms and its control technologies through neighbours （2.5%）, workshops and trainings （5.0%）, field schools （3.7%）, media （7.5%） and extension agents （10.8%）. The attitudes of farmers towards Striga control varied but frequently cited： long term viability of the Striga seed （12.5%）, difficult to control sharing of farm tools （10.8%）, expensive technologies （13.3%）, lack of adequate information （18.3%）, labour intensive （15.0%）, large farms for use of push and pull technology （1.7%） and time consuming （12.5%）. Framers used various Striga control practices but traditional methods （25%） were among the most used （25%）. Concerted effort involving researchers, extension agents and private sector are, therefore, required for wide scale dissemination and adoption of the existing modem control technologies.展开更多
Wild relatives possess potential genetic diversity for maize (<i><span style="font-family:Verdana;">Zea mays</span></i><span style="font-family:Verdana;"> L.) improvem...Wild relatives possess potential genetic diversity for maize (<i><span style="font-family:Verdana;">Zea mays</span></i><span style="font-family:Verdana;"> L.) improvement. Characterization of maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> introgression lines (ILs) is of great value to diversify the genetic base and improve the maize germplasm. Four maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> IL generations, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> BC1, BC2, BC3, and RIL, were constructed under the elite inbred background of 48-2, elite inbred line that is widely used in maize breeding in Southwestern China, and were phenotyped in different years and genotyped with 56110 SNPs. The results indicated that 48-2 had higher phenotypic performances than all the characterized ILs on most of the agronomic traits. Compared with other ILs, BC2 individuals exhibited more similar performance to 48-2 on most traits and possessed the highest kernel ratio (66.5%). Population structure and principal component analysis indicated that BC3 individuals gathered closer to 48-2 and exhibited the lowest </span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;">-introgression frequency (0.50%), while BC2 (29.06%) and RIL (18.52%) showed higher introgression frequency. The high level of genetic diversity observed in the maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> ILs demonstrated that </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">mays</span></i><span style="font-family:Verdana;"> ssp. </span><i><span style="font-family:Verdana;">mexicana </span></i><span style="font-family:Verdana;">can serve as a potential source for the enrichment of maize germplasm.</span>展开更多
Helicoverpa armigera is a key insect pest of tomatoes reducing drastically yields. The effect of the endophytic colonization of tomato plants by Beauveria bassiana using leaf spray as an inoculation method on damage a...Helicoverpa armigera is a key insect pest of tomatoes reducing drastically yields. The effect of the endophytic colonization of tomato plants by Beauveria bassiana using leaf spray as an inoculation method on damage and survival of H. armigera was assessed in a screen house. Two B. bassiana isolates (Bb 115 and Bb 11) and two tomato varieties (a local variety Tounvi and an improved variety Padma) were included in the study. The adaxial and abaxial leaf surfaces were sprayed at a concentration of 10<sup>7</sup> conidia/ml and 10<sup>9</sup> conidia/ml for each isolate and each of the two tomato varieties. Thirty days after inoculation, five discs of tomato leaf and tomato root were cut for each isolate, each concentration per isolate and for each variety. The samples were incubated at room temperature (28°C ± 2°C) and periodically checked for fungal growth. Larval survival was checked and a damage assessment was done on tomato flowers and the leaves. The results show that the lowest Mean Survival Times (MSTs) were recorded on larvae feeding on plants inoculated with Bb 11 (4.2 ± 0.8 days against 11.5 ± 0.2 days for control). Compared to the other treatments, low damage rates of the flowers of the improved variety inoculated with Bb 11 at 10<sup>9</sup> conidia/ml were recorded from the 6th Day After Inoculation (DAI). This rate remains low until the end of treatment. Overall flower damage was lower than leaf damage. The results showed large differences in pathogenicity, with most endophytic isolate belonging to Bb 11 when inoculated at 10<sup>9</sup> conidia/ml using the leaf spraying technique. Data were discussed with regard to the use of endophytism B. bassiana in an integrated tomato pest control approach.展开更多
Nutrient-balance assessments are valuable tools for both planning and monitoring the implementation of sustainable integrated soil fertility management strategies. The aim of this study was to assess nutrient flows as...Nutrient-balance assessments are valuable tools for both planning and monitoring the implementation of sustainable integrated soil fertility management strategies. The aim of this study was to assess nutrient flows as affected by cropping systems and production niche in soils of Cyabayaga watershed. yabayaga watershed is located in Nyagatare district, Eastern province of Rwanda. Production niches considered are homestead fields, remote hillside fields and wetland fields. Partial nutrient (N, P and K) flows were collected through a survey using MonQi structured questionnaire, administrated to a random sample of 35 farmers. There was nitrogen (N) and Potassium (K) negative balances (– 67.5 kg N ha<sup>-1</sup> season<sup>-1</sup> and – 7.7 kg K ha<sup>-1</sup> season<sup>-1</sup> respectively) whereas phosphorous (P) balance was positive (17.4 kg P ha<sup>-1</sup> season<sup>-1</sup>). N, P and K balances were negative in bean, maize-bean, cassava, groundnut, maize, onion, sorghum and tomato and positive in rice, banana and banana-bean. Highest amount of nutrients were significantly allocated in wetland fields while allocation of nutrients in homestead fields and remote hillside fields was almost the same. Groundnut and maize plots were experiencing highest negative nutrients balance (e.g. N balance in groundnut plot was – 40.6 N ha<sup>-1</sup> season<sup>-1</sup>). N and K balance were positive in rice and banana plots;whilst P balance was positive in banana, bean, maize, rice and tomato plots. Partial nutrients flow and balance from this study show that nutrient depletion is a problem in the study area. A special attention should be put to fertility management and alternative solution for less fertile soil (uplands in particular), especially for farm that have reduced land size. From this respect, conservation agriculture is the main farm management which could be recommended.展开更多
The degree to which soil is susceptible to erosion is measured as soil erodibility which can be influenced by different land management options.This study evaluated the dynamics of soil erodibility to tillage and soil...The degree to which soil is susceptible to erosion is measured as soil erodibility which can be influenced by different land management options.This study evaluated the dynamics of soil erodibility to tillage and soil amendments in a maize field under five consecutive cropping cycles.Tillage treatments were no-till,minimum,conventional,and grassland fallow(control).The soil amendment treatments used were no amendment(control),NPK,poultry manure(PM),and1/2NPK+1/2PM and these treatments were applied to all the tillage treatments including no-till.The study showed that tillage and soil amendment interactions had significant effects on soil erodibility(p<0.05).The mean erodibility values ranged from 13×10^(−3) to 24×10^(−3) Mg·h·MJ^(−1)·mm^(−1) in the following order:control<conventional tillage<minimum tillage<no-till.For the soil amendments,erodibility varied from NPK>poultry manure=1/2NPK+1/2PM>control(undisturbed grassland).Regardless of the type of soil amendment,the soil erodibility under conventional tillage was significantly lower than that under no-till and minimum tillage systems.The relationship between erodibility and easily measured soil parameters,such as%sand greater than 100μm,%silt plus very fine sand,clay,and saturated hydraulic conductivity,were significant at p<0.05.The higher contribution(86%)of sand and silt to the variation in erodibility indicates that any other indices of erodibility based on particle size distribution,apart from the nomograph,could satisfactorily predict erodibility values.展开更多
A field experiment was conducted at Kpongu in the Upper West region of Ghana to determine the added benefits in grain yield of maize derived from the concurrent use of manure and mineral fertilizer, and their cost eff...A field experiment was conducted at Kpongu in the Upper West region of Ghana to determine the added benefits in grain yield of maize derived from the concurrent use of manure and mineral fertilizer, and their cost effectiveness. Factorial combinations of cattle manure and mineral fertilizer each at 0, 50 and 100% of their recommended rates were evaluated in both the field and the laboratory studies. The treatments were applied in a randomized complete block design with three replications on the field. The same treatments were applied in the incubation study in a completely randomized design. The use of 100% NPK （Nitrogen, Phosphorus, Potassium） ＋ 5 t manure gave the highest grain yield of 4,678 kg·ha^-1. Synergistic interactions resulting in added benefits in grain yield were observed in all the combined nutrient inputs except 50% NPK ＋ 2.5 t manure which accrued an added disadvantage of 44 kg·ha^-1. Economic analysis proved that 100% NPK ＋ 2.5 t manure and 50% NPK ＋ 5 t manure were the most economically viable combined treatments in terms of grain yield. Based on the results from this study, resource poor farmers in the Upper West region of Ghana may reduce mineral fertilizer recommended rates by 50% and supplement it with 5 t quality （N 〉2.5%） cattle manure without compromising yield and profit.展开更多
The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18...The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18 and 21 fin clips per river population,respectively and subjected to polymerase chain reaction.A total of 96 sequences,each with 671 bp were obtained with 38(5.6%)polymorphic,27(3.8%)parsimoniously informative and 659(98.2%)conserved sites.Mean nucleotide composition was C=28.07%,T=29.43%,A=22.18%,G=20.32%.A total of 40 haplotypes with 38 unique sequences as well as 24 substitutions with 22 transversions and two transitions were obtained.Nucleotide diversity among populations ranged from 0.00184 to 0.00888 representing Ibbi and Imo,respectively while haplotype diversity ranged from 0.77056 to 0.95000 also,from Ibbi and Imo,respectively.Analyses of molecular variance showed that the intra-population variation accounted for 50.05%.Topology from phylogenetic analyses revealed that P.obscura from Imo River was distinctly different from the rest.展开更多
The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hym...The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hymenoptera： Braconidae） was investi- gated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata （cowpea）, Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or E unguiculata at 25℃, or on P. santalinoides at 25℃ or 29℃. Apanteles taragamae had the shortest development time on artificial diet at both 25℃ and 29℃ while the longest development time was recorded on L. sericeus at 29℃. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25℃ varied among feeding substrates, but not at 29℃. Survival rate of parasitized larvae depends on the feeding sub- strate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus （MaviMNPV） killed larger proportions of parasitized larvae at 25℃ than at 29℃, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth-high mortality hypothesis.展开更多
Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease （A...Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease （ACMD）, bacterial blight （CBB）, anthracnose （CAD）, and green mite （CGM）, compared to TMS30572, an elite cultivar widely adopted in Africa. Considerable genotypic variation was observed among cultivars for resistance to ACMD and CGM but not for CBB and CAD. The lowest mean incidence of 12% and severity of 1.8 on a scale of 1-5 for ACMD was recorded for Atu, a landrace with farmer acceptable qualities. In comparison, the improved cultivar, TMS 30572, had a mean disease incidence of 72% and a severity score of 2.8. Another landrace, MS-20 had the lowest CGM damage score （2.1） while TMS 30572 emerged as one of the susceptible cultivars with a damage score of 3. Additional sources of resistance to ACMD and CGM that may possibly be better than the popular improved cultivar, TMS 30572, were identified in this study. These could serve as novel sources of additional genes to complement existing resources for elite cassava breeding in Africa.展开更多
The study was conducted to assess the chemical composition of the haulms of 4 dual-purpose groundnut(Arachis hypogaea L.) varieties and their effects on the growth and hematology of Djallonke rams. The groundnut varie...The study was conducted to assess the chemical composition of the haulms of 4 dual-purpose groundnut(Arachis hypogaea L.) varieties and their effects on the growth and hematology of Djallonke rams. The groundnut varieties were ICGV 97049(Obolo), ICGX SM 87057(Yenyawoso), RMP 12(Azivivi) and Manipinta. Rams(live weight 15.0 ± 3.0 kg) were randomly assigned to 4 sole groundnut haulm meal(GHM) treatments, with 4 rams each in an individual pen per treatment(total n = 16 rams). Samples of the groundnut haulms were milled and analyzed for crude protein(CP), neutral detergent fiber(NDF)and acid detergent fiber(ADF). The CP concentration was higher(P < 0.05) in Azivivi, Manipinta and Yenyawoso than in Obolo. The highest(P < 0.05) NDF and ADF fractions were obtained in Obolo. Whilst no significant difference was reported in total and daily dry matter(DM) intake among the varieties,CP,NDF and ADF intake all differed between Obolo and other varieties. The apparent nutrient digestibility did not differ(P> 0.05) when the Djallonke rams were fed the haulms. However, significant differences were observed in final live weight and average daily live weight gain. Rams fed the Yenyawoso variety had higher(P < 0.05) final live weight and average daily live weight gain compared with those fed Obolo and Azivivi varieties. Consumption of any of the 4 varieties of groundnut haulms by Djallonke rams did not have any harmful effect on their red and white blood cell numbers and hemoglobin concentration.The study revealed that the different varieties of groundnut haulms differ in nutrient composition and also affect the growth performance of the rams. The Yenyawoso variety may be used as a sole diet for fattening Djallonke rams.展开更多
Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.H...Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.Here,we investigated the performance of piperonyl-butoxide(PBO)-pyrethroid[Permanet 3.0(P3.0)]and dual active ingredients(AI)nets[Interceptor G2(IG2):containing pyrethroids and chlorfenapyr and Royal Guard(RG):containing pyrethroids and pyriproxyfen]compared to pyrethroid-only net Royal Sentry(RS)against pyrethroid-resistant malaria vectors in Cameroon.Methods The efficacy of these tools was firstly evaluated onAnopheles gambiae s.l.andAnopheles funestus s.l.from Gounougou,Mibellon,Mangoum,Nkolondom,and Elende using cone/tunnel assays.In addition,experimental hut trials(EHT)were performed to evaluate the performance of unwashed and 20 times washed nets in semi-field conditions.Furthermore,pyrethroid-resistant markers were genotyped in dead vs alive,blood-fed vs unfed mosquitoes after exposure to the nets to evaluate the impact of these markers on net performance.The XLSTAT software was used to calculate the various entomological outcomes and the Chi-square test was used to compare the efficacy of various nets.The odds ratio and Fisher exact test were then used to establish the statistical significance of any association between insecticide resistance markers and bed net efficacy.Results Interceptor G2 was the most effective net against wild pyrethroid-resistantAn.funestus followed by Permanet 3.0.In EHT,this net induced up to 87.8%mortality[95%confidence interval(CI):83.5-92.1%)and 55.6%(95%CI:48.5-62.7%)after 20 washes whilst unwashed pyrethroid-only net(Royal Sentry)killed just 18.2%(95%CI:13.4-22.9%)of host-seekingAn.funestus.The unwashed Permanet 3.0 killed up to 53.8%(95%CI:44.3-63.4%)of field-resistant mosquitoes and 47.2%(95%CI:37.7-56.7%)when washed 20 times,and the Royal Guard 13.2%(95%CI:9.0-17.3%)for unwashed net and 8.5%(95%CI:5.7-11.4%)for the 20 washed net.Interceptor G2,Permanet 3.0,and Royal Guard provided better personal protection(blood-feeding inhibition 66.2%,77.8%,and 92.8%,respectively)compared to pyrethroid-only net Royal Sentry(8.4%).Interestingly,a negative association was found betweenkdrw and the chlorfenapyr-based net Interceptor G2(χ^(2)=138;P<0.0001)with homozygote-resistant mosquitoes predominantly found in the dead ones.Conclusions The high mortality recorded with Interceptor G2 against pyrethroid-resistant malaria vectors in this study provides first semi-field evidence of high efficacy against these major malaria vectors in Cameroon encouraging the implementation of this novel net for malaria control in the country.However,the performance of this net should be established in other locations and on other major malaria vectors before implementation at a large scale.展开更多
Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to mon...Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations.In this study,we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa.Methods:Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon(Njombe-Penja,Nkolondom,and Mangoum),the Democratic Republic of Congo(Ndjili-Brasserie),Ghana(Obuasi),and Uganda(Mayuge).Using the CDC bottle test,we compared the effect of three different solvents(ethanol,acetone,MERO)on the efficacy of neonicotinoids againstAnopheles gambiae s.l.In addition,TaqMan assays were used to genotype key pyrethroid-resistant markers inAn.gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin.Results:Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin(11.4-51.9% mortality in Nkolondom,31.7-48.2% in Mangoum,34.6-56.1% in Mayuge,39.4-45.6% in Obuasi,83.7-89.3% in Congo and 71.1-95.9% in Njombe pendja)compared to acetone+MERO for which 100% mortality were observed for all the populations.Similar observations were done for imidacloprid and acetamiprid.Synergist assays(PBO,DEM and DEF)with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility.A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors(OR=0.5;P=0.02).However,the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes(OR=2.10;P=0.013).Conclusions:This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality,thus possibly overestimating resistance,whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development.Therefore,we recommend monitoring the susceptibility using both acetone alone and acetone+MERO(4μg/ml for clothianidin)to capture the accurate resistance profile of the mosquito populations.展开更多
文摘Cowpea, Vigna unguiculata (L.) Walp. is an economically important seed legume that helps combat food and nutrition insecurity in the Sahel, particularly Niger. However, its yield remains low due to insect pest attacks. This study was conducted at a station and in seven villages in the Maradi and Tahoua regions. It aimed to test the effectiveness of neem seed biopesticides [Azadirachta indica A. Juss] and sanitized human urine for integrated insect pest management. The cowpea variety UAM09 1055-6 was used for the experiments. The experimental trial was a Fisher block design consisting of five treatments: neem oil, neem seed extract (NSE), hygienized human urine (HHU), chemical pesticide, and a control, replicated five times at the station and twice in farmers’ environments. The study shows that Megalurothrips sjostedti Trybom, Clavigralla tomentosicollis Stål and Maruca vitrata Fabricius are the main insect pests. Plots treated with synthetic pesticides were the least infested by C. tomentosicollis. They were followed by neem seed extract and HHU treatments, which recorded an infestation level of 2.44 and 20.5 times lower than controls at the station and in farming environments. The density of thrips was 1.06 to 32.6 times lower in treated plots compared to controls. The proportion of pods damaged by M. vitrata was 1.95, 2.55, and 2.77 times lower in plots treated with HHU, NSE, and synthetic pesticide, respectively, compared to controls. Grain yields were 1.80 and 2.62 times higher in UHH and NSE treatments compared to control plots, both at the station and in farmers’ environments. A yield increase of 44.58% and 61.92% was noted for these treatments at the station and in farmers’ environments, respectively. These results may promote the dissemination of NSE and HHU biopesticide technologies in rural areas as an alternative method for integrated pest management of cowpeas.
文摘Cultivating traditional upland rice cultivars on nutrient depleted soil causes poor and low yield. Little attention is paid to performance of inter-specific NERICA cultivars grown on nutrient deficient soil augmented with different types of compost. Therefore, field trials were conducted during 2010 and 2011 planting seasons in Ibadan to evaluate growth, dry matter, nutrient uptake efficiency and grain yield of upland rice grown on nutrient deficient soil augmented with different types of compost. There were nine treatments comprising of three upland rice cultivars: NERICA I, NERICA II and Ofada, two compost types applied at the rate of 8 t·ha-1: poultry dropping + maize stover (PDMC) and cattle dung + maize stover (CDMC) and control. The treatments were laid out in randomized complete block design and replicated three times. CDMC enhanced growth, nutrient use efficiency, dry matter and grain yield of upland rice cultivars. Performance of Ofada was better than NERICA cultivars. N (24.55 g), P (12.45 g) and K (35.41 g) uptake concentration and grain yield (5.45 t/ha) were highest in Ofada plots augmented with CDMC. Residual effect of compost on growth, yield and nutrient uptake efficiency of upland rice on nutrient deficient soil was marginal.
基金financially supported by VLIRfunded project ‘Forest Rehabilitation through Natural Regeneration’DAAD
文摘In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at:(1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures;(2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated(n = 3) 5 and10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly(p \ 0.05) greater than that from Euclea.racemosa. Average daily fuelwood consumption per person was(0.63 ± 0.2) kg day^(-1). This means that the total biomass(27.5 Mg year^(-1)) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents(95%) confirmed that they travel more than10 km day^(-1) to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.
文摘Whole grain cereals are important dietary sources for management of metabolic diseases due to the bioactive components they contain.Hence,this study investigated enzymes(pancreatic lipase,-amylase,-glucosidase,xanthine oxidase and angiotensin 1-converting enzyme)inhibitory property,antioxidant activity and phenolics profile of raw and roasted red sorghum(Sorghum bicolor)grains in vitro.Extracts of flours of raw and roasted(150◦C and 180◦C,for 20 min)grains were assayed for enzymes inhibitory and antioxidant activities using spectrophotometric methods;while their phenolic constituents were characterized using HPLC-DAD.The raw grains exhibited strong enzymes inhibitory and antioxidant activities,and contained phenolic acids(gallic,chlorogenic,caffeic,ellagic and p-coumaric acids)and flavonoids(quercetin,luteolin and apigenin).However,whereas the enzymes inhibitory activity and levels of the phenolic compounds in the grains decreased significantly(p<0.05)with increasing roasting temperature,the antioxidant activity increased.Hence,roasting at high temperature may not be recommended for the optimum retention of the enzymes inhibitory property and phenolic compounds of red sorghum grains.
文摘During the last decade, Jatropha curcas L. (J. curcas) has gained much attention worldwide as biofuel crop. Although its cultivation is promoted in the Sahel, there is a surprising lack of data on its water use regulation and growth in this region. Here, we investigated, in semi-controlled conditions, leaf transpiration and growth of six accessions of J. curcas at seedling stage under natural changing in vapour pressure deficit (VPD) and progressive soil drying in Senegal. The experimental layout was a randomized complete bloc design and after 3 months of growth arranged to a split-plot at the implementation of water stress to facilitate irrigation. Under well water condition, there was no significant difference between accessions for leave transpiration that was positively correlated to VPD with high values recorded between 13 h and 14 h pm. Accessions of J. curcas used in this study showed closed thresholds at which transpiration declined except accession from Ndawene that threshold was lower (0.30). There is no significant difference between accessions for growth during the experimentation period. In 3 months, we recorded 23.57 g for the aboveground dry biomass and seedlings had about 14 leaves and 24.3 cm height. Positive linear correlation was recorded between aboveground biomass and root dry weight (p J. curcas might need complement irrigation for a better growth of seedlings especially during the dry season.
文摘Understanding the nature and extent of association between yield and yield related traits is the prerequisite study for any underutilized crop improvements of sustainable genetic enhancement. However, there is a lack of sufficient information on seed yield and related trait correlation and path coefficient analysis of cowpea in Ethiopia. To fill the existing knowledge gap, the present study was conducted to determine the nature and extent of phenotypic and genotypic correlation and path coefficient analysis among 18 quantitative traits. A total of 324 cowpea landraces were tested in 18 × 18 simple lattice design at Melkassa Agricultural Research Center and Miesso sub center during 2016 cropping season. The magnitude of genotypic correlations was higher than phenotypic correlations in most traits at both locations;this implies that the traits under consideration were genetically controlled. Seed yield was positively and highly significantly correlated with most of the traits at phenotypic and genotypic levels, indicating the presence of strong inherited association between seed yield and the other 17 traits. Almost all traits genotypic direct and indirect effects were higher than the phenotypic direct and indirect effects;this indicated that the other traits had a strong genetically inherited relationship with seed yield. Genotypic path coefficient analysis revealed that days to flowering, biomass and harvest index at Miesso, and seed thickness, plant height, days to maturity and biomass at Melkassa had relatively high positive direct effect on seed yield. However, seed width and hundred seed weight had exerted negative direct effect on seed yield at each location. Phenotypic path coefficient analysis showed that biomass and harvest index had exerted high positive direct effect on seed yield at both locations. From these results it can be concluded from this study that seed yield in cowpea can be improved by focusing on traits pod length, seed length, seed thickness, seed width, biomass and harvest index at both locations. The information obtained from this study can be used for genetic enhancement of cowpea thereby developing high yielding varieties.
文摘The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung （D）, nitrogen （N） and phosphorus （P） in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol.
文摘The production of maize is constrained by parasitic weeds, particularly Striga. A study was carried out to document farmers＇ knowledge, attitude and practices on Striga control among smallholder farmers across three districts： Kisumu West, Busia and Teso South of Western Kenya. A multistage sampling technique was used to select the locations and farmers to be interviewed. A semi structured, open and closed ended questionnaire was administered leading to field experiment. Besides village meetings （39.2%）, farmers got informed on farming methods under Striga weed farms and its control technologies through neighbours （2.5%）, workshops and trainings （5.0%）, field schools （3.7%）, media （7.5%） and extension agents （10.8%）. The attitudes of farmers towards Striga control varied but frequently cited： long term viability of the Striga seed （12.5%）, difficult to control sharing of farm tools （10.8%）, expensive technologies （13.3%）, lack of adequate information （18.3%）, labour intensive （15.0%）, large farms for use of push and pull technology （1.7%） and time consuming （12.5%）. Framers used various Striga control practices but traditional methods （25%） were among the most used （25%）. Concerted effort involving researchers, extension agents and private sector are, therefore, required for wide scale dissemination and adoption of the existing modem control technologies.
文摘Wild relatives possess potential genetic diversity for maize (<i><span style="font-family:Verdana;">Zea mays</span></i><span style="font-family:Verdana;"> L.) improvement. Characterization of maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> introgression lines (ILs) is of great value to diversify the genetic base and improve the maize germplasm. Four maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> IL generations, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> BC1, BC2, BC3, and RIL, were constructed under the elite inbred background of 48-2, elite inbred line that is widely used in maize breeding in Southwestern China, and were phenotyped in different years and genotyped with 56110 SNPs. The results indicated that 48-2 had higher phenotypic performances than all the characterized ILs on most of the agronomic traits. Compared with other ILs, BC2 individuals exhibited more similar performance to 48-2 on most traits and possessed the highest kernel ratio (66.5%). Population structure and principal component analysis indicated that BC3 individuals gathered closer to 48-2 and exhibited the lowest </span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;">-introgression frequency (0.50%), while BC2 (29.06%) and RIL (18.52%) showed higher introgression frequency. The high level of genetic diversity observed in the maize-</span><i><span style="font-family:Verdana;">mexicana</span></i><span style="font-family:Verdana;"> ILs demonstrated that </span><i><span style="font-family:Verdana;">Z</span></i><span style="font-family:Verdana;">. </span><i><span style="font-family:Verdana;">mays</span></i><span style="font-family:Verdana;"> ssp. </span><i><span style="font-family:Verdana;">mexicana </span></i><span style="font-family:Verdana;">can serve as a potential source for the enrichment of maize germplasm.</span>
文摘Helicoverpa armigera is a key insect pest of tomatoes reducing drastically yields. The effect of the endophytic colonization of tomato plants by Beauveria bassiana using leaf spray as an inoculation method on damage and survival of H. armigera was assessed in a screen house. Two B. bassiana isolates (Bb 115 and Bb 11) and two tomato varieties (a local variety Tounvi and an improved variety Padma) were included in the study. The adaxial and abaxial leaf surfaces were sprayed at a concentration of 10<sup>7</sup> conidia/ml and 10<sup>9</sup> conidia/ml for each isolate and each of the two tomato varieties. Thirty days after inoculation, five discs of tomato leaf and tomato root were cut for each isolate, each concentration per isolate and for each variety. The samples were incubated at room temperature (28°C ± 2°C) and periodically checked for fungal growth. Larval survival was checked and a damage assessment was done on tomato flowers and the leaves. The results show that the lowest Mean Survival Times (MSTs) were recorded on larvae feeding on plants inoculated with Bb 11 (4.2 ± 0.8 days against 11.5 ± 0.2 days for control). Compared to the other treatments, low damage rates of the flowers of the improved variety inoculated with Bb 11 at 10<sup>9</sup> conidia/ml were recorded from the 6th Day After Inoculation (DAI). This rate remains low until the end of treatment. Overall flower damage was lower than leaf damage. The results showed large differences in pathogenicity, with most endophytic isolate belonging to Bb 11 when inoculated at 10<sup>9</sup> conidia/ml using the leaf spraying technique. Data were discussed with regard to the use of endophytism B. bassiana in an integrated tomato pest control approach.
文摘Nutrient-balance assessments are valuable tools for both planning and monitoring the implementation of sustainable integrated soil fertility management strategies. The aim of this study was to assess nutrient flows as affected by cropping systems and production niche in soils of Cyabayaga watershed. yabayaga watershed is located in Nyagatare district, Eastern province of Rwanda. Production niches considered are homestead fields, remote hillside fields and wetland fields. Partial nutrient (N, P and K) flows were collected through a survey using MonQi structured questionnaire, administrated to a random sample of 35 farmers. There was nitrogen (N) and Potassium (K) negative balances (– 67.5 kg N ha<sup>-1</sup> season<sup>-1</sup> and – 7.7 kg K ha<sup>-1</sup> season<sup>-1</sup> respectively) whereas phosphorous (P) balance was positive (17.4 kg P ha<sup>-1</sup> season<sup>-1</sup>). N, P and K balances were negative in bean, maize-bean, cassava, groundnut, maize, onion, sorghum and tomato and positive in rice, banana and banana-bean. Highest amount of nutrients were significantly allocated in wetland fields while allocation of nutrients in homestead fields and remote hillside fields was almost the same. Groundnut and maize plots were experiencing highest negative nutrients balance (e.g. N balance in groundnut plot was – 40.6 N ha<sup>-1</sup> season<sup>-1</sup>). N and K balance were positive in rice and banana plots;whilst P balance was positive in banana, bean, maize, rice and tomato plots. Partial nutrients flow and balance from this study show that nutrient depletion is a problem in the study area. A special attention should be put to fertility management and alternative solution for less fertile soil (uplands in particular), especially for farm that have reduced land size. From this respect, conservation agriculture is the main farm management which could be recommended.
文摘The degree to which soil is susceptible to erosion is measured as soil erodibility which can be influenced by different land management options.This study evaluated the dynamics of soil erodibility to tillage and soil amendments in a maize field under five consecutive cropping cycles.Tillage treatments were no-till,minimum,conventional,and grassland fallow(control).The soil amendment treatments used were no amendment(control),NPK,poultry manure(PM),and1/2NPK+1/2PM and these treatments were applied to all the tillage treatments including no-till.The study showed that tillage and soil amendment interactions had significant effects on soil erodibility(p<0.05).The mean erodibility values ranged from 13×10^(−3) to 24×10^(−3) Mg·h·MJ^(−1)·mm^(−1) in the following order:control<conventional tillage<minimum tillage<no-till.For the soil amendments,erodibility varied from NPK>poultry manure=1/2NPK+1/2PM>control(undisturbed grassland).Regardless of the type of soil amendment,the soil erodibility under conventional tillage was significantly lower than that under no-till and minimum tillage systems.The relationship between erodibility and easily measured soil parameters,such as%sand greater than 100μm,%silt plus very fine sand,clay,and saturated hydraulic conductivity,were significant at p<0.05.The higher contribution(86%)of sand and silt to the variation in erodibility indicates that any other indices of erodibility based on particle size distribution,apart from the nomograph,could satisfactorily predict erodibility values.
文摘A field experiment was conducted at Kpongu in the Upper West region of Ghana to determine the added benefits in grain yield of maize derived from the concurrent use of manure and mineral fertilizer, and their cost effectiveness. Factorial combinations of cattle manure and mineral fertilizer each at 0, 50 and 100% of their recommended rates were evaluated in both the field and the laboratory studies. The treatments were applied in a randomized complete block design with three replications on the field. The same treatments were applied in the incubation study in a completely randomized design. The use of 100% NPK （Nitrogen, Phosphorus, Potassium） ＋ 5 t manure gave the highest grain yield of 4,678 kg·ha^-1. Synergistic interactions resulting in added benefits in grain yield were observed in all the combined nutrient inputs except 50% NPK ＋ 2.5 t manure which accrued an added disadvantage of 44 kg·ha^-1. Economic analysis proved that 100% NPK ＋ 2.5 t manure and 50% NPK ＋ 5 t manure were the most economically viable combined treatments in terms of grain yield. Based on the results from this study, resource poor farmers in the Upper West region of Ghana may reduce mineral fertilizer recommended rates by 50% and supplement it with 5 t quality （N 〉2.5%） cattle manure without compromising yield and profit.
基金The authors appreciate the International Foundation for Science(IFS),Stockholm,Sweden for funding this research through their Grant Number I-2-A-6090-1 provided to Friday Elijah Osho to study the phenotypic and genetic characterization of Parachanna obscura from Nigeria’s freshwater environments.
文摘The study investigated the genetic variation of Parachanna obscura from five rivers(Anambra,Ibbi,Imo,Katsina-Ala and Ogun)in Nigeria using the mitochondrial cytochrome oxidase 1 gene.DNA was extracted from 19,22,16,18 and 21 fin clips per river population,respectively and subjected to polymerase chain reaction.A total of 96 sequences,each with 671 bp were obtained with 38(5.6%)polymorphic,27(3.8%)parsimoniously informative and 659(98.2%)conserved sites.Mean nucleotide composition was C=28.07%,T=29.43%,A=22.18%,G=20.32%.A total of 40 haplotypes with 38 unique sequences as well as 24 substitutions with 22 transversions and two transitions were obtained.Nucleotide diversity among populations ranged from 0.00184 to 0.00888 representing Ibbi and Imo,respectively while haplotype diversity ranged from 0.77056 to 0.95000 also,from Ibbi and Imo,respectively.Analyses of molecular variance showed that the intra-population variation accounted for 50.05%.Topology from phylogenetic analyses revealed that P.obscura from Imo River was distinctly different from the rest.
文摘The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hymenoptera： Braconidae） was investi- gated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata （cowpea）, Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or E unguiculata at 25℃, or on P. santalinoides at 25℃ or 29℃. Apanteles taragamae had the shortest development time on artificial diet at both 25℃ and 29℃ while the longest development time was recorded on L. sericeus at 29℃. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25℃ varied among feeding substrates, but not at 29℃. Survival rate of parasitized larvae depends on the feeding sub- strate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus （MaviMNPV） killed larger proportions of parasitized larvae at 25℃ than at 29℃, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth-high mortality hypothesis.
文摘Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease （ACMD）, bacterial blight （CBB）, anthracnose （CAD）, and green mite （CGM）, compared to TMS30572, an elite cultivar widely adopted in Africa. Considerable genotypic variation was observed among cultivars for resistance to ACMD and CGM but not for CBB and CAD. The lowest mean incidence of 12% and severity of 1.8 on a scale of 1-5 for ACMD was recorded for Atu, a landrace with farmer acceptable qualities. In comparison, the improved cultivar, TMS 30572, had a mean disease incidence of 72% and a severity score of 2.8. Another landrace, MS-20 had the lowest CGM damage score （2.1） while TMS 30572 emerged as one of the susceptible cultivars with a damage score of 3. Additional sources of resistance to ACMD and CGM that may possibly be better than the popular improved cultivar, TMS 30572, were identified in this study. These could serve as novel sources of additional genes to complement existing resources for elite cassava breeding in Africa.
基金Africa Research in Sustainable Intensification for the Next Generation (RISING) project of the International Institute of Tropical Agriculture(IITA)
文摘The study was conducted to assess the chemical composition of the haulms of 4 dual-purpose groundnut(Arachis hypogaea L.) varieties and their effects on the growth and hematology of Djallonke rams. The groundnut varieties were ICGV 97049(Obolo), ICGX SM 87057(Yenyawoso), RMP 12(Azivivi) and Manipinta. Rams(live weight 15.0 ± 3.0 kg) were randomly assigned to 4 sole groundnut haulm meal(GHM) treatments, with 4 rams each in an individual pen per treatment(total n = 16 rams). Samples of the groundnut haulms were milled and analyzed for crude protein(CP), neutral detergent fiber(NDF)and acid detergent fiber(ADF). The CP concentration was higher(P < 0.05) in Azivivi, Manipinta and Yenyawoso than in Obolo. The highest(P < 0.05) NDF and ADF fractions were obtained in Obolo. Whilst no significant difference was reported in total and daily dry matter(DM) intake among the varieties,CP,NDF and ADF intake all differed between Obolo and other varieties. The apparent nutrient digestibility did not differ(P> 0.05) when the Djallonke rams were fed the haulms. However, significant differences were observed in final live weight and average daily live weight gain. Rams fed the Yenyawoso variety had higher(P < 0.05) final live weight and average daily live weight gain compared with those fed Obolo and Azivivi varieties. Consumption of any of the 4 varieties of groundnut haulms by Djallonke rams did not have any harmful effect on their red and white blood cell numbers and hemoglobin concentration.The study revealed that the different varieties of groundnut haulms differ in nutrient composition and also affect the growth performance of the rams. The Yenyawoso variety may be used as a sole diet for fattening Djallonke rams.
基金This work was supported by the PIIVEC operational research project(PV/OP2-03/TW to MT under the MRC grant MR/PO27873/1),the Renewal Wellcome Trust Senior Research Fellowship in Biomedical Sciences(217188/Z/19/Z),and the BMGF Grant(INV-006003)awarded to CSW.
文摘Background The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools.Here,we investigated the performance of piperonyl-butoxide(PBO)-pyrethroid[Permanet 3.0(P3.0)]and dual active ingredients(AI)nets[Interceptor G2(IG2):containing pyrethroids and chlorfenapyr and Royal Guard(RG):containing pyrethroids and pyriproxyfen]compared to pyrethroid-only net Royal Sentry(RS)against pyrethroid-resistant malaria vectors in Cameroon.Methods The efficacy of these tools was firstly evaluated onAnopheles gambiae s.l.andAnopheles funestus s.l.from Gounougou,Mibellon,Mangoum,Nkolondom,and Elende using cone/tunnel assays.In addition,experimental hut trials(EHT)were performed to evaluate the performance of unwashed and 20 times washed nets in semi-field conditions.Furthermore,pyrethroid-resistant markers were genotyped in dead vs alive,blood-fed vs unfed mosquitoes after exposure to the nets to evaluate the impact of these markers on net performance.The XLSTAT software was used to calculate the various entomological outcomes and the Chi-square test was used to compare the efficacy of various nets.The odds ratio and Fisher exact test were then used to establish the statistical significance of any association between insecticide resistance markers and bed net efficacy.Results Interceptor G2 was the most effective net against wild pyrethroid-resistantAn.funestus followed by Permanet 3.0.In EHT,this net induced up to 87.8%mortality[95%confidence interval(CI):83.5-92.1%)and 55.6%(95%CI:48.5-62.7%)after 20 washes whilst unwashed pyrethroid-only net(Royal Sentry)killed just 18.2%(95%CI:13.4-22.9%)of host-seekingAn.funestus.The unwashed Permanet 3.0 killed up to 53.8%(95%CI:44.3-63.4%)of field-resistant mosquitoes and 47.2%(95%CI:37.7-56.7%)when washed 20 times,and the Royal Guard 13.2%(95%CI:9.0-17.3%)for unwashed net and 8.5%(95%CI:5.7-11.4%)for the 20 washed net.Interceptor G2,Permanet 3.0,and Royal Guard provided better personal protection(blood-feeding inhibition 66.2%,77.8%,and 92.8%,respectively)compared to pyrethroid-only net Royal Sentry(8.4%).Interestingly,a negative association was found betweenkdrw and the chlorfenapyr-based net Interceptor G2(χ^(2)=138;P<0.0001)with homozygote-resistant mosquitoes predominantly found in the dead ones.Conclusions The high mortality recorded with Interceptor G2 against pyrethroid-resistant malaria vectors in this study provides first semi-field evidence of high efficacy against these major malaria vectors in Cameroon encouraging the implementation of this novel net for malaria control in the country.However,the performance of this net should be established in other locations and on other major malaria vectors before implementation at a large scale.
文摘Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations.In this study,we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa.Methods:Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon(Njombe-Penja,Nkolondom,and Mangoum),the Democratic Republic of Congo(Ndjili-Brasserie),Ghana(Obuasi),and Uganda(Mayuge).Using the CDC bottle test,we compared the effect of three different solvents(ethanol,acetone,MERO)on the efficacy of neonicotinoids againstAnopheles gambiae s.l.In addition,TaqMan assays were used to genotype key pyrethroid-resistant markers inAn.gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin.Results:Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin(11.4-51.9% mortality in Nkolondom,31.7-48.2% in Mangoum,34.6-56.1% in Mayuge,39.4-45.6% in Obuasi,83.7-89.3% in Congo and 71.1-95.9% in Njombe pendja)compared to acetone+MERO for which 100% mortality were observed for all the populations.Similar observations were done for imidacloprid and acetamiprid.Synergist assays(PBO,DEM and DEF)with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility.A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors(OR=0.5;P=0.02).However,the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes(OR=2.10;P=0.013).Conclusions:This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality,thus possibly overestimating resistance,whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development.Therefore,we recommend monitoring the susceptibility using both acetone alone and acetone+MERO(4μg/ml for clothianidin)to capture the accurate resistance profile of the mosquito populations.
