Land Use Impacts on Water Quality of Rivers draining from Mulanje Mountain: A Case of Ruo River in the Southern Malawi

A research study was carried out to determine the effects of different land uses on the water quality of Ruo River. Water sampling was done both in the upper and the middle sections of the river. The water samples were analysed for pH, total dissolved solids (TDS), electrical conductivity (EC), dissolved oxygen (DO), sulphates, chloride, bicarbonates, nitrates, phosphates, fluoride, sodium, potassium, cadmium and Escherichia coli using standard methods. Land uses in the area significantly affected the concentration of EC, TDS, sulphates, potassium and sodium (p ≤ 0.05) while pH, dissolved oxygen, chloride, bicarbonates, nitrates, phosphates and E-coli did not significantly fluctuate with land use changes in the area (p ≥ 0.05). The effect of seasons was significant on pH, dissolved oxygen, phosphates, chloride, bicarbonates and sodium (p ≤ 0.05) but not on electrical conductivity, total dissolved solids, sulphates, nitrates, lead, potassium and e coli in Ruo River. The research recommends an integrated water resources management approach where all users and relevant stakeholders should take an active role in the conservation of Ruo River catchment in order to avoid further degradation of the catchment through different land uses.Keywords: Ruo River; Mulanje Mountain; Land use changes; Water quality; smallholder farmers; Estate farmer

Potential of genetics for aquaculture development in Africa

Aquaculture in Africa is fairly insignificant by world standards and accounts for a mere 0.4 per cent of global aquaculture production. The application of genetics can play an important role in efforts to increase aquaculture production in Africa through methods such as selective breeding, hybridization, chromosome manipulation and use of YY “supermales”. Other issues that need to be addressed are limited genetic research facilities, funding, human capacity and suitable species for aquaculture

Genetic differentiation and diversity of Adansonia digitata L (baobab) in Malawi using microsatellite markers

Baobab (Adansonia digitata L) belonging to Bombacaceae family, is one of the most widely used indigenous priority tree species in sub-Saharan Africa, valued in the cosmetic industry for its seed oil, and powdery fruit pulp for juice making. Baobab has high potential for domestication in southern Africa, therefore understanding its genetic diversity and population structuring is warranted. The study investigated the level of genetic diversity and differentiation of five populations of A. digitata L. sampled from four diverse silvicultural zones in Malawi. Variation at nine microsatellite loci were examined in 150 individual trees. Low mean genetic diversity was expressed through genetic diversity indices: Nei’s genetic diversity (h, 0.18 ± 0.03), Shannon Information Index (I, 0.21 ± 0.07), observed number of alleles (na, 1.47 ± 0.10), effective number of alleles (na, 1.23 ± 0.04) and percentage polymorphic loci (pp, 48%). The low genetic variation found is attributed to the population growing in marginal areas of genetic centre of diversity of the species, anthropogenic factors and founder effects. Moderate genetic differentiation was observed among populations (Gst = 0.13) indicating the presence of a large number of common alleles resulting in a homogenisation effect. Clustering of individual trees by genetic similarity coefficients indicated that mainland trees were genetically closer than the trees on Likoma Island. Mantel’s test showed a weak positive insignificant correlation (Z = 0.12; P = 0.64) between genetic distance among populations and actual distance on the ground implying that geneflow was not directly influenced by isolation by distance. The results suggest that seed distribution and tree improvement should recognise the presence of ecotypes and conservation measures should protect all the populations due to existence of private alleles which are of adaptive importance.Mzuzu University and Stellenbosch University.http://www.springer.com/life+sci/forestry/journal/1045

Urinary schistosomiasis among preschool children in Malengachanzi, Nkhotakota District, Malawi: Prevalence and risk factors

Aim: This study was designed to determine the prevalence of and risk factors for schistosomiasis among a group of preschool children in Malawi. Schistosomiasis burden among preschoolers in Malawi is not well documented in the literature.Methods: This study used field research (in the form of a snail survey), laboratory work (urinalysis and microscopy for parasite identification), and questionnaireguided interviews to determine the prevalence of and risk factors for urinary schistosomiasis among children, aged between 6 and 60 months, in Malengachanzi, Nkhotakota District, Malawi.Results: Urinary schistosomiasis prevalence among preschool children was 13%. Of the factors evaluated, only age (P = 0.027) was statistically significantly associated with urinary schistosomiasis risk. Four-year-old preschool children were five times more likely to contract urinary schistosomiasis than twoyear-old children (odds ratio [OR] = 5.255; 95% confidence interval [CI] = 1.014-27.237; P = 0.048). Increased contact with infested water among older children likely explains much of their increased risk. Infestation was evidenced by the presence of infected Bulinus globosus snails in the water contact points surveyed. Multiple regression analysis showed that visiting water contact sites daily (OR = 0.898, 95% CI = 0.185-4.350, P = 0.894), bathing in these sites (OR = 9.462, 95% CI = 0.036-0.00, P = 0.430) and lack of knowledge, among caregivers, regarding the causes of urinary schistosomiasis (OR = 0.235, 95% CI = 0.005 1.102, P = 0.066) posed statistically insignificant risk increases for preschoolers contracting urinary schistosomiasis.Conclusions: Urinary schistosomiasis was prevalent among preschool children in Malengachanzi, Nkhotakota District. Contact with infested water puts these children and the general population at risk of infection and reinfection. Inclusion of preschool children in treatment programmes should be considered imperative, along with safe treatment guidelines. To prevent infection, the population in the area should be provided with health education and safe alternative water source

Diversity, distribution and effects on cassava cultivars of Cassava Brown Streak Viruses in Malawi

Cassava brown streak disease (CBSD) has emerged as a major threat to cassava ( Manihot esculenta ) in eastern and southern Africa. CBSD was first reported in Malawi in the 1950s, but little data on the distribution and epidemiology of the disease are available. A diagnostic survey was therefore conducted in Malawi to determine the distribution, incidence and diversity of viruses causing the disease, and to characterize its effects on local cassava cultivars. Diagnostic tests confirmed the presence of cas- sava brown streak viruses (CBSVs) in 90% of leaf samples from symp- tomatic plants. Average CBSD foliar severity was 2.5, although this varied significantly between districts. Both Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (genus Ipomovi- rus , family Potyviridae ) were detected from sampled plants. UCBSV was widespread, whereas CBSV was detected only in the two most northerly districts. The average abundance of the whitefly vector ( Bemisia tabaci ) was 0.4 per plant, a low value that was partly attributable to the fact that the survey was conducted during the cool part of the year known to be unfavourable for B. tabaci whiteflies. Spearman’s correlation analyses showed a positive correlation between CBSD foliar incidence and CBSD severity and between CBSD severity and CBSD stem incidence. Of the 31 cassava varieties encountered, 20 – 20 was most severely affected, whilst Mtutumusi was completely unaffected. Although data from this study do not indicate a significant CBSD deterioration in Malawi, strengthened management efforts are required to reduce the current impact of the disease.Cassava brown streak disease (CBSD) has emerged as a major threat to cassava ( Manihot esculenta ) in eastern and southern Africa. CBSD was first reported in Malawi in the 1950s, but little data on the distribution and epidemiology of the disease are available. A diagnostic survey was therefore conducted in Malawi to determine the distribution, incidence and diversity of viruses causing the disease, and to characterize its effects on local cassava cultivars. Diagnostic tests confirmed the presence of cas- sava brown streak viruses (CBSVs) in 90% of leaf samples from symp- tomatic plants. Average CBSD foliar severity was 2.5, although this varied significantly between districts. Both Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (genus Ipomovi- rus , family Potyviridae ) were detected from sampled plants. UCBSV was widespread, whereas CBSV was detected only in the two most northerly districts. The average abundance of the whitefly vector ( Bemisia tabaci ) was 0.4 per plant, a low value that was partly attributable to the fact that the survey was conducted during the cool part of the year known to be unfavourable for B. tabaci whiteflies. Spearman’s correlation analyses showed a positive correlation between CBSD foliar incidence and CBSD severity and between CBSD severity and CBSD stem incidence. Of the 31 cassava varieties encountered, 20 – 20 was most severely affected, whilst Mtutumusi was completely unaffected. Although data from this study do not indicate a significant CBSD deterioration in Malawi, strengthened management efforts are required to reduce the current impact of the disease.Cassava brown streak disease (CBSD) has emerged as a major threat to cassava ( Manihot esculenta ) in eastern and southern Africa. CBSD was first reported in Malawi in the 1950s, but little data on the distribution and epidemiology of the disease are available. A diagnostic survey was therefore conducted in Malawi to determine the distribution, incidence and diversity of viruses causing the disease, and to characterize its effects on local cassava cultivars. Diagnostic tests confirmed the presence of cas- sava brown streak viruses (CBSVs) in 90% of leaf samples from symp- tomatic plants. Average CBSD foliar severity was 2.5, although this varied significantly between districts. Both Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (genus Ipomovi- rus , family Potyviridae ) were detected from sampled plants. UCBSV was widespread, whereas CBSV was detected only in the two most northerly districts. The average abundance of the whitefly vector ( Bemisia tabaci ) was 0.4 per plant, a low value that was partly attributable to the fact that the survey was conducted during the cool part of the year known to be unfavourable for B. tabaci whiteflies. Spearman’s correlation analyses showed a positive correlation between CBSD foliar incidence and CBSD severity and between CBSD severity and CBSD stem incidence. Of the 31 cassava varieties encountered, 20 – 20 was most severely affected, whilst Mtutumusi was completely unaffected. Although data from this study do not indicate a significant CBSD deterioration in Malawi, strengthened management efforts are required to reduce the current impact of the disease

Exploring Farmers' Knowledge and Approaches for Reducing Post-Harvest Physiological Deterioration of Cassava Roots in Malawi

Cassava utilisation in Malawi is negatively affected by rapid deterioration of fresh roots, primarily caused by postharvest physiological deterioration (PPD). A study was conducted to assess farmers' knowledge and approaches used to minimize losses from PPD. Multi-stage sampling was used to identify districts, Extension Planning Areas (EPA's) and farmers. Data were collected from 519 farmers using a structured questionnaire. Results revealed that PPD (74.0%) was the major post-harvest constraint followed by pests and diseases (62.1%). Farmers had varying knowledge levels on signs and causes of PPD. They were knowledgeable on PPD signs with 91.5% ably identifying PPD through change of pulp colour. The farmers also had moderate knowledge on causes of PPD, citing high temperature (57.6%) and over-staying of roots (56.2%) as main causes of PPD. Key methods for preventing PPD are: storage (43.0%) and piece-meal harvesting (40.4%). Only 2.6% of the farmers exploited varietal difference in dealing with PPD as some varieties (Sauti, Mpuma, Ching'amba, and Kalasa) take three to five days before showing PPD signs. Farmers' knowledge levels and PPD preventive methods could be strengthened through: provision of training on post-harvest handling, improvement in storage and processing technologies; and application of advanced breeding techniques to exploit genetic variation in cassava germplasm

明電舎

種別: 実習報

Characterization of the Production and Dissemination Systems of Nile Tilapia in Some Coastal Communities in Ghana

Aquaculture development has been identified as a key process to meeting the demand for cheap and readily available source of protein. The resultant has been the springing up of cages along the Volta Lake with most farmers producing Nile tilapia. However, the sector faces an array of challenges which needs urgent attention. A study was undertaken to ascertain the production systems and dissemination channel of Nile tilapia among farmers along selected coastal regions in Ghana. A survey of 190 farmers representing the fish farming community in the area was used -these comprised 187 males and 3 females. Pond culture and cage culture were the most common holding facilities used constituting 58.8% and 28.9% respectively. The production of all-male tilapia was popular among farmers and constituted 66.8% of production, while the production of mixed sex tilapia formed 25.8 %. The study revealed that the high prices of fish feed and lack of access to finance were the top ranking financial challenge facing fish farmers in the area corresponding to 73.2% and 51.1% of the response respectively. Other factors such as distance to hatchery and price of fingerling was a significant factor affecting the choice of source of fingerling for stocking (P<0.05) for farmers who used dugout ponds. There was no clearly laid down protocol for dissemination the tilapia. Farmers (16%) who undertook dissemination directly supplied fingerlings and broodstock to other farmers. Investment of capital into tilapia production can improve productivity and profitability