Variation of Proximate Contents in Selected Marine Fish from Tanzanian Coast due to Seasonality and Processing Methods

The effect of seasonality (wet and dry seasons) and processing treatments (frying and boiling) on proximate composition of selected fish species (Alectis ciliaris, Lethrinus harak, Rastrelliger kanagurta and Siganus canaliculatus) from Tanzania marine waters were assessed. The proximate composition of fish was proved to be altered by the fish feeds, salinity, geographical location, seasons and processing methods. Therefore, the fish samples were purposively collected from four selected locations (Tanga, Bagamoyo, Dar es Salaam and Mtwara) and treated as appropriately. Proximate parameters were determined using AOAC standard methods. The proximate contents varied with changing seasons in all the fish species. Crude protein and lipid contents increased in wet season while moisture and ash contents increased in dry season. The effect of changing seasons in proximate contents was significant (p < 0.05) except in ash. Frying process had a significant effect (p < 0.05) on proximate contents in the fish species than boiling process except in ash. The derived model accurately predicted the extent of variation of proximate contents with both dry and wet seasons and processing treatment in particular frying. However, it failed to predict the extent of variation of lipid, crude protein and moisture with boiling treatment. Further research is needed to establish the extent of variations of proximate contents due to other processing methods such as steaming and microwaving

Pesticidal Activity of Wild Mushroom Boletus satanas Lenz Extracts against Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) in Stored Maize Grains

Boletus satanas Lenz (Boletaceae) is a basidiomycete fungus reported to contain monomeric glycoproteins (lectins) which are known to possess insecticidal, larvicidal, ovicidal and anti-nutritional activities. This study was carried out to assess the toxicity, anti-feedant and repellence potential of the crude methanol extract of the mushroom in stored maize grains. Six levels of concentration ranging from 0.05 to 0.5% w/w were used during the assessments. Untreated grains and grains treated with 2% Actellic gold TM dust (0.05% w/w) were used as negative and positive controls, respectively. The experiments were carried out in a completely randomized design with three replicates made for each treatment level and controls. The 0.5% w/w methanol extract exhibited the highest mean mortality of 68.3% and 94.2% inhibition in F1 progeny. Moreover, 89.7% reduction in grain damage and 98.3% pest repellence were observed. These findings render credence to the use of B. satanas as a potential biopesticide by subsistence farmers to preserve grains and corroborate the ongoing IPM strategies.Keywords: Pesticidal activity, Boletus satanas, maize grains, Sitophilus zeamais, grain damage, Tanzani

Factors determining the use of botanical insect pest control methods by small-holder farmers in the Lake Victoria basin, Kenya

A farm survey was conducted in three representative administrative districts of the Lake Victoria Basin (LVB), Kenya to document farmers’ indigenous knowledge and the factors that influence the use of botanicals instead of synthetic insecticides in insect pest management. A total of 65 farm households were randomly sampled using stratified sampling procedure. The maximum likelihood log model was used to determine factors that influence use of botanical and synthetic insect pest control methods (PCM). Results revealed that female gender as household head (HH) and age significantly (P < .001) increased the likelihood of a household using botanical PCM in the field by 0.15 and 0.021, respectively. In storage, female gender and severity of pest infestation significantly (P < .001) increased the probability of a household using botanical insecticide by 0.814 and 0.738, respectively. On the contrary, education of HH (0.342) and ownership of title to land (0.512) significantly (P < .001) reduced the likelihood of using botanical PCM in the field, while traditional rank (0.910) and cash rank (0.744) of the crops reduced the likelihood of using botanical insecticides in the store. With respect to synthetic pesticides, gender (3.407), area cultivated (0.295) and expected yield (5.315) significantly (P < .001) reduced likelihood of their use in the field, while food rank (3.967) reduced the probability of use in storage. In storage, female gender, crop type, food and traditional rank of crops were also the most important factors determining the use of botanical control methods. In conclusion, the study established that female gender, literacy levels, wealth endowments in form of land and old age are key determinants of botanical insecticides use in small-holder farming systems in the LVB, Kenya. It is recommended that the Government of Kenya enacts policies that empower youth and female gender economically in subsistence farming with the aim of improving their educational levels and farming skills to modernize agriculture among the rural communities.Key words: Botanical, Synthetic pesticide, Insects, Pest control method, Determinants, Small-holder farmers

Oral acute toxicity study of selected botanical pesticide plants used by subsistence farmers around the Lake Victoria Basin

A survey carried out around the Lake Victoria region showed evidence that people around this region use plant extracts, parts and powders to protect stored food commodities from insect pests. The widely used plants were identified and selected for biosafety assessments namely: Ocimum gratissimum, Tithonia diversifolia, Eucalyptus saligna, Eucalyptus globulus and Cupressus lusitanica. Wistar mice were acclimatized and divided into groups of six. Each mice group was administered with one extract at different concentrations. The extracts were administered orally and the animals were observed for 24 h. A control group was kept which received only the carrier substance orally. The LD50 values were determined by the use of the graphical method and regression analysis. Oral acute toxicity studies established the LD50 values for essential oils of O. gratissimum, E. saligna and C. lusitanica as 4.570, 2.290, and 3.311 mg/kg, respectively. For ethanol extracts, LD50 values were 12.882, 12.302, 14.996 and 11.481 mg/kg for O. gratissimum, E. globulus, C. lusitanica and T. diversifolia, respectively. For the aqueous extracts, the LD50 of T. diversifolia was found to be 12.302 mg/kg. For E. globulus and C. lusitanica, their aqueous LD50s were beyond 15.000 mg/kg. The oral acute toxicity tests showed weak toxicities for all the plant extracts investigated in the study. The low toxicity levels exhibited by these extracts may be the reason why these plant products have been used by local communities for long without adverse effects. Chronic studies should be carried out to assess whether these extracts have serious effects on experimental animals exposed to them at small doses for a long period of time.Key words: Oral acute toxicity, biopesticide, plant extracts, Lake Victoria Basin

Indigenous knowledge of field insect pests and their management around lake Victoria basin in Uganda

Food security and poverty alleviation has remained the primary agenda in the Eastern Africa regional food policies, and Uganda is no exception. Field pests that attack crops are among the greatest threat to increased food production. The subsistence farmers in the Lake Victoria Basin (LVB) rarely use synthetic pesticides in the field due to the high cost and availability issues. Therefore, some rely on the use of botanical pesticides and other natural methods of pest control. However, this indigenous knowledge (IK) on botanicals has remained largely unexploited with limited regional research and resources committed and these are the premises upon which this ethnobotanical fieldpests management survey was launched and conducted. Most of the respondents were women (59%). The study findings revealed that the major field pests reported by farmers in declining order of importance, included banana weevil, bean fly, cereal stem borers, pod feeders, grain moth, rodents, moths, termites, birds, aphids and cutworms. The anti-pest plants documented included, Capsicum frutescens, Tagetes spp, Nicotiana tabacum, Cypressus spp., Tephrosia vogelii, Azadirachta indica, Musa spp, Moringa oleifera, Tithonia diversifolia, Lantana camara, Phytollacca dodecandra, Vernonia amygdalina, Aloe spp., Eucalyptus spp., Cannabis sativa, Cofea species and Carica papaya. The study has demonstrated that usage of botanical pesticides in field pest management is normal around Lake Victoria basin for the subsistence farmers since all the 117 respondents had ever tried or used botanical pesticides. We recommend more specialized studies in the usage of the plant-based pesticides to ensure safety and effectiveness that will enhance food security and environment protection. In addition, appropriate recommendations generated on the issues investigated will be advanced as leads for further research, extension and regional industrial endeavors in the LVB.Key words: Indigenous knowledge, field pests, pesticide plants, Uganda, Lake Victoria Basin

Larvicidal, antimicrobial and brine shrimp activities of extracts from Cissampelos mucronata and Tephrosia villosa from coast region, Tanzania

<p>Abstract</p> <p>Background</p> <p>The leaves and roots of <it>Cissampelos mucronata </it>A. Rich (Menispermaceae) are widely used in the tropics and subtropics to manage various ailments such as gastro-intestinal complaints, menstrual problems, venereal diseases and malaria. In the Coast region, Tanzania, roots are used to treat wounds due to extraction of jigger. Leaves of <it>Tephrosia villosa </it>(L) Pers (Leguminosae) are reported to be used in the treatment of diabetes mellitus in India. In this study, extracts from the roots and aerial parts of <it>C. mucronata </it>and extracts from leaves, fruits, twigs and roots of <it>T. villosa </it>were evaluated for larvicidal activity, brine shrimps toxicity and antimicrobial activity.</p> <p>Methods</p> <p>Powdered materials from <it>C. mucronata </it>were extracted sequentially by dichloromethane followed by ethanol while materials from <it>T.villosa </it>were extracted by ethanol only. The extracts obtained were evaluated for larvicidal activity using <it>Culex quinquefasciatus </it>Say larvae, cytotoxicity using brine shrimp larvae and antimicrobial activity using bacteria and fungi.</p> <p>Results</p> <p>Extracts from aerial parts of <it>C. Mucronata </it>exhibited antibacterial activity against <it>Staphylococcus aureus</it>, <it>Escherichia coli</it>, <it>Pseudomonas aeruginosa</it>, <it>Salmonella typhi</it>, <it>Vibrio cholera</it>, <it>Bacillus anthracis</it>, <it>Streptococcus faecalis </it>and antifungal activity against <it>Candida albicans </it>and <it>Cryptococcus neoformans</it>. They exhibited very low toxicity to brine shrimps and had no larvicidal activity. The root extracts exhibited good larvicidal activity but weak antimicrobial activity. The root dichloromethane extracts from <it>C. mucronata </it>was found to be more toxic with an LC₅₀value of 59.608 μg/mL while ethanolic extracts from root were not toxic with LC₅₀>100 μg/mL). Ethanol extracts from fruits and roots of <it>T. villosa </it>were found to be very toxic with LC₅₀values of 9.690 μg/mL and 4.511 μg/mL, respectively, while, ethanol extracts from leaves and twigs of <it>T. villosa </it>were found to be non toxic (LC₅₀>100 μg/mL).</p> <p>Conclusion</p> <p>These results support the use of <it>C. mucronata </it>in traditional medicine for treatment of wounds. Extracts of <it>C. mucronata </it>have potential to yield active antimicrobial and larvicidal compounds. The high brine shrimp toxicity of <it>T. villosa </it>corroborates with literature reports that the plant is toxic to both livestock and fish. The results further suggest that <it>T. villosa </it>extracts have potential to yield larvicidal and possibly cytotoxic compounds. Further studies to investigate the bioactive compounds responsible for the observed biological effects are suggested.</p

Environmental Health Risks Due to Anthropogenic Metals in Mtoni Estuary Ecosystem and its Environs, Tanzania

Mangrove sediment samples from Kizinga and Mzinga creeks of Mtoni estuary were analysed for metals (Al, Fe, Mn, Cr Ni, Cu, Zn, As, Sr, Cd and Pb) to determine their current levels and their anthropogenic impact in a tropical estuarine environment. Standard sampling techniques were used. Samples were digested using a CEM Microwave Accelerated Reaction System (MARS) and analysis was carried out using a High Resolution Inductively Coupled Plasma Mass Spectrometer (HR-ICP-MS). Sandy particles were dominant, with < 6% of OM in estuary and < 9% in tributaries. Metal levels showed neither distinct depth gradient nor variation between seasons. A clear gradient from upstream of Kizinga and Mzinga rivers to estuarine mouth was observed. Pearson correlation matrix, Principal component analysis (PCA) and Enrichment factors (EF) indicated that most metals in Mtoni estuary probably originated from anthropogenic activities except Sr that was probably derived from natural origin. Levels of anthropogenic pollutants are indicative of human induced environmental change and have repercussions on environmental and human health as well as future status of estuary

Pesticidal Activity of Wild Mushroom Amanita muscaria (L) Extracts against Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) in Stored Maize Grains

The toxicity, antifeedant activity and repellency of the crude methanol extract of the wild mushroom Amanita muscaria on Sitophilus zeamais in stored maize grains was determined by assessments, carried out between the extracts concentration of 0.05 and 0.5% w/w. Nontreated and treated grains with 2% Actellic gold TM 2% dust (0.05% w/w) were used as negative and positive controls, respectively. Three replicates were made for each treatment and experiments were conducted in a completely randomized design. The methanol extract at 0.5% w/w concentration showed highest toxicity 21 days after treatment killing 61.7% of the pest. Interestingly, 68.6% inhibition of F1 progeny was observed at 0.5% w/w 42 days after treatment whereas the reduction in grain damage was up to 86.0% compared to the negative control. The extract demonstrated a pest repellency of up to 96.7% after 24 hours of exposure. The findings were promising for use of A. muscaria as a biopesticide for maize grains storage towards supporting the ongoing IPM strategies. The study provides a baseline data that needs to be complimented by doing more research on the active compounds in the mushroom as well as improving the synthetic industry based on the fact that most of the species are endemic