Background: The life style and biology of dung beetles offer a significant opportunity for innovation in biofuel production. The larvae of the African dung beetle, Euoniticellus intermedius, feed solely on cow dung, eating and digesting the fibre while adults live on juices found in fresh dung. The larval gut system consists of a small, almost unrecognizable foregut and two distinct chambers; the midgut and hindgut. It is clear that these two chambers are the centres in which the dung material whose composition includes cellulose is processed. The goal of this study was to assess the cellulolytic activities of cultured gut micro-flora derived from E. intermedius, (Coleoptera: Scarabaeida). Method: Late second to third instar stage E. intermedius larvae were dissected and the isolated gut micro-flora consortia aerobically cultured in media containing cellulose (filter paper) as the sole carbon source. Genomic DNA isolation was done on the gut consortia cultures after 10 days of culturing, using the ZR Fungal/Bacterial DNA MiniPrep kit (Zymo Research, USA). A complete and unbiased primary cosmid library was then constructed from the isolated genomic DNA using a cloning ready, pWEB-TNC™ Cosmid Cloning kit (EPICENTRE Biotechnologies, USA). The primary cosmid library clones were screened for endo-glucanase and cellobiohydrolase activities using Carboxymethyl Cellulose (CMC) and 4-Methylumbelliferyl-β-D-Cellobioside (MUC) plate assays respectively. Results: Results indicate that a total of 7 colonies out of 160 screened colonies showed positive CMC and MUC activities. Conclusion: This proves that E. intermedius is a potential source of cellulolytic micro-organisms and enzymes that can be used for cellulose derived biofuel production.
The traditional way of assessing water quality of water bodies is through measurement of biological, physical and chemical parameters. However, such assessments only reflect the concentration of pollutants at the time of sampling not periodic pollution events. The goal of the study was to evaluate the river health using the macro-invertebrates that are found within the Mucheke and Shagashe rivers of Masvingo City as water quality monitors. The South African Scoring System (SASS 5) was used to score using the sensitivity of macro-invertebrates to levels of pollution in the two river systems. The data collection process was carried in April 2017 at four sampling sites using the kick sampling method and results validated by testing the physical, chemical and biological characteristics of the water and comparing them with the macro-invertebrates score. Results showed that the mean sensitivity score of macro-invertebrates showed variations depending on the selected site. Sample sites B2 and A2 downstream of the two river systems show high levels pollution tolerant macro-invertebrates as compared to sites A1 and B1 that are on the upper course and have more of pollution sensitive macro-invertebrates. On validation, to a large extent the levels of pollution indicated by macro-invertebrates were found to be congruent to the levels of pollution indicated by the physical, chemical and biological parameters. The research concludes that the presence of specific types of macro-invertebrates can be used to assess the levels of pollution in Mucheke and Shagashe rivers of Masvingo City.
Farmers' indigenous knowledge of storage insect pests and management practices in stored grain protection against insect pests are critical for sustainable food security in the smallholder sector in Zimbabwe. A survey was conducted among 48 and 51 maize farmers in wards 9 and 10 Bikita district respectively, to evaluate their knowledge, attitudes and traditional maize storage management practices against storage insect pests. The selected farmers grew maize and a variety of vegetables for subsistence. Problem storage pests listed in order of prevalence were maize weevil (Sitophilus zeamais) 49%, lesser grain borer (Rhizopertha dominica) and maize weevil (Sitophilus zeamais) complex 25.5%, lesser grain borer (Rhizopertha dominica) 17.7% and larger grain borer (Prostephanus truncatus) 7.3%. The commonly used botanical pesticides in the two wards were gumtree (Eucalyptus spp) (24.6%), tamboti (Spirostachys africana) (7.2%), lilac tree (Melia azedarach) (4.1%), sunflower (Helianthus annuus) ash (5.1%), cow dung (3.1%), lemon bush (Lippia javanica) (2%), murwiti (Rapanea melanophloeos) (1%), sweet basil (Ocimum basilicum) (1%) and finger millet (Eleucine coracana) chuff (1%),wood ash (4.1%) and mixtures of the above mentioned botanicals (4.5%). The botanicals are mixed with maize grain before storage either in sealed hessian bags or as loose grain placed in the granary plastered with cow dung. The use of botanicals was more prevalent in Ward 10 (100%) than ward 9 (14.7%). Farmers resort to the use of cheap and locally available botanicals when there is no money to buy synthetic insecticides. There is an urgent need for laboratory evaluation of the efficacy, chemical composition and mode of action in order to come up with dosage guidelines of these ethnobotanicals for the resource poor smallholder farmers.
This study assessed the capabilities of the dung beetle, Euoniticellus intermedius (Coleoptera: Scarabaeida), larva gut consortia in degrading cellulose that can serve as glucose source for biofuels production. A total of 144 live dung beetles were randomly collected from a dairy farm and bred in a temperature controlled insect rearing room. On reaching the late second to third instar stage, dung beetle larvae were harvested, dissected and the gut micro-flora were cultured in medium containing cellulose as sole carbon source. Microbial growth (total protein concentration) and cellulose degradation activity (reducing sugars concentration) in the cellulose cultures were monitored successively for 15 days. Statistical analysis showed that there was significant microbial growth, but no significant increase in reducing sugar levels. Despite the lack of increase in reducing sugar levels, it was concluded that the dung beetle larva gut has micro-flora with cellulose degrading capabilities that allowed it to grow and survive in the cellulose minimal medium.
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