Browsing by Author "Kitojo, D. H."

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The effect of clay on the persistence of BTi toxicity against mosquito larvae in Morogoro, Tanzania IA
(2001) Kilonzo, B. S.; Madoffe, S. S.; Maliondo, S. M. S.; Msanya, B. M.; Mabagalla, R.; Kitojo, D. H.
Laboratory colonies of Anopheles gambiae and Culex quinquefasciatus were reared from parental larvae obtained from the Ifakara Health Research Centre and septic tanks ill Morogoro Municipality respectively. Water ponds (1M3 ) were constructed at selected sites and left open for mosquitoes to breed ill freely. Various concentrations of Bti crystals were-mixed with varying concentrations of clay and tested against third instar larvae of each species at various periods of time post-preparation. A total of 60 larvae (20 x 3) were exposed to each mixture in the laboratory, and each- experiment was replicated four times. Mortality rates were recorded after 241t. exposure. The observations revealed that for every concentration of Bti crystals used, the toxicity on both species of mosquitoes was less persistent in crystal/clay mixtures than in crystals alone. It was also shown that such persistence was much less in mixtures containing large concentrations of clay (5mg/ml) titan in those containing low concentrations (0.05 - 0.5 mg/ml) of clay. It wasfurther observed th at the toxicity against Culex and Anopheles larvae was more persistent in mixtures containing higher concentrations of Bti crystals (0.12 - 0.3 ug/ml) titan ill those containing low concentrations (0.03 - 0.06 ug/ml) of the toxin. Furthermore, it was observed that C. quinquefasciatus larvae succumbed to Bti crystal/clay mixtures for longer periods titan A. gambiae larvae. It was generally concluded that clays have 11 negative impact on the persistence of Bti toxicity against mosquito larvae and th at such impact is more significant in mixtures containing large concentrations clay. It was also concluded that despite the environmental friendliness of Bti, its applicability by communities is limited in view of its short persistence when it is adsorbed to tropical soils which are found in most natural mosquito breeding sites.
Potentials of lesser known and lesser utilized indigenous agroforestry timbers in Kilosa District, Morogoro Tanzania
(International Journal of Education and Research, 2015-11-12) Makonda, F. B. S.; Augustino, S.; Gillah, P. R.; Ishengoma, R. C.; Kitojo, D. H.; Ruffo, C.; Eriksen, S.; Msanga, H. P.
The paper presents baseline results of gathered important information for inference in establishing optimal production and utilization of Lesser-known (LK) and Lesser-utilized (LU) indigenous agroforestry timber species (IAGTS) in improving incomes of rural communities in Kilosa District. The main key questions were: what are the characteristics of the sites for establishing LK and LU IAGTS; who are the main actors in establishing LK and LU IAGTS; what are LK and LU IAGTS and other species for establishment in the study area and what are the strengths, weaknesses, opportunities and threats for establishing LK and LU IAGTS in the study area. Data collection was participatory, involving key stakeholders, participants’ observations and literature surveys. A total of eight villages were identified as potential sites for nursery establishment with seven main actors’ mostly local communities engaged in tree planting activities under associations. Five priority LK and LU IAGTS were identified and selected for nursery establishment. These were: Lonchocarpus capassa (Mfumbili), Sclerocarya birrea (Mng’ongo), Vitex doniana (Mfudu), Pseudolachnostylis maprouneifolia (Msolo) and Combretum zeyheri (Mlama mweupe). The strengths and opportunities favouring the establishment of LK and LU IAGTS nurseries were identified, with a few weaknesses and threats which needed to be worked upon.
Properties of celtiz zenkeri engel: a lesser-known timber species from Kilindi District, Tanzania
(Tanzania Journal of Forestry and Nature Conservation, 2009) Gillah, P. R.; Makonda, F. B. S; Kitojo, D. H.; Ishengoma, R. C.; Khalid, S.
This study was conducted to provide some of the basic physical and strength properties of wood of Celtis zenkeri Engel. which is among the lesser-known and lesser-utilized timber species from Tanzania. Celtis zenkeri belonging to the family Ulmaceae is currently being harvested for wood fuel and building poles thus being under-valued and placed in class V timbers since the basic properties of its wood are not yet known. The objective of this study was therefore, to determine and assess some of the basic physical and mechanical properties of C. zenkeri specifically colour, texture, basic density, Static bending (Modulus of Flasticity, Modulus of Rupture, Work to maximum Load and Total work), Compression parallel to grain, Shear and Cleavage stress. Relationships between basic density and the mechanical properties were also assessed. Data for this study were collected from three mature and defect free sample trees objectively selected from Kilindi district in Tanga region. Each sample tree produced three logs; from bottom, middle and upper part of the bole. Test specimens were extracted from the samples and by using standard methods, the physical and mechanical properties were determined. The following are the wood strength properties obtained for C. zenkeri. Basic density (655 kg m-3) and Total Work (21,916 N mm-2), Modules of rapture (198 N mm-2), Work to maximum load (0.360 N mm-3) and Total Work (0.598 N mm-2). Others are; Cleavage strength (24.56 N mm-width), compression strength (97.1 N mm-2) and Shear strength (28.7 N mm-1) Celtis zenkeri wood was found to have desirable values to be used for hand tools, joinery, building, plywood, artificial limbs and flooring furniture.
Properties of nesogordonia holtzh subsp hotzii (Moss) capuron: a lesser known timber species from Kilindi District, Tanzania
(Tanzania Journal of Forestry and Nature Conservation, 2009) Gillah, P. R.; Makonda, F. B. S.; Kitojo, D. H.; Ishengoma, R. C.
Nesogordonia holtzii subsp holtzii (Moss) Capuron is a lesser-known timber species belonging to the family Sterculiaceae. The species is distributed in the eastern tropical Africa in association with other tree species as Newtonia buchananii, Albizia versicolor, Allanblackia stuhlmanii, Antiaris toxicaria and Sterculia appendiculata. Currently it is harvested for fuelwood and building poles thus being under-valued, Due to its wood technical properties not known to users it is placed in royalty fee class V timbers. The objective of this study was therefore to determine and assess some basic physical and mechanical properties of N. holtzii. Compare the determined strength properties of N. holtzii with those from well known tree species. Use different combinations of the properties of N. holtzii obtained to assign suitable end uses and promote it for its utilization. Three mature sample trees free from visible defects were selected randomly. Each tree was sampled to produced three logs. Test specimens were extracted from the sample logs using the method by Larvers (1969). Physical and strength properties determination was carried out according to the procedure described in ISO 3131(1975) ISO3133 (1975) BS 373(1957, 1976) Larvers (1969) and Panshin and de Zeeuw (1970). The results showed that N. holtzii was found to have yellow timber that turns reddish brown on seasoning and the wood is fine textured. The average basic density is 593 kg m-3 Modulus of Elasticity 7,606 N/mm-3, Modulus of Rupture 81 N/mm-2, Work to Maximum Load 0.098 N mm-3, Total Work 0.196 N mm-3, Compression Stress 48.83 N mm- 2, Shear Stress 11.40 N mm-2 and Cleavage Strength 24.98 N mm-1. These properties are within the acceptable range for the building and furniture industry. As many traditional timbers become scarcer, the timber of Nesogordonia holtzii should be promoted and is recommended as a substitute for Afzelia quanzensis, Pterocarpus angolensis and Newtonia buchananii. The resemblance in colour allows these timber species to be sold in one group.
Some physical and mechanical properties of Uapaca Kirkiana, a lesser-known timber species from Tanzania
(Tanzania Journal of Forestry and Nature Conservation, 2007) Gillah, P. R.; Makonda, F. B.; Ishengoma, R. C.; Kadala, B.; Kitojo, D. H.
This study was carried out to determine some physical and mechanical properties of Uapaca kirkiana a lesser known timber species growing in public land near Iyondo Catchment Forest Reserve, Kilombero District, Morogoro, Tanzania. A total of 3 trees were used in the study. Preparation of test samples and laboratory procedure to determine some physical and mechanical properties followed standard methods. Analysis of variance was used to determine the variation between and within trees and regression analysis was used to determine relationship between wood basic density and mechanical properties. The results showed that Uapaca kirkiana has whitish sapwood and dark brown heartwood, with a mean basic density of 518.14 kg/m3. The properties of Uapaca kirkiana were as follows: modulus of elasticity (7185.69 N/mm2), modulus of rupture (59.7 N/mm2), work to maximum load (0.06 mmN/mm3), total work to failure (0.07 mmN/mm3), shear strength parallel to the grain (11.86 N/mm2), compression strength parallel to the grain (34.4 N/mm2) and cleavage strength (20.21 N/mm width). On axial direction, the modulus of elasticity, total work to failure, compression strength parallel to grain and cleavage strength were directly proportional to its basic density while modulus of rupture, work to maximum load and shear strength parallel to the grain were inversely proportional implying that Uapaca kirkiana is suitable for activities, which require high modulus of elasticity, total work to failure, compression strength parallel to the grain and cleavage strength. On radial direction modulus of elasticity, modulus of rupture, work to maximum load, compression parallel to the grain and cleavage strength were directly proportional to basic density while shear parallel to the grain was inversely proportional to basic density. Compared to Khaya anthotheca, the timber species found in the same location and market; it was found that the timber of Uapaca kirkiana had modulus of rupture and compression parallel to the grain far lower than those of Khaya anthotheca, while the work to maximum load, total work to failure, shear strength parallel to grain and modulus of elasticity were almost the same. Due to the similarity in some of their physical and mechanical properties, the wood of Uapaca kirkiana may berecommended to substitute Khaya anthotheca in wood works that require medium density wood like in decoration where colour is considered an important aspect for appearance and in cabinet, panel and furniture making though it is not adequate in high-class strength joinery.
Some physical and strength properties of lesser known aphloia theiformis timber from Lushoto Tanga, Tanzania
(Tanzania Journal of Forestry and Nature Conservation, 2008-07-14) Gillah, P. R.; Makonda, F. B. S.; Hussein, I.; Augustino, S.; Kitojo, D. H.
Some physical and strength properties of lesser known Aphloia theiformis timber grown in and around Magamba Forest Reserve, Lushoto district, Tanga region were determined. A total of three sample trees were randomly selected and felled for this study. Test samples for moisture content, basic density and Strength properties determination were prepared and tested according to Lavers (1969), BS 373 (1957), ISO 3130 (1975), ISO 3131 (1975), ISO 3133 (1975) and ISO 3349 (1975). It was observed that Aphloia theiformis timber has a sapwood and heartwood colour ranging from creamcoloured to whitish pink resembling that of Grevillea robusta. The average basic density was 519 kg/m3 with a standard deviation of 4.2 which can be classified as medium-density timber. The basic density showed a slight decrease from butt end to top end. Regarding strength properties, Aphloia theiformis timber had a mean modulus of rupture of about 55.8 N/mm2 and modulus of elasticity of about 3854 N/mm2. The work to the maximum load was about 0.06mmN mm-3, while total work averaged 0.08mmN mm-3. The compression and shear parallel to the grain were 37.4 and 12.6N mm-2 respectively. Furthermore, all strength properties of Aphloia theiformis were positively correlated with basic density. The properties of this timber were also comparable to properties of Grevilea robusta and are always rated the same by timber dealers. While Aphloia theiformis had higher tearing strength than Grevillea robusta, the modulus of rupture and compression parallel to the grain values were comparable. Aphloia theiformis can therefore substitute Grevilea robusta in many areas of its application.