https://www.ajol.info/index.php/ejst/issue/feed Ethiopian Journal of Science and Technology 2020-11-03T14:31:41+00:00 Dr Melaku Wale editorejst@bdu.edu.et Open Journal Systems <p>The <em>Ethiopian Journal of Science and Technology</em> (EJST) publishes high quality original&nbsp;&nbsp; research articles, reviews, short communications, and feature articles on basic and applied aspects of science, technology, agriculture, health and other related fields.</p> <p>Other websites associated with this journal:&nbsp;<a title="http://www.bdu.edu.et/page/ethiopian-journal-of-science-and-technology" href="http://www.bdu.edu.et/page/ethiopian-journal-of-science-and-technology" target="_blank" rel="noopener">http://www.bdu.edu.et/page/ethiopian-journal-of-science-and-technology</a></p> https://www.ajol.info/index.php/ejst/article/view/201236 Assessment of quality and suitability of groundwater resources for industrial and irrigation purposes, Dire Dawa, Ethiopia 2020-11-03T08:42:42+00:00 Girmaye Haile Gebremikael grhaile@gmail.com Aman Hussien Dawod grhaile@gmail.com <p>The groundwater demand of Dire Dawa has increased recently due to the expansion of irrigation and the industrial sector in the city. Groundwater used for irrigation and industry was studied. Eighty-two samples were used to analyze physicochemical using different indices like Langelier index (LSI), Ryznar index (RSI), Aggressive index (AI) and Larson-Skold index (LRI). Parameters of Sodium Absorption Ratio (SAR), Residual Sodium Carbonate (RSC), Dissolved Sodium (%Na), Magnesium hazard (%Mg) statistical and spatial distributions were analyzed and programmed with Excel, Arc GIS, and Diagrams software. Results showed that pH, Mg<sup>2+</sup>, Cl<sup>-</sup> were found to be within the limit for industrial use. The groundwater corrosion indices mean values of LSI, RSI, AI, and LRI obtained were 0.29 ± 0.28, 6.4 ± 0.5, 12.20 ± 0.24 and 1.4±1.57, respectively. LSI, RSI results indicated a moderate scale-forming tendency of the groundwater. AI values were within low to no corrosion rates in all zones. Because of Cl<sup>-</sup> and SO<sub>4</sub><sup>2-</sup>, LSI showed some localized corrosion properties at kebele 01 and 09. Parameters like pH, Conductivity, Na<sup>+</sup>, HCO<sub>3</sub><sup>- </sup>and Cl<sup>-</sup> ion were within permissible limits for irrigation. The irrigation indices (meq/l); SAR, RCS, Na% and Mg Hazard were calculated to be 1.33, -2.17, 21.5%, 45%, respectively. The EC was within the permissible limit but was significant. The low values of SAR, RCS, Na% indicated that the groundwater can cause lower alkalization (Sodium hazard) effect. In conclusion, all the parameters of the groundwater sources were categorized as good for irrigation. However, corrosion indices elaborated the groundwater scaling problems and may also be aggravated with temperature and heat-related industrial equipment.</p> Copyright (c) https://www.ajol.info/index.php/ejst/article/view/201238 Physico-chemical and biological evaluation of Blue Nile River at Lake Tana, Ethiopia, in relation to discharge of tannery effluent 2020-11-03T14:31:41+00:00 Mekdes Hone mekdeshone@gmail.com Getachew Beneberu mekdeshone@gmail.com <p>Pollution of aquatic ecosystems with waste-water coming from tanneries is a serious challenge worldwide. The purpose of this study was to assess the water quality of Blue Nile River at a tannery in Bahir Dar, Ethiopia, using physicochemical and biological attributes. Four sampling sites were selected along the river based on the degree of degradation and major land-use types. Phyisco-chemical data, water samples, and chironomid larvae were collected monthly from March-May, 2016. Two liters of water were collected from each site and stored in the icebox and transported to Bahir Dar University. Water samples were analyzed for nutrients following standard procedures.&nbsp; Chironomid larvae were collected using a D- Frame net of 500 µm mesh size. One-way ANOVA was used to compare variations in all measured parameters among the sampling sites. Low dissolved oxygen (2.8 mg/l) was recorded at the site where the tannery meets the river. Moreover, the concentration of soluble reactive phosphorus, SRP (25.5±14.3 μg/l) and conductivity (1907.3±39.5 µS/cm) were low in the most upstream site of the river. A total of six Chironomid genera belonging to the subfamilies Chironominae and Tanypodinae were identified.&nbsp; The genus <em>Chironomus</em> dominated the impacted sites that had low dissolved oxygen levels. The other five genera were not found in those impacted sites. The result of this study indicated that the tannery effluent had impact on chironomid distribution as well as on river water quality.</p> 2020-11-03T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/ejst/article/view/201230 Management of Blue Gum Chalcid (Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) infestation on different species of Eucalyptus trees in Kalu district, Eastern Amhara, Ethiopia 2020-11-03T07:58:37+00:00 Tigabu Redae Alle redtiges1980@gmail.com Adane Tesfaye Lema redtiges1980@gmail.com Seid Muhie Dawud redtiges1980@gmail.com <p>The recently introduced chalcid pest known as the Blue Gum Chalcid (BGC) (<em>L. invasa</em>) is currently one of the major insect pests of <em>Eucalyptus</em> tree species in Ethiopia. A research was conducted in Kalu district, South Wollo, Eastern Amhara, Ethiopia, the main objective of which was to evaluate the effectiveness of synthetic insecticides, hoeing and water showering options against BGC. Two parallel experiments were conducted in the nursery and in the field. <em>Eucalyptus camaldulensis, E. saligna, E. viminalis, E. citrodora </em>and<em> E. globulus</em> were considered in the nursery at Chorisa. One to three-year old <em>E. camaldulensis</em> plantations were considered at Tikuro plantation site. At the nursery, seven treatments and at the field 10 treatments were tested in a Randomized Complete Block Design (RCBD) with three replications from January to February 2019, where treatments were applied 3 times at 15-day intervals. Results from the 1-year old plantation revealed that application of Dimethoate 40%, Carbofuran 3G and Dimethoate 40% + hoeing followed by Carbofuran 3G + hoeing and Thiamethoxam 25WG were effective in checking the BGC insect pest infestation. In the 3-year old plantation<em>, </em>Carbofuran 3G significantly reduced the infestation followed by Dimethoate 40%. At the nursery, Dimethoate 40% and Carbofuran 3G reduced the infestation followed by Carbofuran 3G + Dimethoate 40% and thiamethoxam 25WG. Water showering and hoeing did not reduce BGC infestation in all cases at the field plantations. Treatments that received synthetic insecticides and hoeing had low infestation, the reason for which was the insecticide rather than the hoeing, because the hoeing alone didn’t differ from the control. Application of Dimethoate 40% and Carbofuran 3G with hoeing and weeding activities were recommended to manage and limit BGC insect pest infestations.</p> 2020-10-25T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/ejst/article/view/201233 Impact of bendiocarb 80% WP indoor residual spraying on insecticide resistance status of Anopheles arabiensis 2020-11-03T08:10:58+00:00 Alemayehu Abate abate_alemayehu@yahoo.com Emana Getu abate_alemayehu@yahoo.com Melaku Wale abate_alemayehu@yahoo.com Mamuye Hadis abate_alemayehu@yahoo.com Wubegzier Mekonen abate_alemayehu@yahoo.com <p><strong>Long term and wide use of indoor residual sprays augments the selection of insecticide resistance genes. The development of insecticide resistance in an insect population depends up on the volume and frequency of sprays against them and the inherent characteristics of the insect species. However, despite its use for decades, the effect of residual sprays on the status of insecticide resistance of malaria vectors is unknown in Ethiopia. The objective of this study was to assess the effect of </strong><strong>bendiocarb 80% WP</strong><strong> indoor residual spraying on insecticide resistance status of <em>An. arabiensis</em> in Bahir Dar Zuria District, Northwest Ethiopia. Susceptibility of <em>An. arabiensis </em>was examined against different insecticides using 2-3-day old female mosquitoes following WHO insecticide susceptibility test procedures. Test results were calculated according to WHO bioassay test protocol. Chi-square test was used to determine the significance level of differences between years and study sites. Susceptibility of <em>An. arabiensis</em> to fenitrothion, pirimiphosmethyl and propoxur was 100% in both study villages for three successive years. Resistance to bendiocarb was suspected after two years (2015) in Andassa, but not in Tikurit. Mortality and knock down due to DDT significantly increased from 2013 to 2015 at Tikurit (knock down: χ<sup>2</sup> = 117.9, <em>P&lt;.0001</em> and mortality:&nbsp; χ<sup>2</sup> = 66.3, <em>P&lt;.0001</em>; due to deltamethrin, knock down: χ<sup>2</sup> = 7.3, <em>P=.004</em> and mortality: χ<sup>2</sup> = 37.8, <em>P&lt;.0001</em>). The same was true at Andassa (due to DDT, knock down: χ<sup>2</sup> = 198.7, <em>P&lt;.0001</em> and mortality:&nbsp; χ<sup>2</sup> = 82.9, <em>P&lt;.0001</em>; due to deltamethrin, knock down: χ<sup>2</sup> = 26.1, <em>P&lt;.0001</em> and mortality: χ<sup>2</sup> = 48.2, <em>P&lt;.0001</em>). Bendiocarb was effective against the <em>An. arabiensis</em> for two years under bendiocarb IRS operation so that alternative insecticides with different mode of action should be replaced every two to three years to prolong its efficacy.</strong></p> Copyright (c) https://www.ajol.info/index.php/ejst/article/view/201235 Biological monitoring of freshwater ecosystem health in Ethiopia: A review of current efforts, challenges, and future developments 2020-11-03T08:23:27+00:00 Workiye Worie Assefa workiye2008@gmail.com Getachew Beneberu workiye2008@gmail.com Baye Sitotaw workiye2008@gmail.com Ayalew Wondie workiye2008@gmail.com <p>Aquatic resources are increasingly stressed primarily due to anthropogenic activities in Ethiopia. These anthropogenic stresses altered ecological integrities and compromised ecosystem services that could otherwise support the livelihoods of millions of people. Evidence-based management of the degradation of aquatic ecosystems requires quantifying ecologically significant changes and discriminating among impact levels and types. Apart from physico-chemistry, monitoring of aquatic ecosystems using biological organisms is progressing well in recent times both in the tropics and temperate regions. The majority of studies so far focused on macroinvertebrates and to a lesser extent on diatoms. Though the method is given less attention, individual initiatives have been increasing over time especially in developing countries, including Ethiopia. This paper reviews current efforts undertaken and major challenges facing the use of bioindicators in aquatic ecosystems as biological monitoring tools. The possible application of biomonitoring and its importance for Ethiopian aquatic ecosystems is also discussed and future improvements suggested.</p> Copyright (c)