Browsing by Author "Tekie, Habte"

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    The Ecology of the Anthropophilic Anopheles Mosquitoes in the Ghibe Horticulture Development Farm
    (Addis Ababa,University, 1989-06) Tekie, Habte; Gemetchu, Teferi (PhD)
    Ecological studies on the Anthropophilic Anopheles Mosguitoes of Ghibe From Were Conducted Between April, 1987 and March, 1988 (12 months), and Between November, 1988 and February, 1989 (4 months), it was found that malaria is endemic in the area.
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    Entomological Impact of Combined and Separate Use of Indoor Residual Spraying and Long-Lasting Insecticidal Nets for Malaria Prevention in Adami Tullu District, South-Central Ethiopia
    (Addis Ababa University, 2016-02-03) Kenea, Oljira; Tekie, Habte
    Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the key frontline malaria prevention interventions in Ethiopia. Both target Anopheles arabiensis, the sole primary malaria vector. Universal coverage of both interventions has been promoted and there is a growing demand in combination of interventions for malaria control and elimination. However, available evidence is contradictory wether the combined intervention is better than either IRS or LLINs alone. To investigate whether IRS and LLINs combination provides added protective impact on An. arabiensis compared to either IRS or LLINs alone, a cluster randomized controlled trial was carried out in Adami Tullu district, south-central Ethiopia. Villages were randomly allocated to four study arms: IRS+LLINs, IRS, LLINs, and control. All households in the IRS+LLINs and LLINs arms were provided with LLINs (PermaNet 2.0) free of charge. Households in the IRS+LLINs and IRS arms were applied with propoxur before the main malaria transmission season in 2014 and 2015. Adult mosquitoes were collected in randomly selected villages in each arm using CDC light trap catch (LTC) set close to a sleeping person, pyrethrum spray catch (PSC), and artificial pit shelter (PIT), for measuring host-seeking density (HSD), indoor resting density (IRD), and outdoor resting density (ORD) of the anophelines. Human landing catch (HLC) was performed in selected villages to monitor the impact of the interventions on local mosquito biting behaviours (biting location, time and host preference). Collected anophelines were identified to species by use of standard morphological keys and additional use of molecular methods to separate sibling species of the An. gambiae complex. Enzyme-linked immunosorbent assay (ELISA) was used to detect malaria infections in mosquitoes and the sources of mosquito blood meals. Mean densities were compared using incidence rate ratio (IRR) calculated by negative binomial regression. Parity rate (percentage of xxii parous females) was also determined by ovarial dissection. Human blood index (HBI) was expressed as the proportion of mosquitoes with human blood divided by the total number of blood-fed mosquitoes tested. A total of 1786 female anophelines of four species (An. arabiensis, An. pharoensis, An. ziemanni and An. funestus s.l.) were collected over two transmission seasons during the intervention period (2014-2015). Anopheles numbers were highest in the control arm (41.3% of total) followed by LLINs (25.4%), IRS (18.0%), and IRS+LLINs (15.8%). In most of the vector parameters estimated, the impact of IRS and LLINs combined and separate interventions were significantly higher in communities that recieved the interventions (in experimental groups) compared with untreated communities (control group). The mean HSD of An. arabiensis in the IRS+LLINs arm was similar to the IRS arm (0.03 vs. 0.03/ house/LTC/night) but lower than the LLINs arm (0.03 vs. 0.10/house/LTC/night, p=0.07) and so was the difference in IRD and ORD between the IRS+LLINs compared to the IRS arm. However, both IRD and ORD of An. arabiensis were higher in LLINs compared to IRS+LLINs (p < 0.001 for indoors). Parity rate of An. arabiensis were similar among the intervention arms. None of the 1786 samples of four species tested by ELISA was positive for P. falciparum and P. vivax CSP infection in all of the study arms. Anopheles arabiensis preferred mainly bovine and human hosts for blood meal sources with high HBI in the LLIN alone. Indoor resting habit of An. arabiensis was less impacted by LLINs alone intervention compared to IRS + LLINs or IRS alone. In conclusion, the IRS+LLINs and the IRS alone each was similarly most effective against An. arabiensis as compared to the LLINs alone. The IRS+LLINs provided added impact on An. arabiensis compared to LLINs alone. The LLINs alone had poor impact on densities and human biting rates of An. arabiensis in this study setting.
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    Neem (Azadirachta Indica A. Juss.) Seed Powder and Extracts For the Control of the Spotted Stem Borer,Chilo Partellus (Swinhoe), on Maize and its Potential in Pest Management
    (Addis Ababa University, 1999-12) Tekie, Habte; C., R.(PhD)
    The efficacy of neem (A. indica A. Juss.) seed products for the control of the spotted stem borer, Chilo partelilis (Swinhoe) on H51l, ICZ3, ACV3, and Katumani maize cultivars was investigated in two geographical locations. Maize plants were either artificially infested with blackhead stage egg batches of C. partel/lIs, .01' were initially left unprotected for natnral infestation to take place before application of treatments. Neem seed powder (NSP) (3 g/plant), neem seed powder-sawdust mixtnre (NSP*SD) (6 g/plant), or 10 % aqueous neem seed extract (NSE) (500l/ha) were applied at four weeks after crop emergence (W AE) with untreated controls. Dipterex (D PTX) (l g/plant), or Sevin (500l/ha) were also used for comparison. Maize plants treated with neem seed products or chemical insecticides sustained much less borer holes, reduced leaf damage and stem tunneling than those in the controls in all the test cultivars (P < 0.001). NSP provided comparable and effective protection ill par with Dipterex or Sevin. NSP*SD and 10% NSE also showed more or less similar and appreciable effects in reducing leaf damage and stem tunneling by C. partelilis larvae. Foliar applications of neem seed products and chemical insecticides effectively suppressed the densities of C. partelills and subsequently improved the yield in all the test cultivars (P < 0.05). Foliar applications of neem seed products level to chemical insecticides in markedly reducing primary crop damages, in effectively suppressing the level of infestation by C. partelllls, and in improving yield in all the test cultivars. The findings unequivocally demonstrated that applications of neem seed products effectively control C. partelllls and avert serious crop damages and yield loss in field sitnations. In the laboratory, neonate C. panelills larvae were reared on artificial diet containing minute quantities of NSP (25, 50 or 100 ppm), 10% NSE (25, 50, or 100 ppm), or neem bitter concentrate (NBC) (5, 10, or 25 ppm). Artificial diet without neem seed products served as controls. Larvae were introduced singly into the cultnre vials containing 10 ml of artificial diet incorporating the treatment types and were either maintained on the same diet or transferred to standard diet two weeks after inoculation. Per cent larval survival, pupal weight, per cent pupation and emergence as an adult were examined and recorded. The duration of the developmental stages and total development periods were studied. Larval growth index (LGI) and Adult growth index (AGI) values were also determined. NSP (100 ppm) significantly reduced survival of larvae to the pupal stage and to adult emergence as compared to the other treatment types (P<0.005). NSP (50 ppm) and NBC (5, 10, 25 ppm) appreciably reduced the percentages of larvae that survived to pupation and adult emergence. NSP (50 and 100 ppm) markedly extended the larval period of C. partelills as compared to the other treatment types and the controls (P