Research Publications

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Start date: 2002End date: 2009

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Now showing 1 - 10 of 48
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    Putting on a Brave Face: The Experiences of Women living with HIV and AIDS in Informal Settlements of Nairobi Kenya
    (Taylor & Francis, 2007-03-07) Amuyunzu-Nyamongo, M.; Okeng'o, L.; Wagura, A.; Mwenzwa, E.
    This paper examines two key dimensions of HIV and AIDS in sub-Saharan Africa, namely poverty and gender, within the particular context of informal settlements. The study, conducted in five informal settlements of Nairobi, Kenya explored the challenges facing women living with HIV and AIDS (WLWA) in informal settlements in Nairobi in terms of the specific risk environments of informal settlements, the support they receive and their perceptions of their future. The data were gathered through an interviewer-based questionnaire administered to 390 WLWA and 20 key informant interviews with Kenya Network of Women with AIDS (KENWA) project personnel. The results show that for WLWA in informal settlements, poverty and poor living conditions combine to increase the risk environment for HIV infection and other opportunistic infections and that the WLWA then face HIV- and AIDS-related problems that are exacerbated by poverty and by the poor living environments. In response, the WLWA had devised coping strategies that were largely centred on survival, including commercial sex work and the sale of illicit liquor, thus increasing their susceptibility to re-infections. Insecurity in informal settlements curtailed their participation in income generating activities (IGAs) and increased their risk of rape and HIV re-infection. Recognising the disadvantaged position of communities in informal settlements, the non-governmental organizations (NGOs), community-based organizations (CBOs) and faith-based organizations (FBOs) provide a range of services including HIV and AIDS information and therapy. Paradoxically, living in urban informal settlements was found to increase WLWA's access to HIV and AIDS prevention and treatment services through NGOs and social networks that are not found in more established residential areas. The sustainability of these services is, however, questioned, given the lack of local resources, weak state support and high donor dependency. We suggest that the economic and tenure insecurity found among WLWA demands in response consistent support through comprehensive, sustainable HIV and AIDS services complemented by social networks and community sensitisation against stigma and discrimination. Fundamentally, the upgrading of informal settlements would address the wider risk environments that exacerbate the poor health of the WLWA who line in them.
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    Evaluation of Ephestia kuehniella and Corcyra cephalonica as hosts for mass rearing trichogramma species nr. Mwanzai and trichogrammatoidea species nr. Lutea
    (2008-01-16) Migiro, L. N.; Gitonga, L. M.; Sithanantham, S.
    Production of vegetables free of chemical pesticides requires, among other things, use of biocontrol agents that can be effectively and efficiently produced in large quantities. Two factitious hosts were evaluated for their suitability in mass rearing of two native Trichogrammatids. Egg cards bearing host eggs were separately offered to female parasitoids in glass vials and allowed to parasitise for 24 hours. New egg cards were offered daily till death of the female parasitoid. The number of eggs parasitised, emerged adult progeny and female progeny differed significantly between the two parasitoids, with Trichogramma sp. nr. Mwanzai appearing to be superior to Trichogrammatoidea sp. nr. lutea.There were no differences in the mass production efficiency and quality of progeny between the Ephestia kuehniella and Corcyra cephalonica. The two hosts can be effectively used for mass production of either of the parasitoids.
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    The Critical Onion Growth Stages For Selective Protection From Thrips Tabaci Lindeman (Thysanoptera:Thripidae) Infestation
    (Kenya Agricultural Research Institute, Nairobi (Kenya), 2006-01) Waiganjo, M. M.; Sithanantham, S.; Mueke, J. M.; Gitonga, L. M.
    Field trials were conducted during 2000-2001 at KARIandrsquo;s Mwea-Tebere and Kiboko farms to establish the effect of onion thrips, Thrips tabaci Lindeman on onion bulb yields and to identify the critical onion growth stage for selective protection from the pest infestation. Yield reductions of 59 and 27% were recorded in the first and second crops respectively at Mwea-Tebere, but no significant yield reductions were observed in a third crop grown at Kiboko with low thrips infestation. A significant onion yield response to thrips infestation was observed during the 2nd month after transplanting (bulb-formation) and 3rd month after transplanting (bulb-enlargement), but no significant response was observed during the 1st month (pre-bulbing) and 4th month (maturation stage). Onion protection during bulb-formation and enlargement stages only, resulted in higher marginal returns than full season pesticide application. The studies suggest that control recommendations for onion could be refined to optimize need-based protection.
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    Preventive control alternatives to routine foliar spray against Thrips tabaci in onions
    (2008-10) Waiganjo, M.; Sithanantham, S.; Gitonga, Linus; Mueke, J. M.
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    Effect of temperature on the development of Orius albidipennis Reuter, a predator of the African legume flower thrips, Megalurothrips sjostedti Trybom
    (2002) Gitonga, L. M.; Löhr, B.; Overholt, W. A.; Magambo, J. K.; Mueke, J. M.
    The effects of temperature on the development of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae), reared on its prey, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), were studied in the laboratory. Nymphal mortality was 87, 48 and 38 % at 20, 25 and 30 °C, respectively. With the exception of first-instar nymphs, percentage mortality was lowest at 25 °C. Pre-oviposition period and longevity decreased with an increase in temperature. Mean daily and total fecundity were 2.1 and 76.4 respectively at 25 °C. The mean developmental period from oviposition to adult eclosion was 27.7, 14.1 and 10.9 days at 20, 25 and 30 °C respectively. There was a linear relationship between temperature and developmental rate (1 /day) of O. albidipennis. Lower thermal thresholds were 13.8, 13.5, 12.7, 15.0, 13.8 and 12.5 °C for eggs and nymphal stages 1 to 5, respectively, with the corresponding average degree-day requirement of 46.9, 42.6, 33.3, 29.2, 26.1 and 51.4 days, respectively. The implications of these results for biological control of thrips are discussed.
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    Scope for genetic enhancement of the parasitisation potential of four native strains of Trichogrammatoidea sp. nr. lutea Girault (Hymenoptera: Trichogrammatidae
    (Taylor & Francis, 2007-09) Baya, Joseph M.; Sithanantham, S.; Gitonga, Linus; Osir, Ellie
    In response to emerging interest in commercial mass production of Trichogramma for Helicoverpa armigera biocontrol in eastern Africa, laboratory experiments were undertaken to assess the scope for genetic enhancement of the parasitisation potential of native strains of the local common trichogrammatid species, Trichogrammatoidea sp. nr. lutea. Four promising strains (ex-Kilifi – Kilifi District, ex-Kwa Chai – Kibwezi District, ex-Rarieda – Bondo District and ex-Ebuhayi, Kakamega District) were tested for cross-mating in reciprocal combinations with focus on fecundity and progeny female ratio. While all the crosses resulted in F1 progeny of both sexes, significant differences were observed between homogamic and reciprocal heterogamic crosses in fecundity, progeny production, proportion of female progeny and adult longevity. Among all the crosses, the cross between ex-Rarieda strain females and ex-Kilifi strain males resulted in progeny that was significantly superior in fecundity and progeny female ratio. Conversely, Kilifi strain females crossed to males from ex-Rarieda strain gave rise to progeny with relatively low fecundity and female ratio. There were significant differences between homogamic crosses and most reciprocal heterogamic crosses in the major biological attributes. Genotypic and phenotypic variance-covariance matrices generated for six life-history traits showed high positive correlations for most traits in both inbred (P<0.05) and reciprocal heterogamic crosses (P<0.05 and P<0.001). Fecundity and number of female offspring were the most important factors in the heterogamic crosses. The results confirmed the scope for genetic enhancement through inter-strain crossing for improving the field impact potential of T. sp. nr. lutea being targeted for commercial mass production.
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    HOST-PLANT ACCEPTANCE, FECUNDITY AND LONGEVITY OF Tetranychus evansi (Acari: Tetranychidae) ON SELECTED TOMATO ACCESSIONS
    (2009) Murungi, L. K.; Knapp, M.; Masinde, P. W; Onyambu, G.; Gitonga, L.; Agong, S. G.
    Seventomato (Lycopersicon sp.) accessions wereevaluated for their resistance to thetomato red spider mite, Tetranychus evansi Baker and Pritchard, in the laboratory. Data recorded was: (i) trichome density and (ii) fecundity and longevity. Whole potted intact tomato plants were used for the olfactometer bioassays, while leaf disk sections were used for the glass bridge bioassays. There was a significant (P<0.05) negative correlation between fecundity and longevity with the density of trichome types I and IV. Significantly more females chose the direction with ‘Money Maker’ (susceptible accession) when compared to other accessions. Thus, trichome density and plant-emitted volatiles seem to play an important role in host- plant selection of spider mites.