Browsing by Author "Olotu, Moses I"

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    Effects of forest fragmentation on pollination of Mesogyne insignis (Moraceae) in Amani Nature Reserve forests, Tanzania
    (Blackwell Publishing Ltd, 2011-10-17) Olotu, Moses I; Ndangalasi, Henry J; Nyundo, Bruno A
    The efficacy of pollination biology of Mesogyne insignis is poorly known in fragmented forests of Amani Nature Reserve. This study was conducted to determine the effect of forest fragmentation on potential pollinators of this endangered species. Three intact forests and three forest fragments were selected for this study, the intact forests serving as control. Visual observation of insects visiting inflorescences, insect trapping and pollinator exclusion experiments were the methods employed in assessing pollination. Most members of the solitary bee genus Megachile were found to be potential pollinators of M. insignis. Diversity of pollinators was significantly higher in intact forests than in forest fragments. Overall, the total number of fruits set was significantly higher in intact forests than in forest fragments, perhaps a reflection of the higher diversity and abundance of potential pollinators in an intact forest. The pollination system of M. insignis is generalist in terms of systematic group of pollinators, and forest fragmentation may have significant impact on this pollination pattern. A similar study should be conducted in other Eastern Arc Mountains where M. insignis grows to find out whether the potential pollinators are similar or not.
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    Efficacy of the African weaver ant Oecophylla longinoda (Hymenoptera: Formicidae) control of Helopeltis spp. (Hemiptera: Miridae) and Pseudotheraptus wayi (Hemiptera: Coreidae) in cashew crop in Tanzania
    (Society of Chemical Industry, 2012-10-12) Olotu, Moses I; du Plessis, Hannalene; Seguni, Zuberi S; Maniania, Nguya K
    BACKGROUND:Cashew, Anacardiumoccidentale, is aneconomically important cash crop for morethan 300 000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardiiH. schoutedeni and Pseudotheraptus wayi. The African weaver ant, Oecophylla longinoda, is an effective biocontrol agent hemipteran pests in coconuts in Tanzania, but its efficacy in the control of Helopeltis spp. and P. wayi in Tanzanian cashew has not been investigated so far. The aim of this study was therefore to evaluate the efficacy of O. longinoda in the management these insect pests in the cashew crop at different sites of the Coast region of Tanzania. RESULTS: Colonisation levels of O. longinoda, expressed as weaver ant trails, varied from 57.1 to 60.6% and from58.3 to 67.5% 2010 and 2011 respectively. The mean number of leaf nests per tree varied from five to eight nests in 2010 and from five to nine nests in 2011. There was a negative correlation between numbers of nests and pest damage. Oecophylla longinoda-colonised cashew trees had the lowest shoot damage by Helopeltis spp. of 4.8 and 7.5% in 2010 and 2011, respectively, as opposed uncolonised cashew trees with 36 and 30% in 2010 and 2011 respectively. Similarly, nut damage by P. wayi was lowest in longinoda-colonised trees, with only 2.4 and 6.2% in 2010 and 2011 as opposed to uncolonised trees with 26 and 21%. CONCLUSION: Oecophylla longinoda is an effective biocontrol agent of the sap-sucking pests of cashew in the Coast region Tanzania and should be considered as an important component of IPM.