Browsing by Author "Olotu, Moses I."

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    Effect of fungicides used for powdery mildew disease management on the African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae), a biocontrol agent of sap-sucking pests in cashew crops in Tanzania
    (2013-10) Olotu, Moses I.; Maniania, Nguya K.; Ekesi, Sunday; Seguni, Zuberi S.; Plessis, Hannalene D.
    The efficacy of pollination biology of Mesogyne insignis ispoorly known in fragmented forests of Amani NatureReserve. This study was conducted to determine the effectof forest fragmentation on potential pollinators of thisendangered species. Three intact forests and three forestfragments were selected for this study, the intact forestsserving as control. Visual observation of insects visitinginflorescences, insect trapping and pollinator exclusionexperiments were the methods employed in assessing pol-lination. Most members of the solitary bee genus Megachilewere found to be potential pollinators of M. insignis.Diversity of pollinators was significantly higher in intactforests than in forest fragments. Overall, the total numberof fruits set was significantly higher in intact forests thanin forest fragments, perhaps a reflection of the higherdiversity and abundance of potential pollinators in an in-tact forest. The pollination system of M. insignis is gen-eralist in terms of systematic group of pollinators, andforest fragmentation may have significant impact on thispollination pattern. A similar study should be conducted inother Eastern Arc Mountains where M. insignis grows tofind out whether the potential pollinators are similar or not
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    Effects of forest fragmentation on pollination of Mesogyne insignis (Moraceae) in Amani Nature Reserve forests, Tanzania
    (2011-10) 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) in the control of Helopeltis spp. (Hemiptera: Miridae) and Pseudotheraptus wayi (Hemiptera: Coreidae) in cashew crop in Tanzania
    (2012-12) Olotu, Moses I.; Plessis, Hannalene D.; Seguni, Zuberi S.; Maniania, Nguya K.
    Cashew, Anacardium occidentale, is an economically important cash crop for more than 300 000 rural householdsin Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii,H. schoutedeni and Pseudotheraptus wayi. The African weaver ant, Oecophylla longinoda, is an effective biocontrol agent ofhemipteran pests in coconuts in Tanzania, but its efficacy in the control of Helopeltis spp. and P. wayi in Tanzanian cashew hasnot been investigated so far. The aim of this study was therefore to evaluate the efficacy of O. longinoda in the management ofthese insect pests in the cashew crop at different sites of the Coast region of Tanzania
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    Potential of Oecophylla longinoda (Hymenoptera: Formicidae) for management of Helopeltis spp. (Hemiptera: Miridae) and Pseudotheraptus wayi (Hemiptera: Coreidae) in cashew in Tanzania
    (2013-09) Olotu, Moses I.
    Cashew, Anacardium occidentale Linnaeus, is an economically important cash crop for more than 300,000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii Miller, H. Schoutedeni Reuter and Pseudotheraptus wayi Brown. The African weaver ant (AWA), Oecophylla longinoda Latreille, is an effective biocontrol agent of hemipteran pests in coconuts in Tanzania; but its efficacy for the control of sap-sucking insects, especially Helopeltis spp. and P. wayi, has not been investigated so far in cashew crops in Tanzania. Field trials were carried out at the Coast region of Tanzania to evaluate the effect of seasonality and abundance of AWA on Helopeltis spp. and P. wayi. Results showed that AWA abundance expressed, as number of leaf nests per tree, and colonization of trails on main branches varied significantly between cashew-seasons and off-seasons. There was a negative correlation between numbers of nests and pest damage. AWA-colonized cashew trees had the lowest shoot damaged by Helopeltis spp., 4.8 and 7.5% in 2010 and 2011, respectively, compared to 36 and 30% in 2010 and 2011, respectively, in uncolonized cashew trees. Similarly, nut damage by P.wayi was lowest in AWA-colonized trees with 2.4 and 6.2% in 2010 and 2011, respectively, as compared to 26 and 21% in 2010 and 2011, respectively, in uncolonized trees. Interaction between AWA and dominant ant species, namely bigheaded ant (BHA), Pheidole megacephala Fabricius, and common pugnacious ant (CPA), Anoplolepis custodiens Smith, was examined because of the implication that the dominant ant species may have on the efficacy of AWA in its control of sap-sucking pests of cashew. Abundance of AWA was significantly negatively correlated to BHA (r(39) = -0.30; P < 0.0001) and CPA (r(39) = -0.18; P = 0.01) at Bagamoyo in 2010. A similar trend was also observed at Mkuranga. The presence of these ant species may therefore hinder effectiveness of AWA to control sap-sucking pests in cashew in Tanzania. Therefore, suppression of these two inimical ant species should be emphasized for effective control of the sap-sucking pests in cashew fields. It