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BACKGROUND: Cashew, Anacardium occidentale, is an economically important cash crop for more than 300000 rural households in 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 of 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 of 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 from 58.3 to 67.5% in 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 to uncolonised cashew trees with 36 and 30% in 2010 and 2011 respectively. Similarly, nut damage by P. wayi was lowest in O. 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 of Tanzania and should be considered as an important component of IPM. © 2012 Society of Chemical Industry. Source

Lyimo L.D.,The University of Dodoma | Tairo F.M.,Mikocheni Agricultural Research Institute MARI | Rweyemamu C.L.,Sokoine University of Agriculture
International Journal of Integrative Biology

Genetic diversity of thirty nine (39) Tanzanian landraces of cassava (Manihot esculenta Crants) was studied using below and above-ground morphological descriptors followed by genomic DNA characterization using 13 SSR primers. Analysis of variance showed that all the characters evaluated were significantly different (P<0.01) between the genotypes. The dendrogram obtained using both phenotypic and molecular markers separated the genotypes into three major clusters with a Euclidean distance ranging from 0.53 to 0.91 and 0.33 to 0.88 respectively. The 85 SSR loci revealed a total of 89 alleles, out of which 75 alleles were found to be polymorphic with 84% level of polymorphism. The results, summarized on both dendrograms, showed wide genetic diversity among landraces providing scope for their improvement through hybridization and selection. In both methods no cassava duplicate was identified, though the most morphologically closely related cassava landraces were Sindani and Ndingiwaka with similarity coefficient of 0.91. Similarly the most genetically closely related cassava landraces were Mama and Mahuhu that had Jacquard's coefficient of 0.88. High polymorphic information content (PIC) was recorded in all primers except SSRY171 which had 0.22. The plot of the first three principal components scored generated 3-dimension scatter graph that showed the relationship between the 39 cassava landraces. © OmicsVista Group, All rights reserved. Source

Du Plessis H.,North West University South Africa | Seguni Z.S.,Mikocheni Agricultural Research Institute MARI
International Journal of Tropical Insect Science

The efficacy of fish- and hydramethylnon-based baits for conservation of the African weaver ant (AWA) Oecophylla longinoda Latreille was evaluated at orchards in Bagamoyo and Mkuranga districts, Coast region of Tanzania, during the cashew off-seasons in 2011 and 2012. The baits were applied at monthly intervals; the dynamics of AWA were monitored by counting the number of leaf nests/tree and the colonization trails on main branches. The numbers of leaf nests recorded before baiting ranged between 3.5 and 5.3 and were not significantly different at both sites and in both seasons; after baiting, they ranged between 3.2 and 11.6 at Bagamoyo and between 3.0 and 10.2 at Mkuranga. The colonization of AWA trails recorded before baiting was also not significantly different at both sites and in both seasons and ranged between 37.9 and 50.0%; after baiting, this ranged between 35.9 and 75.1% at Bagamoyo and between 34.6 and 79.2% at Mkuranga. The provision of fish- and hydramethylnon-based baits can effectively contribute to the conservation of AWA during the cashew off-seasons. The fish-based bait is cheaper and more easily affordable by local farmers and can, therefore, be used as an alternative diet for AWA at this time. Copyright © ICIPE 2015. Source

Bull S.E.,University of Bath | Ndunguru J.,Mikocheni Agricultural Research Institute MARI | Gruissem W.,ETH Zurich | Beeching J.R.,University of Bath | Vanderschuren H.,ETH Zurich
Plant Cell Reports

Knowledge and technology transfer to African institutes is an important objective to help achieve the United Nations Millennium Development Goals. Plant biotechnology in particular enables innovative advances in agriculture and industry, offering new prospects to promote the integration and dissemination of improved crops and their derivatives from developing countries into local markets and the global economy. There is also the need to broaden our knowledge and understanding of cassava as a staple food crop. Cassava (Manihot esculenta Crantz) is a vital source of calories for approximately 500 million people living in developing countries. Unfortunately, it is subject to numerous biotic and abiotic stresses that impact on production, consumption, marketability and also local and country economics. To date, improvements to cassava have been led via conventional plant breeding programmes, but with advances in molecular-assisted breeding and plant biotechnology new tools are being developed to hasten the generation of improved farmer-preferred cultivars. In this review, we report on the current constraints to cassava production and knowledge acquisition in Africa, including a case study discussing the opportunities and challenges of a technology transfer programme established between the Mikocheni Agricultural Research Institute in Tanzania and Europe-based researchers. The establishment of cassava biotechnology platform(s) should promote research capabilities in African institutions and allow scientists autonomy to adapt cassava to suit local agro-ecosystems, ultimately serving to develop a sustainable biotechnology infrastructure in African countries. © 2011 Springer-Verlag. Source

Bredeson J.V.,University of California at Berkeley | Lyons J.B.,University of California at Berkeley | Prochnik S.E.,U.S. Department of Energy | Wu G.A.,U.S. Department of Energy | And 22 more authors.
Nature Biotechnology

Cassava (Manihot esculenta) provides calories and nutrition for more than half a billion people. It was domesticated by native Amazonian peoples through cultivation of the wild progenitor M. esculenta ssp. flabellifolia and is now grown in tropical regions worldwide. Here we provide a high-quality genome assembly for cassava with improved contiguity, linkage, and completeness; almost 97% of genes are anchored to chromosomes. We find that paleotetraploidy in cassava is shared with the related rubber tree Hevea, providing a resource for comparative studies. We also sequence a global collection of 58 Manihot accessions, including cultivated and wild cassava accessions and related species such as Ceará or India rubber (M. glaziovii), and genotype 268 African cassava varieties. We find widespread interspecific admixture, and detect the genetic signature of past cassava breeding programs. As a clonally propagated crop, cassava is especially vulnerable to pathogens and abiotic stresses. This genomic resource will inform future genome-enabled breeding efforts to improve this staple crop. © 2016 Nature America, Inc. All rights reserved. Source

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