Browsing by Author "Boni, Simon Boniface"

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    Assessment of biological characteristics of the whitefly, bemisia tabaci (gennadius) (hemiptera: sternorrhyncha: aleyrodidae) populations transmitting cassava mosaic geminiviruses in Tanzania
    (University of Dar es Salaam, 2014) Boni, Simon Boniface
    Cassava, Manihot esculenta (Crantz) is an important staple crop in much of sub-Saharan Africa. Information on the causes of extraordinary fecundity of Bemisia tabaci (Genn.) which is a vector for cassava mosaic geminiviruses (CMGs) that cause cassava mosaic disease (CMD) and its super-abundance in the CMD pandemic areas has been limited. In the present study, genetic sequencing of mtCOI, development duration and mortality of immature stages and response of B. tabaci to cassava varietal influences have been studied on cassava varieties at different CMG infection status in the Lake and Coastal Zones of Tanzania. Four B. tabaci genotypes: TZ CA1, TZ CA2, TZ CA3 and TZ Non-CA were revealed. B. tabaci laid more eggs on CMG-infected cassava plants but with increased survival on CMG-free plants. The development duration of the immature stages of B. tabaci did not significantly differ with CMG infection in both zones but overall, it tended to be shorter in the Coastal Zone than in the Lake Zone. B. tabaci did not show significant preferences for improved CMD-resistant varieties over CMD-susceptible varieties. This study has demonstrated an association of a distinct B. tabaci genotype/biotype, TZ CA1 = UG1, with CMD pandemic and the super-abundance of the vector. The CMD pandemic-based and the CMD non pandemic-based B. tabaci differ in their fitness to the environment, with the former, better favoured than the later. More studies relating this subject are recommended. The knowledge gained from this study can be used in the formulation of effective control and management components of B. tabaci to minimize the spread of the cassava viruses. Ultimately, the findings can contribute to increased productivity of cassava, leading to improved food security and poverty reduction in the country.