A study of the super-abundant Bemisia tabaci (Gennadius) species complex (Hemiptera: Aleyrodidae) in cassava mosaic disease pandemic areas in Tanzania
type: CreativeWork
description: Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex comprising morphologically indistinguishable but genetically variable populations. It is the vector of cassava mosaic geminiviruses (CMGs) causing cassava mosaic (CMD) disease to cassava (Manihot esculenta Crantz). After the outbreak and spread of a severe CMD from Uganda to several East and Central African countries, the production of cassava has been impaired. The severe CMD pandemic is mainly characterized by high disease severity and super-abundant populations of B. tabaci. This research sought to study the super-abundant populations in Tanzania. The main objectives were to assess the genetic diversity and distribution of cassava-associated B. tabaci, to assess the endosymbiont fauna, and to investigate the population structure of B. tabaci populations found in Tanzania. Hence, whiteflies collected through several field surveys were analysed using mitochondrial and nuclear markers. The four B. tabaci putative species found to be present in the study area based on mitochondrial data were sub-Saharan Africa 1 (SSA1), Mediterranean (MED), Indian Ocean (IO) and East Africa 1 (EA1). There were four sub-groups (SG) under SSA1 which included SSA1-SG1, SSA1-SG2, SSA1-SG1-2 and SSA1-SG3. SSA1-SG1 was found to be the pandemic-associated B. tabaci in Tanzania, being found predominantly in the pandemic affected north-western part of the country. The SSA1-SG2 was shown to be present in the pandemic-unaffected central part while SSA1-SG3 was exclusively found confined to the coastal parts. Microsatellite data also identified SSA1, MED and IO B. tabaci putative species as well as B. afer. It further revealed two sub-clusters within SSA1, which were each dominating different geographic areas across the sampling zones. One type predominated in the north-western pandemic affected part of Tanzania but diminishing in frequency towards the south-east, whilst the other became increasingly common until it…
abstract: Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex comprising morphologically indistinguishable but genetically variable populations. It is the vector of cassava mosaic geminiviruses (CMGs) causing cassava mosaic (CMD) disease to cassava (Manihot esculenta Crantz). After the outbreak and spread of a severe CMD from Uganda to several East and Central African countries, the production of cassava has been impaired. The severe CMD pandemic is mainly characterized by high disease severity and super-abundant populations of B. tabaci. This research sought to study the super-abundant populations in Tanzania. The main objectives were to assess the genetic diversity and distribution of cassava-associated B. tabaci, to assess the endosymbiont fauna, and to investigate the population structure of B. tabaci populations found in Tanzania. Hence, whiteflies collected through several field surveys were analysed using mitochondrial and nuclear markers. The four B. tabaci putative species found to be present in the study area based on mitochondrial data were sub-Saharan Africa 1 (SSA1), Mediterranean (MED), Indian Ocean (IO) and East Africa 1 (EA1). There were four sub-groups (SG) under SSA1 which included SSA1-SG1, SSA1-SG2, SSA1-SG1-2 and SSA1-SG3. SSA1-SG1 was found to be the pandemic-associated B. tabaci in Tanzania, being found predominantly in the pandemic affected north-western part of the country. The SSA1-SG2 was shown to be present in the pandemic-unaffected central part while SSA1-SG3 was exclusively found confined to the coastal parts. Microsatellite data also identified SSA1, MED and IO B. tabaci putative species as well as B. afer. It further revealed two sub-clusters within SSA1, which were each dominating different geographic areas across the sampling zones. One type predominated in the north-western pandemic affected part of Tanzania but diminishing in frequency towards the south-east, whilst the other became increasingly common until it…
author: TAJEBE, LENSA SEFERA
language: eng
keywords: cassava, East Africa, whitefly, pandemic front, secondary symbionts, gene flow, hybridization, microsatellite, population structure
date published: 2014-12-10
date modified: 2026-07-24T01:35:01Z
provider: Università degli Studi di Catania
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Università degli studi di Catania

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property ID: Handle
value: https://hdl.handle.net/20.500.11769/589150