Abstract
After 2007, upsurges of whiteflies on cassava plants and high incidences of cassava diseases were observed in Central African Republic. This recent upsurge in the abundance of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) was directly linked to serious damage to cassava crops resulting from spread of whitefly-borne cassava mosaic geminiviruses (CMGs). There is currently very little information describing whitefly populations on cassava and associated crops in Central African Republic. The current study aimed to address this gap, and to determine whether the increasing damage associated with B. tabaci whiteflies was the consequence of a new invasion, or an upsurge of a local population. The molecular genetic identification and phylogenetic relationships of 898 B. tabaci adult individuals collected from representative locations (54) throughout CAR were determined based on their mitochondrial cytochrome oxidase I sequences (mtCOI). Field and ecological data were also collected from each site, including whitefly abundance, CMD incidence, host plants colonized by B. tabaci and agro-ecological zone. Phylogenetic analysis of the whitefly mtCOI sequences indicated that SSA1 (-SG1, -SG2), SSA3, MED, MEAM1 and Indian Ocean (IO) putative species occur in CAR. One specific haplotype of SSA1-SG1 (SSA1-SG1-P18F5) predominated on most cassava plants and at the majority of sites. This haplotype was identical to the SSA1-SG1 Mukono8-4 (KM377961) haplotype that was recorded from Uganda but that also occurs widely in CMD pandemic-affected areas of East Africa. These results suggest that the SSA1-SG1-P18F5 haplotype occurring in CAR represents a recent invasive population, and that it is the likely cause of the increased spread and severity of CMD in CAR. Furthermore, the high mtDNA sequence diversity observed for SSA1 and its broad presence on all sites and host plants sampled suggest that this genetic group was the dominant resident species even before the arrival of this new invasive haplotype.
Highlights
Cassava (Manihot esculenta Crantz, Euphorbiaceae) is a major staple crop in sub-Saharan Africa due to its high calorie content, low production cost and ability to adapt to different soil types and climatic conditions, most in central Africa [1]
cassava brown streak disease (CBSD) is known to be caused by two plant RNA viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), occurring alone or in co-infection
The current study examined 898 B. tabaci individuals collected from cassava fields and associated crops in 54 sites spread throughout Central African Republic (CAR) (Table 1, Fig 5)
Summary
Cassava (Manihot esculenta Crantz, Euphorbiaceae) is a major staple crop in sub-Saharan Africa due to its high calorie content, low production cost and ability to adapt to different soil types and climatic conditions, most in central Africa [1]. Yield losses attributed to CMD were minor to moderate for many years, following the first outbreaks occurring during the 1920s-30s It became much more damaging following the development of an unusually severe form of the disease in Uganda that spread to neighboring parts of East and Central Africa and became a regional pandemic [9]. CBSD is known to be caused by two plant RNA viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (family Potyviridae; genus Ipomovirus), occurring alone or in co-infection. This disease has recently affected much of the Great Lakes Region of East and Central Africa [10,11,12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
