Transmission of Cassava brown streak virus by Bemisia tabaci (Gennadius)

Abstract

Two whitefly species, Bemisia afer (Priesner & Hosny) and B. tabaci (Gennadius) were used in transmission experiments with Cassava brown streak virus (CBSV) (Ipomovirus; Potyviridae). Adults of whiteflies were given access to CBSV by containing them in clip cages on CBSV-infected cassava plants. Whiteflies were then transferred, together or separately, to CBSD-susceptible cassava plants of var. ÔAlbertÕ in a controlled environment. In glasshouse experiments, whiteflies were caged with CBSV-infected and virusfree cassava plants. Transmission of CBSV was sporadic and occurred in three of seven experiments when inoculated by B. afer and B. tabaci or B. tabaci alone, but not by B. afer alone. However, rate of transmission was low (maximum 22%) even when using high whitefly numbers of up to 120 per target plant. Successful transmission was confirmed by the detection of CBSV by reverse transcription-polymerase chain reaction. Spread of cassava brown streak disease (CBSD) in the field in Tanzania coincided with increases in whitefly numbers; further supporting the evidence that B. tabaci is a vector of CBSV. The results of this study establish for the first time that B. tabaci is the vector of CBSV, similar to other ipomoviruses.www.blackwell-synergy.com

Approaches to diagnosis and detection of cassava brown streak virus (<i>potiviridae: ipomovirus</i>) in field-grown cassava crop.

“…The absence of CBSV in seeds obtained from diseased plants was consistent with findings of Maruthi et al [18]. The detection of CBSV in flowers and fruits of CBSVinfected plants but not in seeds suggests the possible existence of mechanisms that excludes the virus from the embryo as reported by Carroll [26] in Barley stripe mosaic virus (BSMV).…”

“…Consequently, the requirement for additional molecular detection techniques for CBSV becomes important. Molecular techniques for CBSV-detection have been reported [4,5,18]. However, the efficiencies of these techniques have never been tested on bulked samples for fast screening of large volume of samples.…”

Characterization of Brown Streak Virus–Resistant Cassava

“…Our virus inoculation method resulted in 100% infection rates in the susceptible 60444 scions in all experiments. Infection rates obtained by the top grafting method are more consistent and reproducible compared to other inoculation methods reported to date (Maruthi et al, 2005;Mohammed et al, 2012;Ogwok et al, 2012).…”

Cassava brown streak disease: a threat to food security in Africa

“…(Homoptera: Aleyrodidae), was proposed to be the vector of CBSVs as early as the 1930s (Storey & Nichols, 1938), but this was not confirmed until many years later (Maruthi et al, 2005). Unlike CMGs, which are transmitted by B. tabaci in a persistent manner, CBSVs are transmitted semi-persistently, like other ipomoviruses, and are not retained for more than 24 h (Dombrovsky et al, 2014;Jeremiah, 2014;M.…”

“…Recently, Vanderschuren et al (2012) generated transgenic cassava lines by transforming the CMD-resistant Nigerian landrace TME7 (Oko-Iyawo) with the CBSV CP RNAi construct. The main hurdles in screening transgenic cassava lines for CBSD resistance have been the lack of infectious clones of UCBSV or CBSV, and poor whitefly transmission under greenhouse conditions (Maruthi et al, 2005). Consequently, labourintensive grafting is the only option for screening CBSD resistance prior to field trials.…”