Vectors of Plant Viruses of Crop Plants in Southeast Asia 169
manner by M. persicae and is also reported as
seed-transmitted (Pudashini et al. 2013 ).
Whitefly Whitefly, Bemisia tabaci (Hemiptera:
Aleyrodidae) transmitted viruses (WTVs) occur
predominantly in the tropics where their vec-
tors are most abundant. Several crops in Kar-
nataka, India are infected with WTVs causing
enormous losses (Muniyappa 1980 ; Muniyappa
and Veeresh 1984. Saikia and Muniyappa 1989 ;
Banks et al. 2001.
B. tabaci originated in the tropics and sub-
tropics, has rapidly spread as a consequence of
the international trade in flowers and other nurs-
ery stock. Because of its wide host range, rapid
propagation, and superior ability to transmit
virus, B. tabaci has become one of the most im-
portant pests in field crops worldwide. B. tabaci
is a complex of numerous genetically distinct
populations, previously referred to as biotypes
and now recognized as cryptic species. There
are about 24 cryptic species of B. tabaci, includ-
ing the two most widely distributed and invasive
biotypes, B and Q, hereafter referred to as B and
Q whiteflies. B. tabaci is the only known vector
of TYLCV, which seriously reduces tomato pro-
duction and quality. TYLCV is a single-stranded
DNA (ssDNA) plant virus in the genus begomo-
virus, family Geminiviridae that originated in the
Middle East (Cohen and Harpaz 1964 ; Varma and
Malathi 2003 ) Begomoviruses are transmitted by
B. tabaci in a circulative manner and persist in
the whitefly vector. Transmission of tomato leaf
curl virus was successful when B. tabaci (Genn)
were allowed to feed on leaf curl infected tomato
for 24 h AAP and IAP with 10–15 whiteflies.
As early as 1947, mosaic on common weed,
Malvastrum coromandelianum, was reported,
and now it is whitefly transmitted begomovi-
rus (Harrison et al. 1991 ). Bhendi yellow vein
mosaic (Harrison et al. 1991 ), Cassava mosaic
(Mathew and Muniyappa 1991 ), Cotton leaf curl
(Nateshan et al. 1996 ), croton yellow vein mo-
saic (Mandal and Muniyappa 1991 ), Hibiscus
leaf curl (Rajeshwari et al. 2005 ), Pumpkin yel-
low vein mosaic (Muniyappa et al. 2003 ), Jat-
ropha mosaic (Aswatha Narayana et al. 2007 ),
Tobacco leaf curl (Valand and Muniyappa 1992 ),
and Tomato leaf curl (Muniyappa et al. 2000 )
begomoviruses were transmitted by B. tabaci in
a semipersistent manner (circulative manner).
For the first time, Cowpea mild mottle virus
(CMMV) has been demonstrated transmitted by
B. tabaci in a nonpersistent manner. B. tabaci
adults acquired CMMV in 10 min transmitted it
within 5 min to soybeans. Starvation before ac-
quisition had no effect upon transmission, but
starvation after acquisition decreased transmis-
sion frequency (Muniyappa and Reddy 1983 ).
The Bhendi yellow mosaic virus (BYVMV) dis-
ease is caused by the whitefly ( B. tabaci) trans-
mitted virus complex consisting of a monopartite
begomovirus BYVMV and a betasatellite mol-
ecule. The causal virus and its associated betasat-
ellite molecule infect the crop at all the stages
(Jose et al. 2003 ).
The infection of BYVMV to Bhendi under
natural field conditions was depending on the en-
vironmental parameters, crop characteristics, and
efficient vector whitefly ( B. tabaci) population
(Khan and Mukhopadhyay 1985 ; Bhagabati and
Goswami 1972 ). Susceptibility of cultivars en-
courages its incidence in the field in the presence
of the active vectors. Considering it as one of the
major constraints of okra cultivation, it is essential
to gather basic information to understand the na-
ture of infection, source and gradual increase with
the increase of plant age survival capacity of the
virus and mode of spread among different varieties
in a cropping season (Karri and Acharyya 2012 ).
High incidence of TYLCV in most tomato-
growing pockets and yield losses of 40 % or even
higher in Risingpatan, Tanahun and Kudule, of
western hills of Nepal is recorded. The TYLCV
vector, whitefly ( B. tabaci), was found active
throughout the crop-growing period in commer-
cial tomato-growing pockets ( Sita et al. 2001 ).
In China, TYLCV and tomato yellow leaf curl
China virus (TYLCCNV) were shown to be hori-
zontally transmitted by both B and Q biotypes
of whitefly, but transmission frequency was low
(Wang et al. 2010 ). In 2006, TYLCV was intro-
duced into China, approximately 10 years after
the introduction of an invasive whitefly, B. taba-
ci B biotype. After the introduction of Q biotype
into China in 2003, the prevalence and spread of