170 N. Nagaraju et al.
TYLCV started to accelerate and found that the two
biotypes might not be equally competent vectors
of TYLCV. B. tabaci B and Q biotypes needed 48
and 12 h AAP, respectively, to reach their respec-
tive maximum viral loads (Pan et al. 2012 ). Vector
salivation is essential for TYLCV transmission.
The transmission efficiency of TYLCV by the
whitefly vector, B. tabaci is high when it asso-
ciated with the bacterial symbiont Hamiltonella
with a high frequency with close association of
bacterial symbiont Hamiltonella with high fre-
quency. The Hamiltonella helps in retention and
transmission efficiency of TYLCV helps in re-
tention and transmission efficiency of TYLCV
by the whitefly vector (Pan et al. 2013 ). Tomato
leaf curl virus (ToLCV-Ban4) was transmitted by
single whitefly, but five insects were necessary to
achieve 100 % transmission. Minimum AAP and
IAP were 10 min and 20 min, respectively. A la-
tent period of 6 h was required for B. tabaci to
efficiently infect tomato test plants. Following a
24 h AAP, the insect retained its ability to infect
tomato test plants for 12 days, but not for its entire
life. In one insect/one plant inoculation tests, fe-
male whiteflies were more efficient (~95 %) than
males (~25 %) in transmitting the virus (Muniyap-
pa et al. 2000 ). Similar virus vector relationships
were found in whitefly transmitted viruses such
as Croton yellow vein mosaic virus (CYVMV)
(Mandal and Muniyappa 1991 ); ICMV (Mathew
and Muniyappa 1991 ) and pumpkin yellow vein
mosaic virus (PYVMV) (Muniyappa et al. 2003 ).
The existence of a short incubation period and
persistence of virus for 12 days in the vector sug-
gests that the virus is circulative but not propaga-
tive. The long persistence of ToLCV in vector and
ability of single whitefly to cause disease, togeth-
er with intensive cultivation of tomato throughout
the year and abundance of weed hosts are impor-
tant factors for very high incidence of ToLCV in
nature (Muniyappa et al. 2000 ). At least 25 B.
tabaci adults were required for the transmission
of hibiscus leaf curl virus (HLCV) from hibiscus
to hibiscus with minimum AAP and IAP of 12 and
24 h, respectively (Rajeshwari et al. 2005 ). The
minimum AAP and IAP were 30 min (10 % trans-
mission) and 15 min (10 % transmission), respec-
tively, and female B.tabaci are able to transmit
TYLCV. The efficiency of transmission increased
by increasing both AAP and IAP, as well as insect
numbers (Ajlan et al. 2007 ).
The B-biotype B. tabaci was first observed in
Kolar, Karnataka in India, during 1999 on toma-
to. High population of B-biotype was responsible
for outbreak of tomato leaf curl virus which re-
sulted in total failure of tomato crop (Banks et al.
2001 ). The B-biotype was more common than
the indigenous B. tabaci, in locations where it
had been present more than 2 years. It was found
in most districtrs of Karnataka, Andhra Pradesh
and Tamil Nadu, South India. (Rekha et al. 2005 ;
Shankarappa et al. 2007 ).
Virus causing yellow vein disease on Calen-
dula officinalis L.was transmitted from natu-
rally infected C.Officinalis to healthy seedlings
of C. officinalis through whiteflies. inoculation.
A single whitefly could transmit the virus and
showed 20.55 % infection and 15 whiteflies were
required for 100 % transmission. The minimum
acquisition access feeding period and minimum
inoculation access feeding period for the present
virus were 10 min and 30 min, respectively. Ac-
quisition access feeding period and inoculation
access feeding period was 100 % at 6 h and 3 h,
respectively. A pre-acquisition access feeding pe-
riod of 3 h or more gave 100 % transmission. Post
acquisition access feeding period of whiteflies
did not have any effect in increasing transmis-
sion of CYVV. As post acquisition access feeding
period increased, the transmission of CYVV was
gradually decreased (Bushra Afreen 2000 )
[PYVMV was transmitted to healthy pumpkin
plants only by B. tabaci and not through sap inoc-
ulation. A single viruliferous whitefly was able to
cause 21.67 % infection but 100 % infection was
obtained when 15 whiteflies were used per plant.
The acquisition threshhold and the inoculation
threshhold periods for the whitefly were 6 h and
3 h, respectively. The percentage of transmission
increased with increase in both acquisition and in-
oculation feeding periods. A preacquisition star-
vation period of 3 h gave 100 % transmission, but
postacquisition starvation was found to reduce the
transmission efficiency (Jayashree et al. 1999 ).
Dolichos yellow mosaic virus (DoYMV)
was transmitted poorly by B. tabaci. Whitefly