Vectors of Plant Viruses of Crop Plants in Southeast Asia 171
acquired DoYMV in 6 h and transmitted in 1 h. A
minimum of four B. tabaci adults were required
for the transmission of virus with 1.6 % efficien-
cy which increased to 18.3 % using 50 adults/
plant after 24 h AAP and IAP (Manjunath and
Muniyappa 1995 ; Maruthi et al. 2006 ). The rate
of transmission of Jatropha mosaic virus (JMV)
by B. tabaci was low (4 %) when 5 or 10 adults
were used for inoculation. About 25 adults that
were given 24 h AAP and 48 h IAP transmitted
the virus to an extent of 40 % (Aswatha Narayana
et al. 2007 ).
A single whitefly was capable of transmitting
chilli leaf curl virus, and eight or more whiteflies/
plant resulted in 100 % transmission. The mini-
mum AAP and IAP were 180 and 60 min, respec-
tively. The virus persisted in whiteflies for up to
5 days post acquisition (Senanayake et al. 2012 ).
The infected plants develop partial or complete
brilliant golden yellow mosaic on leaves, stunt-
ed growth, less number of pods with reduced
pod size. The rate of transmission of virus with
10 viruliferous whiteflies ( Bemisia tabaci) was
100 % at 24h acquisition and inoculation access,
and latent period for symptom expression was
between 7 and 15 days after inoculation. Single
whitefly per plant could transmit the disease up
to 40 %. (Jyothi et al. 2013 )
Thrips Thrips are small to minute insects with
an adult body size ranging in most species from
about 0.5 to 5 mm and adults usually have four
slender wings. About 5000 species of thrips have
been recognized represents a little over 60 % of
the world total. As plant disease perspective all
known vectors of tospoviruses are only in two
genera of thirps: Franklieniella and Thrips.
Among several thrips, Thrips palmi Karny com-
monly known as melon thrips is believed from
Southeast Asia (Mound 1996 ). T. palmi Karny is
a phytophagous pest, especially of species in the
Cucurbitaceae and Solanaceae, such as sweet
pepper, tobacco, cucumber, watermelon, melon,
squash, and pumpkin and potato. However
other crops such as cotton, cowpea, pea, com-
mon bean, soybean, sunflower, and sesame are
also hosts. T. palmi lifecycle from egg to adult
lasts 17.5 days at 25 °C. The adults emerge from
pupae in the soil and migrate to leaves and flow-
ers of host plants, where they can be found in
pockets, cracks or crevices. Eggs are laid on the
host. The second larva goes into the soil, where
it develops and pupates, thus completing the life
cycle. T. palmi transmits Groundnut Bud Necro-
sis Virus (GBNV) (Vijaylakshmi 1994 ; Wight-
man et al. 1995. In India Adkins et al. ( 2010 )
reported major thrips species viz., T. palmi, T.
tabaci, F. schultzei, Scirtothrips dorsalis and T.
hawaiiensis in crops like tomato, chilli, pepper
and onion.
In Thailand, a new vector of capsicum chlo-
rosis virus, i.e., adult Ceratothripoides claratris
showed 69 % transmission to tomato after acquir-
ing the CaCV (isolate AIT) as freshly emerged
(< 1 h) first-instar larvae. However, when just
molted (< 1 h) second-instar larvae acquired the
virus, the percentage of adult transmitters signifi-
cantly decreased (48 %). The transmission effi-
ciency of up to 47 % was detected with second
instar larvae of C. claratris which had acquired
the virus as freshly emerged first-instar larvae
(Premachandra et al. 2005 ). Transmission effi-
ciency did not significantly differ between adult
males and females, irrespective of the larval
stage at which the virus was acquired. Highest
transmission efficiency for CaCV was recorded
in adult C. claratris derived from second-instar
larvae collected from infected tomato plants in a
greenhouse. Lowest transmission efficiency was
observed in adults directly collected from infect-
ed tomato plants in the greenhouse. The spread of
CaCV on tomato plants in greenhouses showed a
close association with thrips infestations.
Members of the subfamily Deltocephali-
nae include many vector species transmitting
pathogens among economically important crops.
Species of ten genera belonging to seven tribes
namely, Exitianus ball, Nephotettix matsumura,
Deltocephalus Burmeister, Hecalus Stål, Balclu-
tha Kirkaldy, cicadulina China, Hishimonus ishi-
hara, Orosius distant, Changwhania Kwon and
Doratulina melichar were detected in a survey
carried out during 2007–2008 in Mid Country
associated with the vegetable ecosystems of Sri
Lanka. An illustrated dichotomous key based on
the morphology and genitalia characters is pre-