B. Bencharki et al., Assessment of transmission ability of barley yellow dwarf virus-PAV isolates by different populations of Rhopalosiphum padi and Sitobion avenae, EUR J PL P, 106(5), 2000, pp. 455-464
Populations of two aphid species from different geographic regions of Moroc
co were tested for their ability to transmit five barley yellow dwarf virus
-PAV (BYDV-PAV) type isolates using Clintland 64 oat as the test plant. Tra
nsmission efficiencies were determined for 10 sub-populations of Rhopalosip
hum padi and 12 sub-populations of Sitobion avenae. After a short acquisiti
on access period (AAP) of 4 h, all populations transmitted the virus but wi
th different efficiencies. R. padi (Rp-S) and S. avenae (Sa-S) collected in
the Settat region were the most efficient vectors, with transmission rates
of 38% and 27%, respectively. R. padi (Rp-C) collected at Chaouen and S. a
venae (Sa-B) at Berkane, were poor transmitters with respective vectoring a
bilities of 20% and 16%. These four sub-populations were chosen to study th
e acquisition of BYDV-PAV and the retention of virus within aphids in more
detail. The transmission after two AAPs of 4 h and 48 h were compared. Star
ved aphids given a 4 h AAP had significantly higher transmission efficienci
es than non-starved aphids. However, after a 48 h AAP, no difference was ob
served in the transmission between starved and non-starved aphids. Intraspe
cific variability was also detected by means of serial transfers of individ
ual aphids after the given AAP. Following the first day of serial transfers
, no differences were observed in transmission efficiency and virus titers
for sub-populations within each species acquiring the virus during 48 h, bu
t there was significant variation when the virus was acquired in 4 h. The l
evels of PAV antigen retained by aphids fed on healthy plants declined rapi
dly during the first day after acquisition, but remained fairly constant du
ring the next 5-7 days depending on the length of the AAP. Virus antigen co
uld be detected by ELISA in Rp-S and Sa-S for up to 11 days of serial trans
fer, but it was shown that aphids could retain and transmit BYDV-PAV for at
least 3 weeks.