The nonpersistent transmission of viruses by aphids
illustrates the importance of how vector transmission
characteristics contribute to the spread of plant disease
and why some control strategies for these viruses differ
from those for other aphid-transmitted viruses. Potato
virus Y (PVY) and other potyviruses are transmitted
by a wide variety of aphids (family Aphididae; Fig. 1)
in a nonpersistent manner (relatively low vector specificity). The optimum time for an aphid to acquire PVY
is after only a few minutes of feeding. The most convincing experimental evidence points to the tips of
the vector stylets (Fig. 2) as the critical region where
the virus is transferred from vector to plant during
feeding. A bridging polypeptide molecule links virus
particles to the aphid’s stylet tips.
[2]
A virus can genetically code for its own linking molecule (‘‘helper
factor’’) or provide a helper factor to aid the aphid
transmission of another virus. How the virus detaches
from the vector mouthparts is not understood.
[3]
The
nonpersistent nature of the transmission of PVY fits
in well with the flight behavior of its aphid vectors to
promote virus spread in crops. Alighting aphids typically make a few probes on the first plant on which