Nonpersistent Virus Transmission Efficiency Determined by Aphid Probing Behavior during Intracellular Punctures

Abstract

The probing behavior of starved and nonstarved Myzus persicae (Sulzer) on pepper plants was compared using the electrical penetration graph technique. Special attention was paid to the 1st intracellular puncture produced by the aphids, recorded as a potential drop waveform pattern. Previously fasted aphids produced potential drops with a longer phase II3 (3.6 versus 2.5 s), and typical II3 pulses were clearly visible in 89% of the records (versus only 61% for the nonstarved aphids). This ability of starved aphids to produce potential drops with a long phase II3 and its associated II3 pulses may account for the increase in potato virus Y (PVY) transmission efficiency when compared with nonstarved aphids (57 versus 4%). A new explanation to the "preacquisition starvation effect" is proposed based on our results. In a separate experiment, the early probing behavior of different aphid species [M. pensicae, Aphis gossypii Glover, Rhopalosiphum padi (L.), and Sitobion avenae (F.)] on pepper plants was compared. Again, the great variability observed in the morphology and duration of phase II3 of the potential drops could be correlated with differences in transmission efficiences. Individuals from species that transmitted PVY efficiently (M. persicae and A gossypii) usually produced pds with long II3 phases and clear II3 pulses, whereas inefficient vectors (R. padi and S. avenae) showed short II3 phases and in many cases absence of II3 pulses. The implications of these findings for host-plant recognition and virus-vector specificity is discussed.