Soybean leaf pubescence affects aphid vector transmission and field spread of soybean mosaic virus

Abstract
SUMMARY: A study was undertaken to determine the influence of trichome density on the spread of non‐persistently transmitted plant viruses by aphid vectors. A system using soybean plants and soybean mosaic virus (SMV) tested the hypothesis that greater leaf trichome density inhibits probing activity of vector species, leading to reduced virus spread and retarded virus epidemics under field conditions.Probing activity of three important aphid vectors of SMV, Myzus persicae, Rhopalosiphum maidis, and Aphis citricola, was affected by the density of soybean leaf trichomes. Less pubescent and glabrous isolines elicited greater probing activity than did densely pubescent isolines. Among the parameters considered, probe duration was found to be species specific, whereas the following traits were consistent among species for the denser isolines: reduced numbers of probes, greater length of time to first probe, and less time spent probing. Laboratory transmission of soybean mosaic virus was reduced in the more densely pubescent isolines by the vector species tested.Field spread of SMV was negatively correlated with density of pubescence. In our system, we found that denser leaf pubescence retards field epidemics of non‐persistently transmitted plant viruses.