Differential Aphid Transmission of Two Bean Yellow Mosaic Virus Strains and Comparative Transmission by Biotypes and Stages of the Pea Aphid1, 2

Abstract

Two strains of bean yellow mosaic virus (BYMV) were compared as to (1) transmissibility by Acyrthosiphon pisum (Harris) and Myzus persicae (Sulzer) (Homoptera: Aphididae) and (2) effects on selected herbaceous host plants. A strain from Michigan (Mich BYMV) was not transmissible by A. pisum in 1200 trials with single aphids even though various instars of 2 biotypes, 1 to 15-minute acquisition-probing periods, 2 source plant species, and various probing sites were used. M. persicae adults did not transmit Mich BYMV in 88 trials; nymphs were not tested. A strain from Oregon (Ore IV BYMV) was transmitted with about 50% efficiency by 1st instars of A. pisum (Biotype EL) and by adult M. pcrsicac following 1 to 10-minute acquisition-probing periods. Three A. pisum biotypes (EL, EL, and WARF) that were isolated on the basis of their efficiency (EL and EL1: efficient; WARF: inefficient) in transmitting peaenation mosaic virus (PEMV) were compared as vectors of Ore IV BYMV. Adults of El1 and WARF were unable to transmit virus whereas adults of EL were 29.0 and 19.8% efficient after 1- and 5-minute acquisition-probing periods, respectively. Maximum transmission by 1st instars after either probing period was: EL 49.5%, EL, 7.6%, and WARF 15.2%. Thus, Biotypes EL and WARF have transmitted both a circulative virus (PEMV) and a stylet-borne virus (BYMV) with the same relative transmission efficiency whereas EL1 was an efficient vector of PEMV and a poor vector of BYMV. First instars of Biotype EL transmitted Ore IV BYMV with significantly greater ( P = <0.05) efficiency after 1- and 5-minute acquisitionprobing periods than did adults. A differential host reaction occurred on Phascolus vulgaris L. when plants were mechanically inoculated with the 2 virus strains. Typical brilliant yellow mosaic symptoms were produced in response to Mich BYMV infection whereas only moderate chlorotic spotting was induced by Ore IV BYMV.