Efficiency of Three Aphid Species in the Transmission of Pea Enation Mosaic Virus1

Abstract

The relative efliciencies of pea enation mosaic virus (PEMV) acquisition by the pea aphid, Acyrthosiphon pisum (Harris), the potato aphid, Macrosiphum euphorbiae (Thomas), and the green peach aphid, Myzus persicae . (Sul/er), were obtained through the use of 2 to 4 strains per species. No significant differences in acquisition emciency were detected in 2 M . persicae or 3 Macrosiphum euphorbiae strains, but 4 A. pisllm strains were split into 3 signifkantly different efficiency groups. The most efficient pea aphid strain was 10 and 53.7% efficient after acquisition access probing periods of 1 hour and 24 hours, respectively; the poorest strain had corresponding values of 3.3 and 13%. Myzus persicae had an acquisition threshold of 0.5 hour or less whereas Macrosiphum euphorbiae and A. pisum thresholds were 0.5-1 hour and 1 hour or less, respectively. The pooled data Erom all test strains ranked the 3 species in the following order of descending efficiency: Myzus persicae, Macrosiphum euphorbiae , and A. pisum . Inoculation trials with an aphid strain which was highly efficient in PEMV acquisition revealed that A. pisum and M. euphorbiae were capable of virus inoculations to pea in 1 min or less; Myzus persicae required 5 minutes or less, but too few trials were conducted at 1 minute to rule it out. Increases in inoculation probing time from 15 to 60 minutes had little or no effect on A. pisum and M. persicae , whereas Macrosiphum euphorbiae efficiency increased exponentially.