Acyrthosiphon pisum (Harris) became highly inoculative after partially purified and density gradient-purified preparations of pea enation mosaic virus (PEMV) were injected into them as young nymphs. The aphids' mean rate of transmission, Vo , and mean (weighted) period of inoculativity, Tt , increased linearly as the dosage of injected virus increased, whereas the median latent period, LP50, decreased as dosage increased. When late 1st to early 2nd instars were inoculated with partially purified virus preparations at a concentration of A260nm = 30, a Vo of 21 transmissions per aphid per generation, a Tt of 9.35 days, and an LP50 as short as 3.0 hours were realized. All attempts to maintain inoculativity among aphid lines by the serial hemolymph-passage method failed after the 2nd passage, even though young nymphs were used as recipients in each passage. Inoculativity was maintained in over 60% of the aphid lines after the 1st passage. Aphid nymphs became inoculative when injected with hemolymph collected from aphids 4, 7, and 10 days after a 24-hour acquisition-access period on PEMV-infected plants but not when injected with hemolymph collected on the 13th day.

Journal Article Regurgitation by Myzus persicae during Membrane Feeding: Its Likely Function in Transmission of Nonpersistent Plant Viruses Get access Kerry F. Harris, Kerry F. Harris Department of Entomology, Michigan State University, East Lansing 48823. Search for other works by this author on: Oxford Academic Google Scholar James E. Bath James E. Bath Department of Entomology, Michigan State University, East Lansing 48823. Search for other works by this author on: Oxford Academic Google Scholar Annals of the Entomological Society of America, Volume 66, Issue 4, 16 July 1973, Pages 793–796, https://doi.org/10.1093/aesa/66.4.793 Published: 16 July 1973 Article history Received: 20 November 1972 Published: 16 July 1973

Tests were conducted to determine the influence of temperature differences, preinoculation starvation, inoculation probing times, and inoculation probing sites on the ability of the pea aphid, Acyrthosiphon pisum (Harris), to transmit pea enation mosaic virus (PEMV), a virus which possesses a circulative relationship with the vector. Aphids subjected to temperatures of 10°:10°C (10°C during a 24-hour acquisition access period and 10°C during the subsequent latent and inoculation probing periods) required a mean latent period (LP50) of 98.3 hours whereas those subjected to a 10°:20°C regime needed only a 45-hour LP50. Treatments of 20°:20°; 30° :20°; and 30°:30°C caused LP50 values of much less than 48 hours. Nearly all aphids, regardless of treatment, transmitted virus at least once during a week-long series of daily transfers to healthy plants; however, insects from the 30°:30°C group transmitted virus to significantly fewer plants during either 2-minute or 4-hour inoculation periods 7 days after virus acquisition than did aphids from any of the other treatments. Inoculative aphids that were starved for 4–8 hours prior to a 2-minute inoculation probing period (IPP) transmitted PEMV with significantly higher efficiency (83.7%) than did aphids starved for 16–20 hours (68.9%). Aphids starved 0–2 hours were intermediate in transmission efficiency (75.1%). Transmission efficiency during IPPs of 1, 5, and 10 min at various sites on garden pea, Pisum sativum L., seedlings in the 1-leaf stage and at random on plants in the preleaf stage was tested. Inoculation to the preleaf stage resulted in a mean transmission efficiency of 71.7%, data pooled from all IPPs, and transmission to this stage was significantly higher than to any of the sites tested (the ab- and adaxial surface of leaf and petiole, the stem, and the terminal bud) on the 1-leaf-stage plants, which ranged in pooled transmission efficiency from 17.5 to 42.7%. Significant differences were not detected on transmission in the average effect of IPP, pooled from all probing sites. Transmission to the youngest leaf on a pea seedling in the 2-leaf stage was significantly higher (36%) than to the other leaf (27%). Twenty-four-hour temperature treatments of 10°, 20°, and 30°C to inoculative pea aphids prior to a 1-min IPP had no significant effect on mean transmission efficiency; however, the 20°C treatment resulted in highest efficiency (60.9%). The length of salivary sheath deposited by aphids during 1-, 5-, and 10-minute probes on the ab- and adaxial surface of the petiole on 1-leaf-stage plants and on the stem of preleaf and 1-leaf plants was studied. No significance was detected among length of sheath deposited in any tissue. Thus, differences in transmission efficiency to these sites are not related to length of sheath. As expected, the average length of sheath produced during the 3 IPPs regardless of probing site were significantly different from one another (1 minute = 0.37 mm; 5 minutes = 1.16 mm; 10 minutes = 1.78 mm). Postinoculation temperature was found to influence symptom development. Only 30% of pea seedlings held in a greenhouse at 30–44°C after being probed for 2 minutes by inoculative aphids developed symptoms, whereas 67% of those held at 24–30°C became infected.