Effect of Transplantation Date on the Seasonal Abundance of the Green Peach Aphid (Homoptera: Aphididae) and Two Aphid Predators on Flue-Cured Tobacco

Abstract

The effects of flue-cured tobacco transplantation date on the seasonal abundance of the green peach aphid, Myzus persicae (Sulzer), a stilt bug, Jalysus wickhami Van Duzee, and the convergent lady beetle, Hippodamia conoergens Guerin-Memeville, were investigated in south-central Virginia during 1979–1981. Tobacco was transplated ca. 10 days apart on three dates from 10 to 29 May 1979 and on five dates from 28 April to 9 June 1980 and 1981. Aphid populations were highest on the first two transplantings (10 and 20 May) in 1979, the first three (29 April, 9 and 19 May) in 1980, and the third and fourth (18 and 28 May) in 1981. Populations were lowest on late-transplanted tobacco. In 1981, tobacco transplanted on the first two dates matured 14 to 29 days earlier and, thereafter, had lower aphid populations than comparable treatments in 1979 and 1980. Populations usually declined on tobacco after topping (removal of terminal floral branch) was initiated. Lady beetle populations were closely related to aphid abundance in 1980, but the relationship was less distinct in 1981. Stilt bug populations peaked in all trans plantings during the first half of August, and they were significantly more abundant in the last two transplantings than the first three during the last half of August and early September. In 1980 and 1981 yields, returns (dollars per hectare), and values (dollars per kilogram) were similar for the first three trans plantings, but all were significantly reduced in the fourth and fifth transplantings during at least 1 year.