PHENOLOGY OF THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS) IN ALBERTA

Abstract

Differences in phenology were observed between two populations of Ostrinia nubilalis (Hbn.) in Alberta. In the South Saskatchewan River valley, borers pupated and emerged 3–6 days earlier than on the plains. This was not simply a function of different microclimates because median pupation occurred at 331 degree-days (DD) for plains populations and at 490 DD for valley populations. First-generation flight extended from the last week in June until the 1st week in August. Flight peaks in 1983 occurred on 8 July in the valley and on 14 July on the plains. Flight was delayed in 1984 by cold nightly temperatures. In 1983 valley populations had a partial second generation, with a flight peak in late August. Mean pupal mass was significantly less for plains populations than valley populations. Transplant experiments demonstrated that these differences reflected mainly environmental influences. During spring 1984, mean larval mass in the two populations did not differ until early June, when both mean wet and dry mass of valley larvae increased significantly but those of plains larvae did not change. This variability of phenotypes contributes to the colonizing ability of the European corn borer.

INUNDATIVE RELEASE OF TRICHOGRAMMA BRASSICAE BEZDENKO (HYMENOPTERA: TRICHOGRAMMATIDAE) FOR CONTROL OF EUROPEAN CORN BORER IN SWEET CORN

“…However, the variation in date of moth appearance among the three fields was considerable, with a range of 12 days for the first capture and 14 days for 50% catch. Lee and Spence (1986) also reported a considerable difference in the DD required for postdiapause development and phenology at two different sites at Medicine Hat (about 100 km east of Taber). The phenology of the Alberta population of European corn borer appears to be variable, and this variation among fields reduces the usefulness of a temperature-driven model to predict key events such as peak moth abundance (Kelker et al 1990).…”

DEVELOPMENTAL ADAPTATION OF THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS HÜBNER) IN ALBERTA

“…Thus, we observed a larger partial second generation in valley populations in 1983 than we saw for plains borers (Lee and Spence 1986). Faster development of valley borers during the 5th instar leads to maturation before the arrival of the critical photoperiod, and thus to pupation.…”

“…Rate of development for post-diapause pupation was linearly related to temperature between 17 and 30°C. The value of K for post-diapause pupation of valley corn borers (272 DD, Table 1) was much less than that calculated from field data (490 DD, Lee and Spence 1986), possibly because of post-diapause feeding in the field (Lee and Spence 1986). Slopes of the regression lines were equal (P = 0.19).…”

“…Although rates of development and developmental thresholds have been measured (Caffrey and Worthley 1927;Matteson and Decker 1965;Anderson et al 1982a, 19826;Beck 1983), few studies have compared growth thresholds for different life stages or populations of 0 . Lee and Spence (1986) found distinct phenological differences between newly established populations of corn borers in southeastern Alberta. Lee and Spence (1986) found distinct phenological differences between newly established populations of corn borers in southeastern Alberta.…”

“…Larvae that had not pupated after ca. These were compared with data gathered in field studies of phenology (Lee and Spence 1986). Polyester fabric wrapped around the containers inhibited larval movement.…”