Effect of ethanol vapor treatments on lightbrown apple moth larval mortality and ‘Braeburn’ apple fruit characterization

Abstract

Apples infested with 5th instar lightbrown apple moth larvae, Epiphyas postvittana (Walker), were exposed to ethanol vapor treatments at ambient (20 °C) and at low-temperatures (0.5 °C). The most effective ambient treatment was a 7 day exposure to ethanol vapor from a 15% stock solution (generating ≈2.439×107 mg/m3 ethanol) resulting in 87% E. postvittana mortality. At low-temperature complete kill of E. postvittana was achieved after a 12-day exposure to ethanol vapor from a 40% stock solution (≈1.149×107 mg/m3 ethanol). A 12-day exposure to low-temperature only, resulted in 31% mortality. Estimated time for 99% mortality was 7.2 and 17.5 days when ethanol stock solutions of 40 and 20% were used in combination with low-temperature. No significant damage was observed in ‘Braeburn’ apples exposed to low-temperature ethanol vapor treatments over two growing seasons. However, the amount of ethanol, acetaldehyde and ethyl acetate in the apple tissue did increase with increasing ethanol vapor and with longer treatment duration. An ethanolic odor was associated with apples treated for 7 days or more. A 4-week cold storage period following low-temperature ethanol vapor treatment did not result in a reduction in ethanolic odor in fruit.