Effects of acetaldehyde on fruit quality and target pest mortality for harvested strawberries

Abstract

Strawberry fruit and western flower thrips were exposed to 1, 2, 3, or 4% acetaldehyde (Aa) for 2 h in air or in 20 kPa CO2. Following treatment, fruit were stored at 0 or 20 8C for 4 or 2 days, respectively. Aa treatment did not significantly impact fruit firmness, color, or soluble solids content; however, calyx damage increased with increasing concentration of Aa. Strawberry fruit tolerated exposure to 1 or 2% Aa with little or no damage to the fruit calyx. Fruit Aa, ethanol, and ethyl acetate concentrations increased initially, but decreased over time; the decrease being greater in fruit stored at 20 8C as compared with 0 8C. Methanol and acetone levels were lower in treated than untreated fruit. Western flower thrips were not completely controlled by any of the treatments, but � /95% mortality was achieved by a 2 h exposure to 3 or 4% Aa. The presence of 20 kPa CO2 enhanced mortality of western flower thrips at lower concentrations of Aa. Strawberry fruit, western flower thrips and two-spotted spider mites were also exposed to multiple applications of Aa over time. Strawberry fruit exposed to low concentrations of Aa in repeated doses showed higher tolerance than fruit exposed to the same dose as a single exposure. While repeated exposure to 1 or 2% Aa resulted in greater pest mortality than a single exposure to 1 or 2% Aa, mortality was significantly lower with repeated applications of low doses as compared with a single application of the accumulated dose (1, 1, 1 Aa vs. 3% Aa). None of the treatments resulted in complete control of either target pest. # 2002 Elsevier Science B.V. All rights reserved.