Abstract:

To compare differences in insecticidal activities of tutin and its derivatives (1, 2, 3) on Mythimna separate (Walker), the antifeedant activities of these four compounds were analyzed by using the non-choice leaf disk method. The variations of the esterase activity, two protective enzyme activities, and the total soluble sugar content of M. separate treated with sublethal dose (2.0 mg·mL^-1) of tutin and its derivatives within 48 h were determined using colorimetric method. After tutin was restructured, the antifeedant activities of three derivatives were significantly increased within 48 h, and their activity ranked as: derivative 2 > 3 > 1 > tutin. Treated with tutin, derivative 1, and derivative 3, the esterase activity and total soluble sugar content of M. separate increased slightly, and the protective enzyme activity did not significantly change. Under the treatment of derivative 2, the esterase activity, total soluble sugar content, and SOD activity of the tested larvae presented pronounced increases. It was concluded that the acylation and addition reaction at 2-hydroxyl of tutin could significantly enhance the antifeedant activity, and as a result, derivative 2 was considered as the best compound in terms of the antifeedant activity in this study.

Key words: tutin, derivative, Mythimna separate, antifeedant activity, physiological parameter