| Abstract: | ABSTRACT Limonin and its five derivatives were evaluated in feeding bioassays for depression effects on feeding, growth and development of the fourth stadium Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Epilimonol and limonin diosphenol were most effective in depression of feeding and growth, with ED50s 10 and 8 μg/cm2. At a dosage of 31.6 μg/cm2, epilimonol, limonin diosphenol and limonin caused both significant feeding reduction and developmental delay, while deoxylimonol, tetrahydrolimonin and limonol were not effective. Mouth-part coating and antifeedant bioassays show that feeding inhibition at host acceptance level seems to be the primary mode of action of epilimonol and limonin diosphenol. |
