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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.

1 The attractiveness of pitfall traps baited with a synthetic host volatile attractant to colonizing adult Colorado potato beetle, Leptinotarsa decemlineata (Say) was evaluated in a field setting. 2 Significantly more postdiapause, colonizing adult L. decemlineata were captured in baited than unbaited pitfall traps. 3 The potential for this synthetic kairomone to enhance the efficacy of trap cropping as a management tool was evaluated by comparing conventionally managed plots with like-sized plots bordered by either attractant-treated trap crop or untreated trap crop. 4 More postdiapause, colonizing adults, egg masses and small larvae were present in attractant-treated trap crops than in untreated trap crops. 5 There were no significant differences in egg mass and small larvae densities between plots bordered by attractant-treated trap crops and conventionally managed plots, but there were significantly fewer large larvae and adult beetles in conventionally managed plots. 6 Plant canopy area of conventionally managed plots was significantly greater than in plots bordered by either type of trap crop. 7 Yields for conventionally managed plots and plots bordered by attractanttreated trap crops did not differ, and less insecticide (44%) was applied to plots bordered by attractant-treated trap crops.

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