PROBLEM TO BE SOLVED: To provide a new resistant derivative effective for pests causing feeding damage and useful as a pest control agent, and a pest control method for plants using the resistant derivative.SOLUTION: A pest-resistant derivative containing loliolide, epiloliolide or these mixture as an active substance the pest-resistant derivative deriving resistance for Arguloida insects or spider mites a pest control method for plants making contact or absorb a plant body either of the pest-resistant derivative mentioned above the pest control method for plants mentioned above preventing the Arguloida insects or spider mites and either of the pest control method mentioned above that the plant body is a solanaceous plant or a cruciferous plant.
