none Arrestants which keep Apanteles kariyai in the host habitat were synthesized by Wittig reaction followed by hydrogenation from furan compounds and lead tetraacetate oxidation of alcohols. From the comparison of the analytical data of natural arrestants and synthetic compounds, the natural arrestants appeared to be a mixture of cis- and trans-isomers of 2,5-dialkyltetrahydrofuran. Bioassays results of arresting activity of natural and synthetic compounds showed that cis- and trans-isomers were similar in activity, and 2-alkyltetrahydrofurans had no activity.