EVALUATION OF NATURAL-PRODUCTS AS ANTIFEEDANTS FOR THE PALES WEEVIL (COLEOPTERA, CURCULIONIDE) AND AS FUNGITOXINS FOR LEPTOGRAPHIUM-PROCERUM

Four natural plant compounds (limonin, S (+) and R (-) carvone, and cu curbitacin) and one insect pheromone (verbenone) were evaluated for an tifeedant activity against the pales weevil, Hylobius pales (Herbst), on Pinus strobus seedlings and for toxic activity against the pathogen ic fungus, Leptographium procerum (Kendrick) Wingfield, which is vecto red by H. pales to P. strobus. All compounds demonstrated significant antifeedant activity in a choice test on treated pine seedlings, but n one completely eliminated feeding. Only cucurbitacin elicited a linear dose-response relationship, with significant activity occurring at co ncentrations as low as 0.10 mu g/ml. The other compounds significantly reduced feeding at concentrations as low as 1 mu g/ml (the lowest con centration at which they were tested). Total feeding activity was unaf fected for all but one treatment (S (+) carvone at 1 mu g/ml) when com pared with feeding on the untreated control seedlings. It is, therefor e, unlikely that the compounds in this study were toxic to the weevils during the 2 d evaluation period. In the fungitoxin test, all compoun ds except cucurbitacin suppressed germination oft. procerum spores. R (-) carvone was the most effective, allowing only 5% germination at 1 mu g/ml, compared to 96% germination in the water solvent.