PHTHALIDE-BASED HOST-PLANT RESISTANCE TO SPODOPTERA-EXIGUA AND TRICHOPLUSIA NI IN APIUM-GRAVEOLENS

A chemical basis for the difference in suitability between two celeria c (Apium graveolens var. rapaceum) cultivars for the survival and grow th of Spodoptera exigua (Hubner) and Trichoplusia ni (Hubner) was iden tified as sedanenolide (3-n-butyl-4,5-dihydro-isobenzofuranone). Sedan enolide was isolated using a bioassay-driven extraction and purificati on procedure and was identified using several spectrometric methods. F oliar concentrations of sedanenolide were negatively correlated with l arval performance and were significantly higher in the cultivar less s uitable for larval survival and growth. Sedanenolide and Bacillus thur ingiensis Berliner acted additively in reducing larval growth when com bined in artificial diets, a result that is consistent with previous s tudies in which the combined effect of host plant cultivar and B. thur ingiensis on larval survival and growth were additive.