RESISTANCE TO SPODOPTERA-EXIGUA IN APIUM-PROSTRATUM

Two Apium accessions were compared with the commercial cultivar 'Tall Utah' 52-70R (A. graveolens [L.1) for resistance to Spodoptera exigua (Hubner)(Lepidoptera: Noctuidae). Oviposition rate was not significantly different between the three genotypes. In all accessions, eggs were usually placed on the upper half of the plants. Implications of this oviposition pattern on S. exigua management in celery are discussed. The wild species A. prostratum ssp prostratum var filiform (A230) showed a significantly higher resistance to S. exigua than 52-70R. The levels of carcinogenic and mutagenic linear furanocoumarins in the commercial cultivar 52-70R (1.41-mu-g/g in the petioles; 5.85-mu-g/g in the leaves) and in the plant accession A. nodiflorum (5.40-mu-g/g in the petioles; 2.99-mu-g/g in the leaves) were far below the concentration reported to produce acute contact dermatitis (18.0-mu-g/g). The levels of furanocoumarins in A. prostratum petioles (186.14-mu-g/g) and leaves (326.45-mu-g/g) were 10 and 18 times higher, respectively, than the concentration known to cause contact dermatitis. However, resistance in A. prostratum was primarily due to non-preference and the linear furanocoumarins did not induce non-preference. Therefore, the resistance shown by this plant accession does not appear to be furanocoumarin-based and may be suitable for transfer to commercial celery for use in S. exigua management.