Environmental Entomology (1994) 23, 937-942

Sanford D. Eigenbrode and John T. Trumble (1994)
Fruit-based tolerance to damage by beet armyworm (Lepidoptera: Noctuidae) in tomato
Environmental Entomology 23 (4), 937-942
Abstract: Damage to fruit of eight accessions and cultivated varieties of tomato by natural infestations of beet armyworm, Spodoptera exigua (Hübner), in Southern California ranged from 0.1 to 10%. This field damage was significantly correlated with 9-d weight and survival of S. exigua larvae reared to pupation from third instar in the laboratory on fruit of these tomato test entries. Two accessions of Lycopersicon esculentum variety cerasiforme and one small-fruited cultivated variety of L. esculentum sustained lowest damage in the field (1-50% of susceptible controls). S. exigua larvae had reduced survival and reduced 9-d weight (~20% of susceptible controls). Time to pupation was also increased on these three lines (30% greater than controls). The resistant fruits had high concentrations of total glycoalkaloids in the fruit tissue (5.4 to 25.4 mg/g dry weight versus 1.8 mg/g in a susceptible fruit) and this may have been the basis of the antibiosis. Phytosterol concentrations in the fruits were not sufficiently high to potentially alleviate glycoalkaloid toxicity. In binary choice tests between fruit and foliage of the most resistant line, L. esculentum variety cerasiforme LA 1320, larvae of S. exigua fed on fruit 70% less than larvae in choice tests between the fruit and foliage of susceptible 'VFN 7718'. Larval nonpreference for fruit apparently contributes to resistance in LA 1320. The resistance to S. exigua, of LA 1320 predicted by this mechanism, is close to observed levels of resistance in the field.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): John T. Trumble, Sanford D. Eigenbrode

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera exigua	Tomato (Solanum lycopersicum)	U.S.A. (SW)