Plant phenolics as dietary antioxidants for herbivorous insects: A test with genetically modified tobacco

Kelly S. Johnson, Gary Felton

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

High foliar phenolics are generally assumed to increase resistance to insect herbivores, but recent studies show that tobacco lines modified to over- and underexpress phenolics do not exhibit higher constitutive resistance to caterpillars. This is contrary to the expectation that ingestion of tobacco phenolics, particularly chlorogenic acid, should cause oxidative stress in herbivores. We investigated free radical production and antioxidant capacity of fresh crushed leaves of tobacco lines exhibiting over a sixfold difference in chlorogenic acid content to test whether high phenolic concentrations are associated with increased production of reactive oxygen species (ROS). The effects of in planta phenolic levels on feeding behavior, growth, biochemical markers of oxidative stress, and the antioxidant capacity of midgut fluid and hemolymph were assessed in tobacco budworm, Heliothis virescens. The experiments showed that high phenolic foliage was more prooxidant than low phenolic foliage, but the net balance in crushed tissue was antioxidant in comparison to buffer and the commercial antioxidant standard, Trolox. In H. virescens, the antioxidant capacity of midgut fluid was also powerful, and caterpillars fed high phenolic foliage did not exhibit the expected markers of oxidative stress in midgut tissues (altered ascorbate ratios, disulfides, or total hydroperoxides). Instead, hemolymph of larvae fed high phenolic foliage exhibited improved total Trolox equivalent antioxidant capacity (TEAC). These results suggest that the elevated foliar phenolics in some plants may have beneficial antioxidant properties for herbivorous insects, much as dietary phenolics do in mammals.

Original languageEnglish (US)
Pages (from-to)2579-2597
Number of pages19
JournalJournal of Chemical Ecology
Volume27
Issue number12
DOIs
StatePublished - Dec 1 2001

Fingerprint

Tobacco
phytophagous insects
tobacco
antioxidant
Insects
Antioxidants
insect
antioxidants
foliage
Oxidative stress
Heliothis virescens
midgut
Chlorogenic Acid
testing
Herbivory
Oxidative Stress
oxidative stress
Hemolymph
caterpillar
leaves

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry

Cite this

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Plant phenolics as dietary antioxidants for herbivorous insects : A test with genetically modified tobacco. / Johnson, Kelly S.; Felton, Gary.

In: Journal of Chemical Ecology, Vol. 27, No. 12, 01.12.2001, p. 2579-2597.

Research output: Contribution to journalArticle

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