Roles of food quality and enemy-free space in host use by a generalist insect herbivore

Michael S. Singer, Daniela Rodrigues, John O. Stireman, Yves Carrière

Research output: Contribution to journalArticle

95 Scopus citations

Abstract

The relative importance of food quality vs. enemy-free space remains an unresolved but central issue in the evolutionary ecology of host use by phytophagous insects. In this study, we investigate their relative importance in determining host-plant use by a generalist caterpillar, Estigmene acrea (Lepidoptera: Arctiidae). In nature, E. acrea late-instar caterpillars preferred Senecio longilobus (Asteraceae), which contains pyrrolizidine alkaloids that the caterpillars sequester, over Viguiera dentata (Asteraceae), a natal host, and typically suffered a 28% mortality risk from parasitoids. We hypothesized that the natural, mixed diet of caterpillars provides high-quality food via hosts like Viguiera as well as antiparasitoid defense via sequestered toxins from Senecio. We found that a pure Viguiera diet provides superior growth performance over a pure Senecio or mixed diet in the absence of parasitism. However, when parasitism risk is at least moderate, the mixed diet provides a survival advantage over the pure diets of Viguiera or Senecio. We therefore conclude that the balance between benefits of growth (food quality) and defense (enemy-free space) maintains the use of a mixed diet in nature. Furthermore, the value of enemy-free space supercedes the value of food quality in determining the host-plant preference of late-instar caterpillars.

Original languageEnglish (US)
Pages (from-to)2747-2753
Number of pages7
JournalEcology
Volume85
Issue number10
DOIs
StatePublished - Oct 2004

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Keywords

  • Arctiidae
  • Diet choice
  • Enemy-free space
  • Estigmene acrea
  • Generalist insect herbivore
  • Host preference
  • Parasitoids
  • Polyphagy
  • Senecio longilobus
  • Tachinidae
  • Tritrophic interactions
  • Viguiera dentata

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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