Floral affinity and benefits of dietary mixing with flowers for a polyphagous scarab, Popillia japonica Newman

David W. Held, Daniel A. Potter

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Many generalist herbivores, especially adult beetles, are facultative florivores, feeding on leaves but readily accepting floral tissues when available. We speculated that day-flying beetles with high energetic requirements would benefit from dietary mixing with nutrient-rich flower tissues and favor them during foraging. We tested that "Floral Affinity Hypothesis" with Popillia japonica, a day-active ruteline scarab that feeds intermittently throughout its adult life on multiple plant species. In field tests with six species of flowering hosts, far more landings occurred on flowers than on foliage for all plants except Hibiscus syriacus which bears flowers along the main stem rather than terminally. Trials with elevated plants showed that height of the floral display contributes to beetles' landing on flowers. Flower petals generally were preferred over leaves in laboratory choice tests. Nitrogen and water content were comparable or higher in foliage than in petals, but plant sugars were much higher in petals. Longevity and fecundity of beetles provided single-plant diets of Hibiscus, Rosa x hybrida, or Trifolium flowers for 3 weeks were as high, or higher, than for beetles fed foliage of Tilia cordata, a highly suitable resource. As expected, rotating flowers or Tilia foliage with marginally suitable Quercus palustris foliage enhanced those parameters relative to a diet of Quercus alone, but beetles provided high-quality Tilia foliage also benefitted from dietary mixing with flowers. Nearly all past dietary mixing studies concerned immature insects, for which growth rate is paramount. Opportunistic florivory by adult beetles represents a type of dietary mixing wherein the premium may be calorie-rich food for fueling flight muscles, with ensuing reproductive benefits.

Original languageEnglish
Pages (from-to)312-320
Number of pages9
Issue number2
StatePublished - Jul 2004

Bibliographical note

Funding Information:
Acknowledgements We thank C. Prater, M. Cummings, J. Hubbard, and M. Rogers for technical assistance. Thanks to R. Bessin, J. Buxton, K. Haynes, D. Wise (University of Kentucky) and two anonymous reviewers for suggestions that greatly improved the manuscript. Plants were donated by Bear Creek Gardens (Medford, Ore., USA) and Greenleaf Nursery (Park Hill, Okla., USA). Funding, in part, was provided through a grant from the University of Kentucky Nursery and Landscape Endowment Fund. This paper is No. 03-08-114 of the University of Kentucky Experiment Station.


  • Dietary mixing
  • Floral affinity hypothesis
  • Flower-feeding
  • Optimal foraging

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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