Interactions between an introduced and indigenous coccinellid species at different prey densities

John J. Obrycki, Kristopher L. Giles, Andrew M. Ormord

Research output: Contribution to journalArticlepeer-review

117 Scopus citations


Coccinella septempunctata L. (Coleoptera: Coccinellidae), a Palearctic coccinellid, has established and rapidly spread throughout the United States. This quantitative examination of larval interactions between C. septempunctata and Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae), a Nearctic coccinellid, was conducted under controlled prey densities. Larvae of both coccinellid species are affected by a limited diet [one pea aphid per day Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)] compared with an excess diet (> 20 aphids per day). Larval survival decreased from 86 to 63% in C. maculata and from 84 to 33% in C. septempunctata; mean preimaginal developmental time increased from 20.6 to 26.7 days in C. maculata, and from 18.1 to 32.0 days in C. setempunctata. Additionally, on one aphid per day, mean adult weight was reduced from 12.39 to 9.79 mg in C. maculata, and from 39.57 to 14.44 mg in C. septempunctata. Interspecific interactions, favoring C. septempunctata over C. maculata at a low prey density (one aphid per day), take the form of reduced survival of C. maculata compared with C. septempunctata (14 versus 66%). Reduced survival of C. maculata may be the result of competition for aphids or intraguild predation by C. septempunctata on C. maculata. No interspecific interactions (measured as effects on larval survival, preimaginal developmental time, and adult weight) were observed between larvae of these two species at a high prey density (> 20 aphids per predator per day).

Original languageEnglish
Pages (from-to)279-285
Number of pages7
Issue number1-2
StatePublished - 1998

Bibliographical note

Funding Information:
Acknowledgments We thank C. Cook, T. Cortilet, and K. Price of Iowa State University for technical assistance, and P.N. Hinz of Iowa State University for statistical assistance. We thank L.P. Pedigo, Department of Entomology and W.R. Clark, Department of Animal Ecology, Iowa State University for their critical review of an early version of this manuscript. This research was supported by USDA NRI Grant 90-37250-5357 and the Leopold Center for Sustainable Agriculture. This is Journal Paper no. J-16543 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project no. 2755.


  • Biological control
  • Coccinellidae
  • Competition
  • Interspecific interactions
  • Intraguild predation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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