Predation upon the oblique-banded leafroller, Choristoneura rosaceana (Lepidoptera : Tortricidae), by two aphidophagous coccinellids (Coleoptera : Coccinellidae) in the presence and absence of aphids

摘要

Our goal has been to determine the effect of the presence of aphids oil voracity (measured as number of prey eaten and biomass consumed) of Coccinella septempunctata L. and Hormonia axyridis Pallas (Coleoptera: Coccinellidae) feeding upon the oblique-banded leafroller, Choristoneura rosaceano (Harris) (Lepidoptera: Tortricidae). For each coccinellid predator, treatments Using a single prey species, with either 30 first instar C. rosaceana or 100 third instars Aphis pomi DeGeer (Hemiptera: Aphididae), were compared with two-prey treatments in which the two prey species were present simultaneously. For both predators, the total number of prey killed (total prey species pooled) and the total biomass consumed were significantly higher when both prey were present than in single-prey treatments. The voracity of C. septempunctata on C. rosaceana larvae was not affected by adding A. pomi, whereas that of H. axyridis declined; the voracity of both predators on A. pomi increased when C. rosaceana larvae were added. The preference for the aphids over C. rosaceana was confirmed for both coccinellid species.