Effects of plant gross morphology on predator consumption rates.
We find that spatial structure, and in particular, differences in gross plant morphology, can alter the consumption rates of generalist insect predators. We compared Asian lady beetle, Harmonia axyridis Pallas, and green lacewing larvae, Chrysoperla carnea Stephens, consumption rates  of pea aphids, Acyrthosiphon pisum Harris, in homogeneous environments (petri dishes) and heterogeneous environments (whole plants). Spatial complexity is often described as reducing predator success, and we did find that predators consumed significantly more aphids on leaf tissue in petri  dishes than on whole plants with the same surface area. However, subtle differences in plant morphology may have more unexpected effects. A comparison of consumption rates on four different isogenic pea morphs (Pisum sativum L.) controlled for surface area indicated that both lady beetles  and lacewings were more successful on morphologies that were highly branched. We speculate that predators move more easily over highly branched plants because there are more edges to grasp.
Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
Paula G
PG
Reynolds
Kim
K
Cuddington
D000818:Animals; D001042:Aphids / Q000502:physiology; D001517:Coleoptera / Q000502:physiology; D004777:Environment; D005247:Feeding Behavior; D020387:Food Chain; D007313:Insecta / Q000502:physiology*; D018532:Pisum sativum / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development; D010572:Pest Control, Biological; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D011156:Population Density; D013045:Species Specificity