Depression of a Coccinellid Functional Response to an Aphid by Sequestered Plant Chemical Defenses
Loading...
Authors
Blaauw, Brett R.
Issue Date
2005
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
The three trophic levels of plants, herbivores, and predators have complex effects on one another. Both "bottom/up" processes generated by plant chemical defenses and "top/down" effects mediated by predator foraging behaviors are important and herbivores act as the conduit for variable dynamics among these
interactions between defense and foraging. For example, some specialized
herbivores, such as oleander aphids, Aphis nerii, are able to sequester plant defense
chemicals for their own defense against predators. A. nerii sequesters cardenolides
that are produced by the milkweed host plants and use these chemicals in their own
defense against predators, such as coccinellids. I investigated whether aphids possess
the ability to defend against coccinellid predators when feeding from the milkweed
Asclepias curassavica that contains inducible levels of cardenolides. To answer this
question, I observed the functional response of Harmonia axyridis, know as the Asian
lady bird beetle, as it interacted with two different aphid species: the ardenolide-sequestering A. nerii and Myzus persicae taken from a cardenolide-deficient plant as a
control. A. nerii showed significant defense against the predator through the
expression of a depressed type II predator functional response in comparison to that
generated by the palatable M. persicae. Handling time of A. nerii was longer, and H.
axyridis ate fewer of these aphids, further indicating that the sequestered chemical
defense of A. nerii is effective against aphidophagous predators.
Description
vi, 28 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.