Knowledge of how individual organisms behave in their environment can provide
a greater understanding of population dynamics. In a predator-prey system, the choices
made by predators when foraging for prey are important aspects of behavior. Particularly
in the case of a stage-structured prey population, how the predator selects prey stages
once a prey patch has been located can have implications for prey population growth,
predator development and fecundity, and predator-prey system dynamics.
Predaceous mites of the family Phytoseiidae are important biological control
agents of Tetranychus spider mites in agricultural settings worldwide. Phytoseiid species
range from specialists that require Tetranychus spider mite prey in order to develop and
reproduce to generalist omnivores. In studies with 13 phytoseiid species, specialized
species tended to prefer T. urticae eggs as prey or have no prey-stage preference while
more generalist species tended to have no prey-stage preference or prey more often on
mobile immatures. Further testing with a subset of these species suggested variability
among species with regard to genetic and environmental influences on prey-stage
preference. The specialist Phytoseiulus persimilis also preferred to forage and oviposit in
patches containing egg-biased stage distributions rather than in adjacent mobile
immature-biased patches. No benefits to offspring developing in either type of patch
were found in terms of developmental time or subsequent adult fecundity. However, the
results of both manipulative experiments and nonlinear population models indicated
potential benefits of egg-biased predation in terms of current adult female fecundity, a
less severe impact of predation on the prey population, and an increased number of
predator descendents during the predator-prey interaction. Considering both subjective
factors and discriminant analyses, prey-stage preference performed well as an indicator
for the ecological classification of phytoseiid species. The classifications of four
phytoseiid species occurring on apple in central and eastern Oregon, USA, were
evaluated accordingly. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29973 |
| Date | 31 October 2003 |
| Creators | Blackwood, J. Scott |
| Contributors | Croft, Brian A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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