PARENT SESSION
Contributed Oral Session 112: Evolutionary Ecology: Invasion Dynamics; Populations; Communities
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 514 A, Level 5, Palais des congrès de Montréal
Resource pulses, spatial heterogeneity and the population dynamics of an insect host-parasitoid interaction.
Sait, Steven*,1, Wearing, Helen2, Rohani, Pej2, 1 University of Leeds, Leeds, UK2 University of Georgia, Athens, USA
ABSTRACT- Infrequent resource pulses in nature can have a significant impact on the generalist consumers that can exploit those resources, as well as on community dynamics and structure as a whole. We consider the impact of periodic resource pulses on a laboratory interaction between an insect host and a specialist parasitoid and show that the cyclical behaviour of both the prey and the predator are sensitive to the frequency at which the host is provided with its basal resource. Previous long-term time series of the host, Plodia interpunctella, and the parasitoid, Venturia canescens, exhibit cycles with a period of approximately one host generation. When the resource pulse frequency is decreased by providing a smaller patch of food for the host larval stages, we observe a dramatic and unexpected change to multi-generation cycles in both the adult host and parasitoid. Intuitively, we would expect that resource competition in the larval stages would be more severe under such conditions, leading to lower survival rates, longer development times and reduced fecundity, but models that take into account these effects are found to be inadequate. We find that a model that also incorporates spatial heterogeneity in resource patch exploitation is necessary to describe the dynamics. We will present the data and discuss the modelling developments.
Key words: consumers, cycles, predator, prey