Showing papers by "Cheryl J. Briggs published in 2001"
TL;DR: Using mechanistic models, it is determined that spatial population structure did not contribute to persistence, and spatially explicit models are not needed, and habitat structure reduced the success of predators at locating prey outbreaks, allowing between-plant asynchrony of local population cycles due to random colonization events.
Abstract: Understanding spatial population dynamics is fundamental for many questions in ecology and conservation1,2,3,4. Many theoretical mechanisms have been proposed whereby spatial structure can promote population persistence, in particular for exploiter–victim systems (host–parasite/pathogen, predator–prey) whose interactions are inherently oscillatory and therefore prone to extinction of local populations5,6,7,8,9,10,11. Experiments have confirmed that spatial structure can extend persistence11,12,13,14,15,16, but it has rarely been possible to identify the specific mechanisms involved. Here we use a model-based approach to identify the effects of spatial population processes in experimental systems of bean plants (Phaseolus lunatus), herbivorous mites (Tetranychus urticae) and predatory mites (Phytoseiulus persimilis). On isolated plants, and in a spatially undivided experimental system of 90 plants, prey and predator populations collapsed; however, introducing habitat structure allowed long-term persistence. Using mechanistic models, we determine that spatial population structure did not contribute to persistence, and spatially explicit models are not needed. Rather, habitat structure reduced the success of predators at locating prey outbreaks, allowing between-plant asynchrony of local population cycles due to random colonization events.
196 citations
TL;DR: A series of stage-structured models that investigate the effects of autoparasitism on population dynamics are presented and the effects are compared with those of other forms of interference competition.
29 citations
TL;DR: The gall‐forming midge Rhopalomyia californica was exposed experimentally to parasitism and predation during only the egg stage, During only the larval stage, during neither stage, or during both stages.
Abstract: Summary
1. The gall-forming midge Rhopalomyia californica was exposed experimentally to parasitism and predation during only the egg stage, during only the larval stage, during neither stage, or during both stages.
2. The combined action of natural enemies that attack during both the egg stage and the larval stage led to the lowest number of midges and total insects (midges + parasitoids) in the next generation, and the highest percentage parasitism.
3. The larval parasitoid killed a large fraction of hosts without producing new parasitoid offspring, while there is some indication that the egg parasitoid on its own tended to produce the most parasitoid offspring. The contrasting implications of host mortality versus parasitoid production for biological control are discussed.
4. Exposure to larval parasitoids resulted in a reduction in the number of egg parasitoid offspring produced, but exposure to the egg parasitoid did not affect the number of larval parasitoid offspring produced significantly.
16 citations