Cercariae of the digenean Plagiorchis elegans cause high levels of morbidity and mortality among larvae of Aedes aegypti . The impact of this parasite on the larval population dynamics of the experimental host as mediated through intraspecific competition, egg hatchability and ovipositional preference was assessed by calculating the probability of pre-imagos to develop from one stage to the next, or to die within consecutive 24 h intervals. Attractiveness of the water to ovipositing females in a dynamic larval population was not affected by exposure to the parasite, but varied significantly over time, regardless of food abundance. In optimally fed populations, these changes were positively correlated with pupal production, but were not affected by early instar development. Most of the entomopathogenic effects of the parasite were expressed in the pupal stage. Thus, exposure to the parasite significantly reduced adult emergence, but did not greatly impair pre-imago development. Nonetheless, exposure to various levels of the parasite significantly increased mortality of all larval stages. Suboptimally fed larval populations displayed severely impaired development and produced few adults. Exposure to P. elegans increased adult production slightly, suggesting depensatory mortality. In nutritionally stressed populations, no correlation was found between biomass and ovipositional preference, but attractiveness of the water was significantly increased by the removal of individuals by pupation or mortality. Egg hatchability was not significantly affected by population structure, but varied with the nutrient content of the water. This study provides new insight into the use of parasites as agents in the biological control of mosquitoes.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.31534 |
| Date | January 2000 |
| Creators | Schwab, Anne Elisabeth. |
| Contributors | Rau, M. E. (advisor), Lewis, D. J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001810431, proquestno: MQ70497, Theses scanned by UMI/ProQuest. |
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