Waters from normal larvae of Aedes aegypti (L.) are highly attractive to ovipositing conspecific females, whereas waters from larvae infected with the entomopathogenic digenean parasite, Plagiorechis elegans Rudolphi, are rendered strongly repellent. The production of the repellent appears to be mediated by the degree of environmentally induced stress experienced by the larvae. Whereas waters from fully fed larvae were highly attractive as an oviposition site, these were rendered progressively less attractive, and eventually strongly repellent as the larvae were deprived of food over a period of 7 days. Crowding of the larvae elicited similar repellent effects as did close contact between larvae and the walls of the container in which they were reared. The site of infection in the tissues of the mosquito larvae also influenced the intensity of repellency. Thus, infections of the head and thorax induced the highest degree of repellency, and infections of the abdomen the lowest. The repellent effect overrode attraction and remained stable for more than one week at 27°C, and even longer at lower temperatures. Stressors which induced repellency all precipitated similar physical and physiological changes in mosquito larvae. They reduced wet and dry weights and the concentration of serum carbohydrates, amino acids, proteins and lipids. Both infection and crowding rendered larvae anorexic. As well, infected larvae appeared to be unable to convert trehalose to glucose, thereby exacerbating the energy deficit. Incubating infected larvae in a dilute glucose solution significantly reduced the repellent effect of their waters. Addition of glucose to already repellent waters had little effect. Larvae of another species, Aedes atropalpus Coquillett, were equally capable of producing repellent effects when infected with P. elegans, and gravid females of Ae. aegypti were equally sensitive to these as to conspecific waters. This sensitivity, however, was not reciprocal. Aedes
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35423 |
| Date | January 1997 |
| Creators | Zahiri, Nayerolsadat. |
| Contributors | Rau, M. E. (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 | Doctor of Philosophy (Department of Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001617071, proquestno: NQ44640, Theses scanned by UMI/ProQuest. |
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