The effects of intraspecific and interspecific competition, host plant, and prior host plant experience on fecundity, rate of oviposition and mortality of adults and larval survival of Delia radicum Bouche (Cabbage Maggot (CM)), D. antiqua Meigen (Onion Maggot (OM)), and D. platura Meigen (Seed Corn Maggot (SCM)), were studied on cabbage, onion and bean plants. / An optimum density for maximum fecundity per female was observed when the four experimental densities were compared. This optimum density was higher on host than on non-host plants. CM females were host specific and did not oviposit on non-host plants. Rates of oviposition and mortality over a 30-day period were calculated for each density. The rate of oviposition was slower at higher densities on host plants for CM, OM and SCM. The rate of mortality increased at the highest density for CM (cabbage), OM (bean) and SCM (cabbage), but remained unaffected for OM on onion and cabbage and for SCM on onion and bean, when densities were compared. For OM, a delay in the rate of oviposition and mortality on cabbage (non-host plant) when compared with onion (host plant), suggests that cabbage was not as readily accepted as an oviposition site. Interspecific competition experiments at six density ratio's of SCM:OM indicated increased fecundity, or an increase in the rate of oviposition for OM, at the lower densities when single and mixed species were compared. For SCM no effects on fecundity were recorded, but the rate of oviposition was slower and rate of mortality faster at the lowest density in the presence of OM. Similar studies with SCM and CM showed no such effects of competition. / Host plant exposure of SCM females during the pre-oviposition period resulted in a delay in initial acceptance of subsequent host plants as oviposition sites. This happened only when females were exposed to a secondary host during the pre-oviposition period. Once oviposition began, host discrimination ceased and a switch in oviposition sites to the preferred host did not alter the rate of oviposition. In CM, the rate of larval development increased at density 6 (optimum density). Above this density a decrease in the rate of development and a significant reduction in pupal weight was observed. Time required for fly emergence was not affected by increasing larval densities.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41017 |
| Date | January 1992 |
| Creators | Noronha, Christine M. (Christine Mary) |
| Contributors | Hill, S. B. (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 Entomology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001324177, proquestno: NN87854, Theses scanned by UMI/ProQuest. |
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