The carrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), is an insect pest in carrot production in Ontario. The aim of this study was to survey the egg parasitoids attacking the carrot weevil in carrot fields in Ontario, and elucidate the seasonal and chemical ecology of these natural enemies. / Field surveys were conducted during three years in commercial carrot fields in the Holland Marsh and district marshes to detect the presence of carrot weevil egg parasitoids, to determine their geographical distribution and to evaluate the effect of insecticides on the rate of emergence and the activity of parasitoid adults. Two egg parasitoids, Anaphes listronoti Huber and A. victus Huber were found. The dominant species Anaphes listronoti is gregarious, was recovered from most of the sampled fields and was distributed in all sampled marshes whereas the solitary parasitoid A. victus was only sporadically found in the Holland Marsh. These Anaphes species occurred in carrot fields from the end of April to the beginning of September and seasonal parasitism averaged 33% in commercial carrot fields and up to 79% in an untreated plot. The insecticides phosmet, diazinon and cypermethrin used in carrot production, did not affect emergence rate of parasitoid adults indicating that immature stages are protected against insecticide penetration in the host egg. However, insecticide applications decreased parasitism rates and suggest a lethal effect on parasitoid adults by direct contact and insecticide residues, although no difference was observed between treatments. / Laboratory studies were performed to determine the existence of a sexual pheromone produced by female A. listronoti using a four-arm olfactometer. An automated system of insect tracking was developed to quantify male behavior in the olfactometer. The response of males to odor emitted by virgin females less than two days of age was measured. Virgin females less than one-day-old released a long-range pheromone from 4 hours until 16 hours after the onset of the photophase. Females of one and two days of age started to emit the sexual pheromone earlier than younger females.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34935 |
| Date | January 1998 |
| Creators | Cormier, Daniel. |
| 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: 001641781, proquestno: NQ44392, Theses scanned by UMI/ProQuest. |
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