Strains of Bacillus thuringiensis active against Coleoptera were evaluated for toxicity against the adult stage of the carrot weevil, Listronotus oregonensis. Mortality and frass bioassays using a suitable semi-artificial diet showed strains A30, A429 and BTT to be highly toxic. Mortality persisted after initial exposure to the bacteria with the survivors not resuming normal feeding. Attempts to reisolate B. thuringiensis from the insects revealed B. thuringiensis-like organisms in the gut and in/on other structures. At the midgut pH of the insect (pH 8.0), the crystals of the toxic strains were significantly more soluble in vitro than were crystals of the less toxic strain A311. Proteolytic activation of the crystals with gut extracts yielded a protein band (66-67 kDa) for strains A30 and A429 which was similar to he apparent molecular weight of the toxin protein for BTT. Evidence suggests that the low toxicity of strain A311 might be due, in part, to the absence of the toxic moiety of the $ delta$-endotoxin.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.67541 |
| Date | January 1993 |
| Creators | Saade, Fabienne Eugenie Joseph |
| Contributors | Yule, W. N. (advisor), Dunphy, G. 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 | Master of Science (Department of Entomology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001338407, proquestno: AAIMM87805, Theses scanned by UMI/ProQuest. |
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