Screening spruce for white pine weevil resistance

• Project description
• Distribution of P. strobi in North America
• Genetic variation in canadian weevil populations
• Range of Sitka spruce
• Sources tested for resistance in Western North America
• White pine weevil resistance screening trials
• Mass screening for resistance (Jordan River plantation)
• Ghost trial: studies using caged insects clarified the mating system of weevils
• Artificial wounding studies: Studying plant defenses
• Insect - plant relationships
• Are weevil resistant trees also resistant to other insects?
• Conclusions
• Selected references

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Artificial wounding studies: Studying plant defenses

David Brescia, Elizabeth Tomlin, Kornelia Lewis and René Alfaro (not in picture) used artificial wounding to study the production of traumatic resin by spruce trees. Traumatic resin production is a defense system in many conifers against insect and disease invasion.

Artificial wounding

Artificial wounding induced the cambium to produce a ring of traumatic resin canals (TRC) which are visible in the xylem tissue. This technique has since been used at the University of  British Columbia to screen northern spruce genotypes for resistance to weevil. Ms. Lesley Manning, of the Pacific Forestry Centre, supervised the microscopy for this aspect of this project.

Elizabeth Tomlin, John Borden and colleagues at Simon Fraser University studied the chemistry of traumatic resin produced by the tree in response to weevil wounding. Traumatic resin is richer in monoterpenes than regular resin canal resin. It is therefore more fluid and more likely to inundate the weevil larval galleries. Picture shows Cheryl Horvath (UVic coop student) working with John Borden of Simon Fraser.

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