Inducible anti-herbivore defences of the annual sunflower (Helianthus Annuus) against a specialist sunflower beetle (Zygogramma Exclamationis)
Lethbridge, Alta. : University of Lethbridge, Dept. of Arts & Sciences.
This thesis aims to determine the effects of sunflower plant defences on the specialist sunflower beetle and whether sunflower beetles modify their behaviour in response to plant defences as a form of herbivore offence. Chapter 1 begins with a general introduction, reviewing previous literature on inducible plant defences and herbivore offence. Chapter 2 investigates plant defence induction in sunflowers, initiated by sunflower beetle larvae feeding and mechanical damage. No evidence of plant defence induction was found. Chapter 3 investigates the possibility of herbivore offence in sunflower beetles, specifically: selective oviposition on undamaged sunflowers, avoidance of damaged leaves and plants, and gregarious feeding. No evidence of selective oviposition, or avoidance of damaged leaves or plants was found. Evidence of gregarious feeding was found as larval survivorship increased with increasing larval densities. Chapter 4 summarizes the results of Chapters 2 and 3, and proposes future lines of research based on these findings.
herbivore offence , plant defences , selective oviposition , sunflower , sunflower beetle