Plasticity in response to semiochemicals as part of a reproductive diapause syndrome in a long-lived moth, Caloptilia fraxinella (Lepidoptera: Gracillariidae)

• Author / Creator

  Lemmen, Joelle K.

• In Lepidoptera that exhibit a delay in mating, response to semiochemicals associated with mating may be plastic, to optimize timing of reproductive events with appropriate environmental conditions. This thesis examines male response to female sex pheromone and male and female response to host plant volatiles in a long-lived adult moth, Caloptilia fraxinella (Lepidoptera: Gracillariidae). Adult C. fraxinella undergo a nine month period of reproductive inactivity from eclosion in July until the following spring when adults emerge from overwintering locations in a reproductively active state. Male response to female sex pheromone is highest when moths are reproductively active. In Chapters 2 and 3, I investigate exogenous and endogenous mechanisms that impact male pheromone response plasticity. When males are in reproductive diapause, long day/warm conditions terminate, while short day and cool conditions or a natural declining photoperiod maintain diapause. The juvenile hormone analogues (JHA) methoprene and pyriproxyfen similarly enhance male antennal and behavioural response to pheromone in the fall. In the most recent experiments, JHA treatment impacts pheromone response earlier in the summer, indicating a possible physiological change in the tested population of moths. Chapter 4 tests whether males and females exhibit plasticity in response to host plant volatiles that depends on physiological state. Male behavioural response to pheromone is not enhanced by the presence of an ash seedling. Male and female antennal response to individual ash tree volatiles is plastic, and response to the volatiles is highest when moths are reproductively active. JHA treatment enhances male and female antennal responses to host volatiles during reproductive diapause, and impacts males and females differently. Chapter 5 confirms that males are in a state of reproductive diapause in the summer and fall with shorter sex accessory glands compared to reproductively active males in the spring. JHA treatment enhances the protein content of male sex accessory glands in the fall. The main proteins present in male sex accessory glands are identified. The plasticity of response to semiochemicals documented here in C. fraxinella depends on physiological state, and is mediated by environmental conditions and JH in males, and JH and nutrition in females.

• Subjects / Keywords

  • Lepidoptera
  • Juvenile hormone
  • Electroantennogram
  • Caloptilia fraxinella
  • Wind Tunnel
  • Pheromone response plasticity

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R37Q3D

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.