Phenotypic plasticity in insect chemical communication: an ecophysiological approach

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The goal of this research is to understand factors that drive plasticity in various types of insect chemical communication (mate location, host location). Our study systems are moths (Lepidoptera) in which males compete for females by scramble competition and there is intense selection on the male receiver to be the first to locate a calling female. Intraspecific sex pheromone communication in the Lepidoptera likely evolved from a preadaptation of sensory and orientation mechanisms for locating plant hosts and our research includes investigation into plasticity in response to plant-based chemical cues in addition to conspecific pheromone signals. Plasticity in chemical communication in insects can result from gradual or sudden changes in physiological state. We will assess how variation in physiological state due to insect age/hormone levels, satiation level, and pathogen load influence plasticity in production and response to intra- and interspecific chemical cues. The effect of more immediate changes in physiological state that occur after mating and in response to previous exposure to chemical cues will be assessed in moths with different reproductive strategies. As state-dependent plasticity in chemical communication will interact with environmental conditions to affect odour-mediated flight behaviour, our assessments will include behavioural analyses in the lab and under natural field conditions. Moth study systems will have a range of reproductive strategies (income vs. capital breeders) and adult life history traits (short vs. long-lived; feeders vs. non-feeders) to maximise the ecological traits that should promote plasticity in chemical communication. The importance of phenotypic plasticity in chemical communication of insects remains poorly understood. We will unravel the impact of physiological state of signalers and responders on variation of chemical communication and odour-mediated behaviour under various ecological conditions. Integration of physiological and ecological components that promote plasticity in a neuroecological context will advance our understanding of insect use of environmental information that dictates behaviour and moulds interactions at various levels of biological organization. Further, the moth study systems used in this work are of ecological (native defoliators of the boreal forest) and economic (invasive species) importance so that understanding plasticity of chemical communication will contribute to the development of alternative control strategies that exploit these naturally plastic chemically-mediated behaviours.