Faculty of Science, Engineering and Built Environment
School of Life and Environmental Sciences
Environmental effects on chemical communication in an invasive bark beetle, Ips grandicollis.
Participants: Dr Matthew Symonds (PI) and Prof John A Endler
Aims and background: Like all animals, insects rely on signals to attract mates, locate food, deter enemies and interact with other individuals. These signals are intimately associated with the environment in which they are transmitted. If the environment changes, the nature of the signal and response can be altered. For example, properties of bird song are affected by the noise of traffic in urban environments, and the efficacy of fish visual signals is reduced in aquatic environments as a result of algal blooms. In insects, the predominant communication modality is chemical (pheromones), but there is relatively little known about the extent to which local environment influences the production of and response to these chemical signals. Increased temperature or humidity may, for example, improve or impede the transmission of volatile chemicals. The aim of this project is to identify the relationships between particular aspects of the ambient environment (temperature, humidity, wind speed) and production and response to pheromone in a model insect species, the bark beetle Ips grandicollis, which is an invasive pest in Australian pine plantations. This species utilises an aggregation pheromone when colonising pine material en masse. Field and laboratory experiments will seek to establish how fluctuations in environmental conditions influence the rate at which they produce their aggregation pheromone, and their ability to respond. Further experiments will establish whether beetles reared under different environmental conditions differ in their chemical communication behaviour. The project will also involve a meta-analysis of published literature on pheromone-trapping programmes, to establish a more general picture of the ways in which ambient conditions influence insect chemical communication.
Scientific significance and innovation: Environmental effects are often implicated as drivers of physical, behavioural and evolutionary changes in signalling systems. In the case of chemical communication, however, the way in which ambient conditions can change patterns of pheromone production and response is still sketchily understood and poorly catalogued. The significance of these effects cannot be overstated, because chemical signals are vital to insects in order to bring together mates, and locate food and other resources. Furthermore, understanding the way in which environmental factors affect these communication systems may enable us to predict how species and ecological communities will respond to future environmental change. Globally, bark beetle species are severe pests and are predicted to become increasingly problematic to the silvicultural industry as a result of climate change. In Australia, Ips grandicollis appears to thrive in the hot and dry conditions that are expected to become prevalent in the south of the continent. Chemical communication is a vital part of their aggregation behaviour, and essential to their reproductive success. Consequently, knowledge of how environmental change may affect this process is an important factor in predicting future patterns of distribution and abundance for the species. The meta-analysis will provide a much-needed synthesis of information of the effect of climate on insect chemical signals, which up to now has largely been confined to descriptive case studies.
Potential national benefit and strategic alignment with the aims of the CIE: The primary beneficial outcome of the project is that it will provide a detailed picture of the effects of environmental conditions, and environmental change, on the way that an Australian invasive pest species,Ips grandicollis, uses chemical communication in order to colonise host trees and attract mates. The research therefore explicitly ties in to two Australian Government National Research Priority Goals, namely "Safeguarding Australia: Protecting Australia from Pest and Diseases" and "Environmentally Sustainable Australia: Responding to Climate Change and Variability". The project aligns strongly with the broad aims of the CIE by relating research on the direct impact of environmental variability on the sensory ecology of individual bark beetles in the short term, with the likely long-term population consequences. On an evolutionary timescale, the project will contribute to our knowledge of the extent to which insect chemical communication systems are shaped by their environment.
