Speaker
Description
Chemical senses are crucial for species adaptation, particularly in insects, as they facilitate interactions between animals and their environment. While most insects are terrestrial, some have transitioned back to aquatic environments. This shift has likely demanded substantial adaptations to their chemosensory systems in order to cope with distinct physico-chemical constraints. How the fundamentally aerial chemosensory equipment of insects was remodelled in lineages of aquatic insects is a major and unexplored topic of interest in evolutionary ecology. We examine this question in the coleopteran suborder Adephaga, which includes beetle species that exhibit a wide range of affinities to freshwater, from fully terrestrial to highly specialised aquatic species.
Our research focuses on the diving beetle Rhantus suturalis, a common species in Western European ponds and a significant predator of mosquito larvae. The interactions of diving beetles with other freshwater organisms have long attracted the attention of ecologists, but the underlying mechanisms, such as the nature of the olfactory signals involved, remain elusive. Using physicochemical analyses (GC-MS), we identified chemicals from ecologically relevant sources, and we confirmed their detection by R. suturalis antennae through electro-antennogram recordings. This provides the first insights into the olfactory capacities of these insects.
Additionally, transcriptomics revealed numerous odorant receptor genes expressed in the sensory organs of R. suturalis. Ongoing work aims to characterise the function of these receptors using heterologous expression in Xenopus oocytes and two-electrode voltage clamp. This will offer insights into the evolution of receptors that are tuned to specific compounds in aquatic environments.
