Carbon dioxide detection in adult Odonata

• Single-cell recordings from antennal sensory neurons of Ischnura elegans are shown.
• Olfactory sensory neurons strongly inhibited by CO2 were identified in this species.
• These neurons responding to CO2 are also excited by amines and inhibited by acids.
• Further investigations are needed to assign a biological role to these Odonata sensory neurons.

The present paper shows, by means of single-cell recordings, responses of antennal sensory neurons of the damselfly Ischnura elegans when stimulated by air streams at different CO2 concentrations. Unlike most insects, but similarly to termites, centipedes and ticks, Odonata possess sensory neurons strongly inhibited by CO2, with the magnitude of the off-response depending upon the CO2 concentration. The Odonata antennal sensory neurons responding to CO2 are also sensitive to airborne odors; in particular, the impulse frequency is increased by isoamylamine and decreased by heptanoic and pentanoic acid. Further behavioral investigations are necessary to assign a biological role to carbon dioxide detection in Odonata.

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