Towards an Understanding of Scent Capture in Beetles with Lamellate Antennae: Implications for the Design of a Scent-Tracking Robot.

The capture of scent molecules is the first key step in olfaction. Capture is governed by the properties and dynamics of the fluid bearing the scent molecules, and by the architecture of the olfactory sensory surface immersed in that fluid. We are interested in understanding the capture process in keen-scented animals, with a view to applying the resultant knowledge to the design of scent-tracking robots. Subjects for our programme include four species of land-based beetle: Rhipicera femorata (Rhipiceridae), Callirhipis robusta (Callirhipidae), Polyphylla boryi and Melolontha melolontha (both Scaribaeidae). The males of these species possess relatively large, architecturally complex, lamellate antennae; all three features suggest a keen sense of smell. As the first step towards understanding scent-capture in these beetles, and prior to conducting fluid dynamics experiments, we have used X-ray micro-computed tomography to characterise their antennal morphometry (e.g. surface areas, interlamellar bond angles and distances). In the case of Rhipicera femorata, Callirhipis robusta, and Polyphylla boryi, we have also used scanning electron microscopy to characterise the number and type of sensilla present on their olfactory sensory surface. We will describe our findings, and the implications these findings might have for the design of scent-tracking robots.