Electrophysiological and Morphological Characterization of Contact Chemosensilla in Adults and Larvae of the Butterfly, Atrophaneura alcinous

Distribution and electrophysiological responses of contact chemosensilla were examined in the Aristolochiaceae-feeding butterfly Atrophaneura alcinous. In adult butterflies, tarsal contact chemosensilla of the foreleg were classified into two groups based on length: long- and short-type sensilla. Long-type sensilla were distributed much more widely in females than in males, whereas short-type sensilla were found at the edge of the tarsi in a similar manner in both sexes. Taste responses of the long- and short-type sensilla to methanol extracts of Aristolochia debilis and Citrus spp. were recorded. Aristolochia debilis extracts evoked spikes with different amplitudes, whereas Citrus spp. extracts evoked spikes with a single amplitude in the long-type sensilla. Short-type sensilla did not respond to either extract. Moreover, we recorded responses to different concentrations of sucrose and NaCl. Results suggest that adult butterflies can discriminate the taste of host plant components from other chemicals using long-type sensilla during oviposition and may recognize diets containing sugar and salts during feeding using short-type sensilla. In the larval mouthparts, there were lateral and medial styloconic sensilla on the maxillary galea and epipharyngeal sensillum on the epipharynx. Electrophysiological responses of these sensilla suggest that larvae can discriminate between host plant compounds.

Automated summary

This study found that the tarsal contact chemosensilla in adult butterflies are classified into long- and short-type sensilla, which show different taste responses to extracts from different plants. The results suggest that adult butterflies can discriminate the taste of host plant components using long-type sensilla during oviposition and may recognize diets containing sugar and salts using short-type sensilla during feeding.