Taste recognition through tarsal gustatory sensilla potentially important for host selection in leaf beetles...

It is well known that Diptera and Lepidoptera can recognize tastes through their legs, which allows them to select suitable hosts. In Coleoptera, the largest insect order, however, the role of the legs in taste recognition to aid in host selection is unclear. In the present study, we investigated taste recognition through the legs of Chrysomelidae, Coleoptera. Through morphological observations, we found that all subfamilies of Chrysomelidae exhibit gustatory sensilla in the distal leg segment, i.e., the tarsus. In contrast, we did not find evidence of these sensilla in the species that we examined from four families of Coleoptera. We confirmed that different tastes, i.e., sweet, bitter, and leaf surface wax, were received through the tarsal sensilla of Chrysomelidae by recording the electrophysiological responses of the sensilla. Further, we found that Galerucella grisescens (Chrysomelidae) can respond to different tastes used in the electrophysiological tests using only their tarsi, whereas Henosepilachna vigintioctomaculata (Coccinellidae), lacking tarsal gustatory sensilla, did not exhibit similar responses. Our results suggest that although tarsal taste recognition is not common throughout Coleopteran species, it may be a common feature in Chrysomelidae, and tarsal gustation may play an important role in host selection in this family.