Ultramorphology Of Proboscis Sensilla In Noctuinae And Plusiinae(Lepidoptera: Noctuidae)

The proboscis of higher Lepidoptera is a complex fluidic system consisting of twoextremely elongated galeae and functions like a drinking straw. Each galea bears varioustypes of sensilla, which play important roles in feeding activities in the Lepidoptera.Noctuidae is the largest family with many agricultural pests of great economicsignificance. Species of the family Noctuidae vary in feeding habits, such as fruit-piercing,nectar-feeding, blood-sucking, tear-feeding, and sweat-feeding. However, the morphologyof the proboscis sensilla of Noctuidae is not satisfactorily explored hitherto.Here we examined and compared the morphology of proboscis sensilla of five speciesin five genera belonging to Noctuinae and24species in17genera belonging to Plusiinae,using scanning electron microscopy.In Noctuinae and Plusiinae, the outer surface of the proboscis is fluted with cuticularprocesses and a great number of sensilla. Three types of sensilla (sensilla chaetica, sensillabasiconica, and sensilla styloconica) are found on the proboscis in Noctuinae, and the wholeproboscis is fluted with cuticular processes. While in Plusiinae, sensilla chaetica, sensillabasiconica, sensilla styloconica, and sensilla coeloconica are found and only the proximalregion of the proboscis is fluted with the cuticular processes.The differences of proboscis sensilla between Noctuinae and Plusiinae mainly reflectedin the number and shape of sensilla styloconica, number and distribution of sensilla chaetica,and the types of sensilla that occur on the tip region of the proboscis. The tip region ofproboscis in Noctuidae bears more than80sensilla styloconica with six or seven longitudinalribs; while in Plusiinae just bears about10sensila styloconica without longitudinal ribs butsmoothly. Sensilla chaetica occur on the whole external surface of the proboscis and becomeshorter and more scattered toward the tip in Noctuinae, but occur on the proximal region ofthe proboscis and with a less number in Plusiinae. In Noctuinae, the tip region of theproboscis bears sensilla chaetica, sensilla basiconica, and sensilla styloconica, while inPlusiinae, the tip region bears sensilla basiconica, sensilla styloconica, and sensillacoeloconica, and without sensilla chaetica. The variation of sensilla types, the variation of shape and number of sensilla styloconica,and the variation of the distribution of sensilla chaetica could be used as characters fortaxonomy of subfamily in Noctuidae.The Plusiinae may be a monophyly supported by the same types of sensilla, especiallythe closely resembled sensilla styloconica and specific sensilla coeloconica, similardistributions on their proboscis. Based on the present study, we predict that the adults ofNoctuinae and Plusiinae are flower-visiting species.