Scanning Electron Microscope Study of Antennae and Mouthparts in the Pollen-Beetle Meligethes (Odonthogethes) chinensis (Coleoptera: Nitidulidae: Meligethinae)

Simple Summary The present paper is aimed to further explore the structure of the antennae and mouthparts of specialized beetle species living on flowers, as well as the functions of their associated sensilla. In this study, we used scanning electron microscopy (SEM) to observe and describe for the first time the fine morphology of sensilla on the antennae and mouthparts of the pollen-beetle Meligethes (Odonthogethes) chinensis, a common Chinese species associated with flowers of Rosaceae. The results show that there are six types and twelve subtypes of sensilla on male antennae; seven types and fourteen subtypes on female antennae; seven types and seventeen subtypes on male mouthparts; seven types and sixteen subtypes on female mouthparts. The sensilla on the antennae and mouthparts of Meligethinae that feed on pollen were finally compared with similar sensilla known to occur in other insects, in order to obtain more insights on the evolution of these sensorial structures in specialized flower-inhabiting insects. Meligethes (Odonthogethes) chinensis is a common Chinese phytophagous species in the family Nitidulidae. Its main larval host plant is Rubus idaeus L. (Rosaceae), and adults feed on pollen and other floral parts. In this study, we used scanning electron microscopy (SEM) to observe and study the fine morphology of sensilla on the antennae and mouthparts of M. chinensis. The results show that there are six types and twelve subtypes of sensilla on male antennae; seven types and fourteen subtypes on female antennae; seven types and seventeen subtypes on male mouthparts; seven types and sixteen subtypes on female mouthparts. Sensilla coeloconica (SCo) are found on the female antennae of M. chinensis only, and they are also reported on the antennae of Nitidulidae for the first time. SCo2 on the labrum present sexual dimorphism, and one subtype of sensilla basiconica (SB6) is presented on the tip of maxillary and labial palps of the male only, while other types of sensilla are very similar on the mouthparts of male and female. Finally, by comparing similar sensilla in other insects, we also attempted to discuss the functions of all sensilla on the antennae and mouthparts of M. chinensis.

Automated summary

This study utilized SEM to observe and study the fine morphology of sensilla on the antennae and mouthparts of the pollen-beetle Meligethes (Odonthogethes) chinensis, revealing multiple types and subtypes of sensilla. By comparing similar sensilla in other insects, the research aimed to discuss the evolution and functions of these sensorial structures in specialized flower-inhabiting insects.