Antennal Sensory Structures of Conotrachelus nenuphar (Coleoptera: Curculionidae)

Abstract

Antennae of both sexes of Conotrachelus nenuphar (Herbst) were studied by scanning and transmission electron microscopy to determine types and locations of sensory structures present. Six types of hairlike structures (I–VI) were found. Type I are multiporous grooved sensilla that contain dendrite branches in the lumen and occur in a single row on the antennae. Type II are multiporous wall-pore hairs that are innervated by two neurons that branch distally. They occur predominantly in two sensory bands around the club. Type III are ridged externally, have thick walls with no pores, no dendrites in the lumen, and were the most numerous. Type III hairs were found on all antennal segments. Type IV are multiporous wall-pore sensilla, contain two dendrites, and are found predominantly on the tip of the club. Type V are long, ridged, thick-walled sensilla that project at nearly right angles from the cuticle. They contain four dendrites, a terminal pore, and are found only on the club. Type VI are long stout hairs with truncated tips, no dendrites in the lumen, and are found on the scape, pedicel, and flagellar segments 1 through 6. No wall pores were seen in cross sections. Short pegs and campaniform sensilla were also found.