Sense organs on the antennal flagellum and certain mouthparts of three cerambycids (Insecta, Coleoptera)

The sense organs on the antennae, mandilbes, labrum, labial palps and maxillary palps of Neoclytus muricatulus muricatulus (Kby.), Acmaeops proteus (Kby.) and Xylotrechus undulatus (Say) were studied with light, scanning electron and transmission electron microscopes to determine the types, distribution and innervation of the various types of sensilla. There are three types of sensilla on the mandibles and labrum; sensilla chaetica, sensilla trichodea, and sensilla campaniformia. The labial and maxillary palps have sensilla chaetica and sensilla trichodea along the sides of the palp subsegments and near the intersegmental membrane between each subsegment. A sensory plate, containing several hundred sensilla basiconica, is situated on the tip of each palp. Dome-shaped organs are located around the periphery of the sensory plate. The antennae possess the greatest variety and number of sensilla. Thirteen types of sensilla are distributed over the surface of the antennae. Both, the sensilla trichodea and sensilla basiconica are chemoreceptors and the sensilla chaetica are mechanoreceptors. Dome-shaped sense organs, that are probably sensilla campaniformia, were found. The sensilla chaetica are thick-walled and innervated by one sensory neuron. Sensilla trichodea have a terminal pore with the dendrites of the sensory neurons situated just below the pore. The sensilla basiconica are thin-walled pegs with many pores perforating the surface of the peg. The dendrites in the lumen of the basiconic peg branch out to all of the pores. Each type of sensillum is innervated by a specific number of neurons. Trichogen and tormogen cells are associated with each sensillum.