Functional anatomy of sensory structures on the antennae of Psylliodes chrysocephala L. (Coleoptera : Chrysomelidae)

The ultrastructure and distribution of sensilla on the antennae of the cabb age stem flea beetle, Psylliodes chrysocephala, were investigated using sca nning and transmission electron microscopy techniques. Eight different sens illar types were distinguished. These were; hair plate sensilla, sensilla c haetica, three types of sensilla trichodea, sensilla basiconica, grooved pe g sensilla and styloconic sensilla. The sensilla chaetica are known to be g ustatory receptors. Ultrastructure indicates that the hair plate sensilla a nd sensilla trichodea type one are probably mechanoreceptors, whilst the se nsilla styloconica are probably thermo-hygro receptors. These thermo-hygror eceptors are unusual in that they are innervated by two sensory cells (one hygroreceptor and one thermoreceptor) rather than the more usual triad. The remaining four sensillar types all have a porous hair shaft, indicating an olfactory role. One of these (the grooved peg sensillum) may also have a t hermoreceptive function. No sexual dimorphism was found in the structure, n umber or distribution of the antennal sensilla. (C) 2000 Elsevier Science L td. All rights reserved.