Olfactory perception of pheromones and host volatiles by the southern pine beetle, Dendroctonus frontalis Zimmerman (Coleoptera: Solytidae)

Abstract

The olfactory perception of pheromones and host terpenes by Dendroctonus frontalis was investigated by morphological and electrophysiological techniques. The morphology of the sensilla on the antennal club was studied by light, transmission electron and scanning electron microscopy. Four sensillum types were observed. The function of 3 of the 4 types was indicated from preliminary electrophysiologixal studies. The sensilla basiconica and sensilla trichodea II were found to be olfactory receptors. Cells associated with both types responded to stimulation by bark beetle pheromones and host terpenes. The sensilla trichodea III were longer than the other sensilla and were found to be mechanoreceptors. Fluted sensilla were described for the first time in Scolytidae. Morphological evidence was presented for electrical coupling for both dendrites associated with sensilla basiconica and axons. The antennal olfactory acceptor (receptor site) population was described by electroantennogram (EAG) and single unit recordings in conjunction with a technique involving differential adaptation.