The Antennal Receptors and Olfactory Response of Ips confusus (Coleoptera: Scolytidae) to Male Sex Attractant in the Laboratory1

Abstract

There are at least 5 different types of sensilla on the antennae of Ips confusus (LeConte). Short, thin-walled pegs (sensilla basiconica) and long, thin-walled hairs (sensilla trichodea) are permeable to crystal violet dye and are likely to be olfactory receptors. Long, thick-walled hairs (sensilla chaetica) are probable tactile receptors. Two unusual hairs were noted, a unilaterally pectinate and a long, bilaterally pectinate type. The function of the latter hair may be in the areas of touch, wind pressure, or sound reception. In both sexes, removal of the antennal clubs eliminates a positive response to male sex attractant. Responses of females after removal or covering various portions of the club indicate that the sensilla trichodea are receptors of the sex pheromone. Orientation behavior after unilateral antennectomy confirms the theory that the orientation of I. confusus to the sex attractant is a chemoklinotaxis.