Intraspecific attraction and host tree selection by adult Capnodis tenebrionis

Management of the peach flatheaded rootborer, Capnodis tenebrionis, a major pest of stone-fruit orchards in the Mediterranean area, is based on preventive measures, due to insufficient information on the pest population levels, and the ineffective methods aimed at monitoring the adults. This study aimed at elucidating the role of chemical communication between adults, and the involvement of the host tree as a meeting point for males and females. This information may assist in setting the base for a monitoring procedure for the beetle population and the development of baits to lure the beetle to a trap. We detected no sexual communication signals or kairomonal effects through bioassays of airborne beetles' or host plants' volatiles. We found that volatile cues, originating from either healthy or stressed nitrogen-rich host trees, attract the adults into a confined area. Thus, we conclude that beetles are attracted to nitrogen-rich trees. It is suggested that visual cues may be used to locate conspecifics on a chosen tree, and tactile stimuli may then be applied to distinguish females from males. A female seeking a suitable tree for oviposition may follow volatile cues originating from a stressed nitrogen-rich tree accompanied by other stress characteristics volatiles.