OLFACTORY AND ACOUSTIC BEHAVIOR OF PSEUDOHYLESINUS-NEBULOSUS (COLEOPTERA, SCOLYTIDAE) ON DOUGLAS-FIR BARK

Mature male Pseudohylesinus nebulosus (LeConte) walking on Douglas-fir logs were strongly arrested and stridulated at a female gallery or artificial galleries with female frass, but not at artificial galleries without frass. This response diminished after the female accepted a male in the gallery. Mature males emitted distinctive chirps for stress, attraction and rivalry, all of which differed from chirps of immature males, and pushed intruding males from the gallery. Reproductively immature adult males were weakly arrested both at artificial galleries and those of feeding, and were not aggressive toward other males. Only stress chirps of immature males were distinguishable from chirps in other contexts. Adult reproductive maturation probably includes development of close-range olfactory and acoustic signals and territorial behavior.