The role of lanierone in the chemical ecology of Ips pini (Coleoptera: Scolytidae) in California

Five doses of lanierone (2-hydroxy-4,4,6-trimethyl-2,5-cyclohexadien-1-one) were tested with one dose of enantiomerically pure [99.4% (4R)-(-)] ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol) for activity as an aggregation pheromone of Ips pini (Say) in California. The response of I. pini to 1 mg/day ipsdienol + 20 micrograms/day lanierone was significantly greater than the response to ipsdienol alone, but the response pattern did not demonstrate a clear dose-response relationship. The response to the highest dose of lanierone (2 mg/day) was significantly lower than the response to ipsdienol alone. Ipsdienol attracted significantly more I. pini than a male-infested log. Lanierone did not alter the percentage of male I. pini responding to ipsdienol alone. Neither sex of I. pini or Dendroctonus brevicomis LeConte from California produced detectable amounts of lanierone, but myrcene-aerated male D. brevicomis produced 97.8%-(4S)-(+)-ipsdienol. The black-bellied clerid, Enoclerus lecontei (Wolcott) (Coleoptera: Cleridae) was attracted to lanierone when released with ipsdienol. Neither compound was attractive when released alone, proving synergism for the kairomone of this predator. Lanierone did not influence the response of the predators Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae) and Enoclerus sphegeus (F.) (Coleoptera: Cleridae), which were attracted to all treatments containing ipsdienol. Tomicobia tibialis Ashmead (Hymenoptera: Pteromalidae) responded in significantly greater numbers to the male-infested log than it did to ipsdienol or ipsdienol + 20 micrograms/day lanierone