EFFECTS OF ENANTIOMERIC BLEND OF VERBENONE ON RESPONSE OF IPS PARACONFUSUS TO NATURALLY PRODUCED AGGREGATION PHEROMONE IN THE LABORATORY

The aggregation pheromone produced by male Ips paraconfusus (Coleopter a: Scolytidae) tunneling in Monterey pine, Pinus radiata, logs was tra pped on Porapak Q. A concentration of an extract of trapped volatiles that attracted beetles was determined in the laboratory through a conc entration-response analysis of walking behavior of males and females. The interruptant effects of four concentrations of verbenone on respon se to a constant concentration of this naturally produced aggregation pheromone were tested with males and females. Independent of its enant iomeric composition [99.5% (S)-(-), 93.1% (S)-(-), and 98.3% (R)-(+)], verbenone significantly reduced the percentage of females (but not ma les) reaching the attractant source. However, when the time required f or beetles of both sexes taken together to reach the attractant source was considered, verbenone of higher enantiomeric purity had a greater effect on beetle behavior. Solutions of 99.5% (S)-(-)- and 98.3% (R)- (+)-verbenone increased the time required for beetles to reach the att ractive source when compared to 93.1% (S)-(-)-verbenone. When pooled a cross enantiomeric blends, increasing concentrations of verbenone resu lted in slower responses in beetles that reached the attractant source within 2 min. Males and females did not respond to verbenone alone.