GREEN LEAF VOLATILES INTERRUPT AGGREGATION PHEROMONE RESPONSE IN BARK BEETLES INFESTING SOUTHERN PINES

Green leaf volatiles were shown to interrupt responses to aggregation pheromones of three species of bark beetles (Coleoptera : Scolytidae) which infest pines in the southern United States [the southern pine beetle, Dendroctonus frontalis Zimm.; the four-spined engraver, Ips avulsus (Eichhoff); and the five-spined engraver, Ips grandicollis (Eichhoff)]. The order of effectiveness of the compounds tested for each species was hexanal > hexanal + hexan-1-ol > hexan-1-ol. Neither hexanal, hexan-1-ol nor hexanal + hexan-1-ol was as effective in interrupting pheromone responses of D. frontalis as verbenone, a known inhibitor of this species. Other than interspecific chemical signals, this is the first report of an interruptant for Ips species, and the only report of a pheromone interruptant active for both Ips and Dendroctonus species.