Role of Ipsdienol, Ipsenol, and cis-Verbenol in chemical ecology of Ips avulsus, Ips calligraphus, and Ips grandicollis (Coleoptera: Curculionidae: Scolytinae)
ABSTRACT Stressed or damaged pine (Pinus sp.) trees in the southeastern United States are often colonized simultaneously by three southern Ips species (Coleoptera: Curculionidae: Scolytinae): small southern pine engraver, Ips avulsus (Eichhoff); sixspined ips, Ips calligraphus (Germar); and eastern fivespined ips, Ips grandicollis (Eichhoff). All three species mediate colonization of host material with volatile pheromones. All of the southern Ips produce cis-verbenol, and either ipsdienol or ipsenol, and electrophysiological studies have demonstrated that all three southern Ips are able to detect all three compounds. This study examined the role of ipsdienol, ipsenol, and cis-verbenol in the chemical ecology of the southern Ips in Georgia and Louisiana. The most attractive blends of pheromones, with the fewest number of components, were ipsdienol plus ipsenol for I. avulsus, cis-verbenol plus ipsdienol for I. calligraphus, and either cis-verbenol plus ipsenol or ipsdienol plus ipsenol for I. grandicollis. Cross-attraction of I. grandicollis to the pheromone blend most attractive to I. avulsus was observed. Although the presence of heterospecific pheromone reduced the catches of all three species (i.e., the tertiary blend captured fewer beetles than the most attractive binary blends) in both states (significantly in two cases), high numbers of all three species were still captured in traps baited with all three compounds. These results suggest that the pheromones cis-verbenol, ipsdienol, and ipsenol can be combined for monitoring all three species of the southern Ips simultaneously.