Attraction of <I>Ips pini</I> (Coleoptera: Scolytidae) and Its Predators to Various Enantiomeric Ratios of Ipsdienol and Lanierone in California: Implications for the Augmentation and Conservation of Natural Enemies

Abstract

Many natural enemies of bark beetles are attracted to bark beetle pheromones, and substantial numbers of them are removed along with the target pests in mass trap-out programs. Thus, additional information on bark beetle and predator behavior is needed to maximize trap-out of target pests while decreasing trapping of beneÞcial insects. Ips pini (Say) is the most widespread bark beetle associated with pine trees in the United States and Canada. Geographically distant populations vary considerably in their production of, and response to, different stereoisomers of their principal pheromone component, ipsdienol, and an additional pheromone component, lanierone. California populations of I. pini are attracted to 99.9%(Ð)-ipsdienol, and the presence of lanierone has no effect on attraction. We simulated trap-outs by conducting no-choice assays using three different ratios of (ϩ)/(Ϫ) enantiomers of ipsdienol with or without lanierone in the Þeld. Experiments were performed in mixed pine forests in northern California in 1997 and 1998. Experiments were performed twice each year to sample the two major ßight periods of I. pini. Ips pini and its predators showed temporal and behavioral differences in their attraction to lures. Lures that are preferred by I. pini, 3(ϩ)/97(Ϫ) ipsdienol with or without lanierone, selectively removed up to 5Ð7 times more pests than predators during early summer. Moreover, the ratios of pest to predators were much higher in the late than early summer, and pest numbers were as much as 282 times higher than predators. In contrast, lures most attractive to predators removed as much as 10 predators for each I. pini trapped. These results suggest that timely applications of carefully selected synthetic lures, in combination with other complementary forest management practices, can greatly improve trap-out programs for bark beetles and natural enemy conservation. In addition, behavioral differences in attraction suggest the potential for augmentation of natural enemies.

Attractive responses by Monochamus galloprovincialis (Col., Cerambycidae) to host and bark beetle semiochemicals

“…Kairomonal responses of bark beetle natural enemies to bark beetle semiochemicals and host volatiles are well known (e.g. Dahlsten, 1982;Grégoire et al, 1992;Ross and Daterman, 1995;Dahlsten et al, 2003;Schroeder, 2003). In this study high numbers of T. coerulea and T. formicarius were attracted and subsequently killed in traps baited with these stimuli.…”

Seasonal pheromone response by Ips pini in northern Arizona and western Montana, U.S.A.

“…Local variability within these larger geographically defined pheromone types has also been noted ( Miller et al , 1989;Herms et al , 1991;Miller et al , 1996 ). In addition, the strength of lanierone as a synergist varies geographically, with it being strongly synergistic in New York and Wisconsin, weakly synergistic in Montana and BC, and minimally synergistic in California Seybold et al , 1992;Miller et al , 1997;Dahlsten et al , 2003 ). Genetic evidence supports these pheromone-based population delineations ( Cognato et al , 1999;Domingue et al , 2006 ).…”

“…In addition to geographical differences in pheromone response, I. pini may also undergo a seasonal change in pheromone response ( Birch, 1974;Ayres et al , 2001;Dahlsten et al , 2003 ). This shift may involve a change in the preferred enantiomeric ratio of the attractant ipsdienol, as well as the selection for other semiochemical compounds, such as lanierone Seybold et al , 1992;Miller et al , 1997;Ayres et al , 2001;Dahlsten et al , 2003 ).…”

Respuesta de insectos descortezadores de pino y de sus depredadores a semioquímicos en el sur de México

“…tes mezclas enantioméricas separadas de ipsdienol e ipsenol, incluyendo la mezcla racémica usada en el presente trabajo (Dahlsten et al, 2003;Fettig et al, 2007 …”