Attraction of <I>Ips pini</I> (Coleoptera: Scolytinae) and Its Predators to Natural Attractants and Synthetic Semiochemicals in Northern California: Implications for Population Monitoring

Abstract

Effective management of bark beetles (Coleoptera: Curculionidae, Scolytinae) relies on accurate assessments of pest and predator populations. Semiochemicals provide a powerful tool for attracting bark beetles and associated predators, but the extent to which trap catches reßect actual population densities are poorly understood. We conducted Þeld experiments in California during 2 consecutive yr to determine how attraction of Ips pini (Say) and its major predators to synthetic pheromones vary from each other and from attraction to natural volatiles emitted from colonized hosts. Synthetic lures consisted of different ratios of the (ϩ) and (Ð) enantiomers of ipsdienol, the primary pheromone component of I. pini, with or without lanierone, an additional component that synergizes attraction in some populations. I. pini was consistently attracted to either 3(ϩ)/97(Ϫ) ipsdienol or infested host plant material. Lanierone had no effect on the attraction of I. pini. Coleopteran predators showed a range of responses, more of which coincided with I. pini. Temnochila chlorodia (Mannerheim) (Trogositidae) was attracted to infested host materials and all synthetic lures. Enoclerus lecontei (Wolcott) (Cleridae) preferentially responded to higher ratios of (ϩ)-ipsdienol, and its attraction was strongly enhanced by lanierone. Enoclerus sphegeus F. was most attracted to infested hosts and exhibited a preference for (Ϫ)-over (ϩ)-ipsdienol. Our results suggest that preferences of bark beetles and predators for bark beetle pheromones at the regional scale should be considered before deploying semiochemicals. These results are also consistent with a model of co-evolving responses to pheromones by predators and their prey. The roles of plant volatiles should be further investigated, both to improve monitoring programs and from an ecological perspective.

Comparison of Naturally and Synthetically Baited Spruce Beetle Trapping Systems in the Central Rocky Mountains

“…Beetle response to these traps is species dependent and can vary for conspeciÞcs in differing geographies. For example, Aukema et al (2000) determined that certain synthetic lures with funnel traps caught more Ips pini (Say) than traps baited with infested red pine, Pinus resinosa Soland, bolts in Wisconsin, whereas an otherwise similar study found equivalent trapping performance among the two trapping systems for I. pini in California (Dahlsten et al 2004). Ips typographus (L.), much like the spruce beetle, prefers recently downed host material and trap trees substantially outperformed synthetically baited traps in at least two studies (Drumont et al 1992, Raty et al 1995.…”

Semiochemicals in the Natural History of Southern Pine Beetle Dendroctonus frontalis Zimmermann and Their Role in Pest Management

“…Investigations of predator-prey interactions in other bark beetle systems have suggested that disparities between the maximally attractive semiochemical blends for bark beetle prey and their predators may provide a "chemically mediated predator free space" that may have resulted from directional selection by predators on the pheromone composition of their prey Dahlsten et al, 2004). Such semiochemical-based predator escape may involve differing predator/prey responses to components of the prey's aggregation pheromone (Dahlsten et al, 2004;Raffa and Klepzig, 1989) as well as the host tree-produced pheromone synergists (Erbilgin and Raffa, 2001).…”

“…Such semiochemical-based predator escape may involve differing predator/prey responses to components of the prey's aggregation pheromone (Dahlsten et al, 2004;Raffa and Klepzig, 1989) as well as the host tree-produced pheromone synergists (Erbilgin and Raffa, 2001). In fact, T. dubius and their D. frontalis prey are not maximally attracted to the same semiochemical blend, suggesting a less-than-ideal "search image" is used by T. dubius in seeking its D. frontalis prey.…”

Using Generic Pheromone Lures to Expedite Identification of Aggregation Pheromones for the Cerambycid Beetles Xylotrechus nauticus, Phymatodes lecontei, and Neoclytus modestus modestus

“…T. chlorodia is a predator of scolytid beetles and is attracted by their pheromones (Bedard et al 1980;Seybold et al 1992;Dahlsten et al 2004). Consequently, it seems reasonable to suppose that it also might be attracted to volatiles associated with other potential prey.…”