Displacement of Tetropium cinnamopterum (Coleoptera: Cerambycidae) by Its Invasive Congener Tetropium fuscum

Asymmetric Synthesis of Contact Sex Pheromone of Tetropium fuscum and Its Enantiomer

Tetropium fuscum is a harmful forest pest and attacks spruces. The contact sex pheromone of this pest, (S)-11-methyl-heptacosane, and its enantiomer were synthesized via Evans' chiral auxiliaries. The key steps of this approach included acylation of carboxylic acid, diastereoselective methylation of oxazolidinone amide, and Wittig coupling of the aldehyde with chiral phosphonium salt. The synthetic pheromones would have potential utility in the control of this pest.

Mate choice errors may contribute to slow spread of an invasive Eurasian longhorn beetle in North America

Tetropium fuscum (Coleoptera: Cerambycidae) is a Eurasian longhorn beetle and forest pest that first became invasive to Nova Scotia, Canada around 1990. In the time since its introduction, T. fuscum has spread only about 150 km from its point of introduction. In its invasive range, T. fuscum co-exists with its congener Tetropium cinnamopterum. Although they are ecologically similar species, T. fuscum tends to infest healthier trees and has a smaller host range than T. cinnamopterum. If they successfully interbreed, this could lead to hybrid individuals that are more problematic than either parent species. On the other hand, if T. fuscum can make mating errors in the field, but is not producing hybrid offspring, then this waste of mating resources could help explain the slow spread of T. fuscum in North America. We conducted no-choice and choice mating experiments between T. fuscum and T. cinnamopterum males and females and determined that both T. fuscum and T. cinnamopterum males make mate-choice errors with heterospecific females in a laboratory setting. Our results suggest that mating errors may play a role in the slow spread of T. fuscum in North America.

Fuscumol and Geranylacetone as Pheromone Components of Californian Longhorn Beetles (Coleoptera: Cerambycidae) in the Subfamily Spondylidinae

In field trials testing attraction of cerambycid beetles to a blend of known pheromone components plus host plant volatiles, several species in the subfamily Spondylidinae were attracted to baited traps, suggesting that one or more components of the blend might constitute their pheromones. Here, we describe laboratory and field experiments aimed at identifying the actual pheromone components produced by these species. Analysis of headspace odors collected from male Tetropium abietis (Fall) (Coleoptera: Cerambycidae) contained (S)-fuscumol as a single component, whereas Asemum nitidum (LeConte) (Coleoptera: Cerambycidae) males produced both (S)-fuscumol and geranylacetone, and Asemum caseyi (Linsley) (Coleoptera: Cerambycidae) produced only geranylacetone. In field trials testing fuscumol, fuscumol acetate, and geranylacetone as individual components or in blends, in combination with host plant volatiles, A. nitidum were attracted to blends of fuscumol and geranylacetone, T. abietis were attracted to fuscumol alone, and A. caseyi were attracted to geranylacetone alone. Fuscumol acetate did not appear to be either attractive or inhibitory. These results, along with previous catches of spondylidine species in traps baited with fuscumol, provide evidence that fuscumol and geranylacetone are likely to be relatively common pheromone structures for species in the subfamily Spondylidinae.

Developmental Costs of Biological Invasion: The Exotic Wood Borer Tetropium fuscum (Coleoptera: Cerambycidae) is More Asymmetric and Smaller in Invaded Area

Biological invasions provide a unique opportunity to gain insight into basic biological processes occurring under new circumstances. During the process of establishment, exotic species are exposed to various stressors which may affect their development. Presence of the stressors is often detected by measurements of left-right body asymmetry, which consists of two main components: fluctuating asymmetry and directional asymmetry. Fluctuating asymmetry constitutes random differences between the two body sides, whereas directional asymmetry occurs when a particular trait is bigger on one of the sides. The relation between these two asymmetry components is still not fully understood. Our goal was to investigate the potential differences in asymmetry patterns between native and invasive populations of Tetropium fuscum (Fabr. 1787) (Coleoptera: Cerambycidae), a harmful forest pest native to Europe and introduced to North America. Wing asymmetry assessment was based on the geometric morphometrics of hind wings. We found that specimens from invaded area were markedly smaller and have more asymmetric wings than individuals from native population, suggesting some unfavorable conditions in the invaded area. Moreover, we found significant directional asymmetry in the native but not in the invasive population. On the other hand, differences between left and right hind wings were similar in the native and invasive populations, in terms of direction. This suggests that a high level of fluctuating asymmetry in the invasive population may blur the intrinsic directional asymmetry and hinder its detection. Our data show that fluctuating asymmetry has a potential as an indicator of developmental stress in invasive species.

Impact of an Invasive Longhorned Beetle, Tetropium fuscum (Coleoptera: Cerambycidae), on Community Structure of Subcortical and Wood-Associated Insects in Eastern Canada

Tetropium fuscum (Fabricius) (Coleoptera: Cerambycidae), a phloem-feeding and wood-boring beetle introduced from Eurasia, attacks spruce in eastern Canada alongside its native congener Tetropium cinnamopterum Kirby. We reared phloem- and wood-feeding insects (and their predators) from bolts of red and Norway spruce (Picea rubens and Picea abies) in Nova Scotia, comparing insect communities between bolts with added eggs of T. fuscum or T. cinnamopterum and bolts without added Tetropium (controls). We tested for impacts of each Tetropium on insect community structure (Simpson's diversity, richness, and evenness). We also asked whether, consistent with Darwin's Naturalization Hypothesis, Tetropium spp. would have greater impacts on emergence of its closer relatives (which might be most likely to compete and/or share natural enemies). Addition of Tetropium eggs (either species) to bolts lowered insect diversity in both host trees. Both richness and evenness components of diversity were always lower in +Tetropium treatments, although different components reached statistical significance in different Tetropium species × host combinations. Addition of Tetropium spp. significantly reduced emergence of some species: Evodinus monticola (Randall) (Coleoptera: Cerambycidae) was reduced by T. fuscum on both hosts and by T. cinnamopterum on Norway spruce; Hylobius congener Dalla Torre, Schenkling, and Marshall was reduced by T. fuscum on red spruce; and Xylophagus sp. (Diptera: Xylophagidae) was reduced by T. cinnamopterum on Norway spruce. However, there was no relationship between Tetropium's impact on a community member and their phylogenetic relatedness, and the overall impacts of Tetropium presence were not very different between T. fuscum and T. cinnamopterum.

Sex and Aggregation-Sex Pheromones of Cerambycid Beetles: Basic Science and Practical Applications

Research since 2004 has shown that the use of volatile attractants and pheromones is widespread in the large beetle family Cerambycidae, with pheromones now identified from more than 100 species, and likely pheromones for many more. The pheromones identified to date from species in the subfamilies Cerambycinae, Spondylidinae, and Lamiinae are all male-produced aggregation-sex pheromones that attract both sexes, whereas all known examples for species in the subfamilies Prioninae and Lepturinae are female-produced sex pheromones that attract only males. Here, we summarize the chemistry of the known pheromones, and the optimal methods for their collection, analysis, and synthesis. Attraction of cerambycids to host plant volatiles, interactions between their pheromones and host plant volatiles, and the implications of pheromone chemistry for invasion biology are discussed. We also describe optimized traps, lures, and operational parameters for practical applications of the pheromones in detection, sampling, and management of cerambycids.