Pheromone Composition and Chemical Ecology of Six Species of Cerambycid Beetles in the Subfamily Lamiinae

Exploring the Nature of Arhopalus ferus (Coleoptera: Cerambycidae: Spondylidinae) Pheromone Attraction

Cerambycid species of the Spondylidinae subfamily are distributed worldwide and are known for being prolific invaders that infest conifers. In New Zealand, Arhopalus ferus (Mulsant), the burnt pine longhorn beetle, is well-established and requires monitoring at high-risk sites such as ports, airports, and sawmills as part of the requirements to meet pine log export standards set by the New Zealand Ministry of Primary Industries (MPI). Currently, its surveillance relies on traps baited with host volatiles (i.e., ethanol and α-pinene). We used volatile collections from adult beetles, electroantennograms, and field trapping bioassays to identify the pheromones emitted by the burnt pine longhorn beetle A. ferus and their effects on its behaviour. We show that A. ferus males emit mainly (E)-fuscumol and geranylacetone, as well as the minor components, α-terpinene and p-mentha-1,3,8-triene, and that all four compounds elicit a dose-dependent response in antennae of both sexes. Traps baited with the binary combination of geranylacetone plus fuscumol captured significantly more female A. ferus than did unbaited traps in two of three field experiments. α-Terpinene did not affect A. ferus trap catches and effects of p-mentha-1,3,8-triene on trap catch were not determined. Our findings provide further evidence of the use of fuscumol and geranylacetone as aggregation-sex pheromones by longhorn beetles in the Spondylidinae subfamily, and suggest that their deployment in survey traps may improve the efficacy of A. ferus monitoring in New Zealand and elsewhere.

New Canadian and Provincial Records of Coleoptera Resulting from Annual Canadian Food Inspection Agency Surveillance for Detection of Non-Native, Potentially Invasive Forest Insects

The arrival and establishment of adventive, invasive forest insects are a threat to the health, diversity, and productivity of forests in Canada and the world at large, and their early detection is essential for successful eradication and management. For that reason, the Canadian Food Inspection Agency (CFIA) conducts annual surveys at high risk sites such as international ports and freight terminals, industrial zones, and disposal sites for solid wood packaging material using two methods: (1) semiochemical-baited traps deployed in a total of about 63-80 sites per year in British Columbia (BC), Ontario (ON), Quebec (QC), New Brunswick (NB), Nova Scotia (NS), and Newfoundland and Labrador (NL); and (2) rearing of insects from bolts collected from stressed trees and incubated in modified shipping containers in four cities (Vancouver, Toronto, Montreal, and Halifax). We report 31 new Canadian provincial records of Coleoptera from surveys conducted in 2011-2021, including 13 new records for Canada and 9 species adventive to North America (indicated by †). Nine of the new Canadian records were native North American species previously detected only south of the border. All but three species belong to the Curculionidae family and most of these were in the subfamily Scolytinae. The records include: Xenomelanophila miranda (LeConte) (Canada, BC) (Buprestidae: Buprestinae); Neoclytus mucronatus mucronatus (Fabricius) (BC) (Cerambycidae: Cerambycinae); Amphicerus cornutus (Pallas) (Canada, BC) (Bostrichidae: Bostrichinae); Mecinus janthinus (Germar)† (ON) (Curculionidae: Curculioninae); Aulacobaris lepidii (Germar)† (Canada, ON); Buchananius striatus (LeConte) (ON) (Curculionidae: Baridinae); Cylindrocopturus binotatus LeConte (Canada, ON) (Curculionidae: Conoderinae); Himatium errans LeConte (ON); Phloeophagus canadensis Van Dyke (ON); Rhyncolus spretus Casey (Canada, BC); Stenomimus pallidus (Boheman) (Canada, ON); Tomolips quercicola (Boheman) (Canada, ON) (Curculionidae: Cossoninae); Strophosoma melanogrammum (Forster)† (NB) (Curculionidae: Entiminae); Conotrachelus aratus (Germar) (ON) (Curculionidae: Molytinae); Anisandrus maiche Stark† (Canada, ON, QC); Cnesinus strigicollis LeConte (Canada, ON); Cyclorhipidion pelliculosum (Eichhoff)† (Canada, ON, QC); Hylesinus fasciatus LeConte (QC); Hylesinus pruinosus Eichhoff (QC); Hypothenemus interstitialis (Hopkins) (Canada, ON); Lymantor alaskanus Wood (BC); Pityogenes bidentatus (Herbst)† (Canada, ON); Scolytus mali (Bechstein)† (BC); Scolytus schevyrewi Semenov† (QC); Trypodendron scabricollis (LeConte) (Canada, ON); Trypophloeus populi Hopkins (QC); Xylechinus americanus Blackman (NFLB); and Xylosandrus crassiusculus (Motschulsky)† (BC, QC) (Curculionidae: Scolytinae). We also provide additional data confirming the presence of the adventive Hylastes opacus Erichson† in NS. Rearing of insects from bolts accounted for two new records (H. pruinosus, R. spretus) and trapping accounted for the remainder. These surveys not only assist our efforts to manage forest insects by documenting new species introductions and apparent range expansions but also increase our knowledge of biodiversity.

Cerambycid Pheromones 3,2-Hydroxyketones Affect Catches of Some Bark and Ambrosia Beetles (Coleoptera: Curculionidae) in Ethanol-Baited Multiple-Funnel Traps in Southeastern United States

In 2012-2013, we assessed the interactive effects of the cerambycid pheromones syn-2,3-hexanediol, 3-hydroxyhexan-2-one, and 3-hydroxyoctan-2-one on catches of bark and ambrosia beetles (Coleoptera: Curculionidae) in ethanol-baited multiple-funnel traps in north Georgia and South Carolina. We found that catches for nine of eleven species of ambrosia beetles in ethanol-baited traps were either unaffected or enhanced by the addition of 3,2-hydroxyketones. Similarly catches of five species of bark beetles were either unaffected or enhanced by the addition of 3,2-hydroxyketones. In particular, catches of Xylosandrus crassiusculus (Motschulsky), Cnestus mutilatus (Blandford), and Monarthrum fasciatum (Say) in ethanol-baited traps increased with the addition of 3-hydroxyhexan-2-one and/or 3-hydroxyoctan-2-one. Catches of the bark beetles Hylocurus rudis (LeConte) and Hypothenemus rotundicollis (Eichhoff) were enhanced by the addition of 3-hydroxyhexan-2-one and 3-hydroxyoctan-2-one, respectively. syn-2,3-Hexanediol had no effect on catches of bark and ambrosia beetles in ethanol-baited traps. Our data provide support for the use of ethanol + cerambycid pheromones for targeting non-native species of bark and ambrosia beetles as well as cerambycids in detection programs.

A Novel Trisubstituted Tetrahydropyran as a Possible Pheromone Component for the South American Cerambycid Beetle Macropophora accentifer

A novel trisubstituted tetrahydropyran was isolated and identified from the sex-specific volatiles produced by males of the cerambycid beetle Macropophora accentifer (Olivier), a serious pest of citrus and other fruit crops in South America. The compound was the major component in the headspace volatiles, and it was synthesized in racemic form. However, in field trials, the racemate was only weakly attractive to beetles of both sexes, suggesting that attraction might be inhibited by the presence of the "unnatural" enantiomer in the racemate. Alternatively, the male-produced volatiles contained a number of minor and trace components, including a compound tentatively identified as a homolog of the major component, as well as a number of unsaturated 8-carbon alcohols and aldehydes. Further work is required to conclusively identify and synthesize these minor components, to determine whether one or more of them are crucial components of the active pheromone blend for this species.

Interactions Between syn- and anti-2,3-Hexanediol Lures on Trap Catches of Woodboring Beetles and Associates in Southeastern United States

In 2016, we conducted three experiments to clarify the effects of 2,3-hexanediols isomers on trap catches of Neoclytus acuminatus (F.) (Coleoptera: Cerambycidae). We also noted the effects of the isomers on trap catches of other cerambycids and associated species of predators and competitors. Catches of N. acuminatus in traps baited with ethanol + syn-2,3-hexanediol + racemic 3-hydroxyoctan-2-one were reduced with the addition of anti-2,3-hexanediol, an attractant for Curius dentatus Newman (Coleoptera: Cerambycidae). A fourth experiment conducted in 2017 verified that racemic 3-hydroxyoctan-2-one increases catches of N. acuminatus in traps baited with ethanol + syn-2,3-hexanediol. The addition of anti-2,3-hexanediol increased catches of Knulliana cincta (Drury) (Coleoptera: Cerambycidae) in traps baited with ethanol + racemic 3-hydroxyoctan-2-one, whereas attraction of Neoclytus scutellaris (Olivier) to traps baited with ethanol + racemic 3-hydroxyhexan-2-one was reduced by syn-2,3-hexanediol. Trap catches of the beetle predators Chariessa pilosa (Forster), Enoclerus ichneumonus (F.), and Madoniella dislocata (Say) (Coleoptera: Cleridae) were affected by 2,3-hexanediol isomers, whereas other common predators were unaffected by the isomers. Attraction of the bostrichid Xylobiops basilaris (Say) (Coleoptera: Bostrichidae) was increased by the 2,3-hexanediols; the relative effect of the two isomeric blends was dependent on trap co-baits of 3-hydroxy-2-ketones. The two enantiomeric blends of 2,3-hexanediol had minimal effects on catches of most species of ambrosia beetles, whereas the 3-hydroxy-2-ketones affected trap catches of some species.

Effect of Host Volatile Release Rate and Racemic Fuscumol on Trap Catch of Hylurgus ligniperda, Hylastes ater (Coleoptera: Curculionidae), and Arhopalus ferus (Coleoptera: Cerambycidae)

Early detection of bark- and wood-boring beetles is critical to support the eradication of recently established populations in novel regions. Flight intercept traps baited with semiochemical lures are essential for surveillance and population monitoring of introduced insects. We present laboratory and field data to test potential improvements in trap sensitivity to detect Hylastes ater (Paykull), Hylurgus ligniperda (Fabricius) (Coleoptera:Scolytinae), and Arhopalus ferus (Mulsant) (Coleoptera:Cerambycidae). We evaluated the effects of type and permeability of plastic material on release rates of host-plant volatiles and the addition of the pheromone racemic E-fuscumol on beetle species catch within an exotic Pinus radiata (D. Don) plantation forest. We trapped 228,278 H. ligniperda, 91 H. ater, and 2,504 A. ferus over two experiments. Our results show strong attraction of H. ligniperda to host-plant volatiles with a positive relationship between increased release rates and trap catch. H. ater follows this trend, with attraction to ethanol and (-)-β-pinene. H. ligniperda was more strongly attracted to host volatiles than H. ater, the average ratio between baited and unbaited traps being 51.25:1 and 3.75:1, respectively for each species. There was no effect of host-plant volatiles or release rate on A. ferus catch, but a weak attraction by A. ferus to racemic E-fuscumol. Overall, we demonstrate species-specific differences in Coleoptera attraction to host-plant volatile release rates and semiochemical blends. Results demonstrate mechanisms to improve trap catch of H. ligniperda and H. ater. Racemic E-fuscumol shows some promise for A. ferus, but further investigation is required to determine whether chirality affects attraction.

Enantioselective sensing of insect pheromones in water

An arrayed combination of water-soluble deep cavitands and cationic dyes has been shown to optically sense insect pheromones at micromolar concentration in water. Machine learning approaches were used to optimize the most effective array components, which allows differentiation between small structural differences in targets, including between different diastereomers, even though the pheromones have no innate chromophore. When combined with chiral additives, enantiodiscrimination is possible, dependent on the size and shape of the pheromone.

3-Hydroxyhexan-2-one and 3-Methylthiopropan-1-ol as Pheromone Candidates for the South American Cerambycid Beetles Stizocera phtisica and Chydarteres dimidiatus dimidiatus, and Six Related Species

Here, we study the pheromone chemistry of two South American cerambycid beetle species, and their behavioral responses to candidate pheromone components. Adult males of Stizocera phtisica Gounelle (subfamily Cerambycinae: tribe Elaphidiini) produced a sex-specific blend of (R)-3-hydroxyhexan-2-one with lesser amounts of 3-methylthiopropan-1-ol. In field bioassays, traps baited with racemic 3-hydroxyhexan-2-one and 3-methylthiopropan-1-ol did not catch conspecific beetles, but did catch both sexes of a sympatric species, Chydarteres dimidiatus dimidiatus (F.) (Cerambycinae: Trachyderini). We found that males of this species also produce (R)-3-hydroxyhexan-2-one and 3-methylthiopropan-1-ol, and small amounts of 2-phenylethanol. Subsequent bioassays with these compounds showed that a blend of 3-hydroxyhexan-2-one and 3-methylthiopropan-1-ol constitutes the aggregation-sex pheromone of C. d. dimidiatus, with 2-phenylethanol not influencing the attraction of conspecifics. During the field bioassays, six other species in the Cerambycinae also were caught in significant numbers, including Aglaoschema ventrale (Germar) (tribe Compsocerini), congeners Chrysoprasis aurigena (Germar), Chrysoprasis linearis Bates, and an unidentified Chrysoprasis species (Dichophyiini), and Cotyclytus curvatus (Germar) and Itaclytus olivaceus (Laporte & Gory) (both Clytini), suggesting that one or more of the compounds tested are also pheromone components for these species.

Response of native and exotic longhorn beetles to common pheromone components provides partial support for the pheromone-free space hypothesis

Longhorn beetles are among the most important groups of invasive forest insects worldwide. In parallel, they represent one of the most well-studied insect groups in terms of chemical ecology. Longhorn beetle aggregation-sex pheromones are commonly used as trap lures for specific and generic surveillance programs at points of entry and may play a key role in determining the success or failure of exotic species establishment. An exotic species might be more likely to establish in a novel habitat if it relies on a pheromone channel that is different to that of native species active at the same time of year and day, allowing for unhindered mate location (i.e., pheromone-free space hypothesis). In this study, we first tested the attractiveness of single pheromone components (i.e., racemic 3-hydroxyhexan-2-one, racemic 3-hydroxyoctan-2-one, and syn-2,3-hexanediol), and their binary and tertiary combinations, to native and exotic longhorn beetle species in Canada and Italy. Second, we exploited trap catches to determine their seasonal flight activity. Third, we used pheromone-baited "timer traps" to determine longhorn beetle daily flight activity. The response to single pheromones and their combinations was mostly species specific but the combination of more than one pheromone component allowed catch of multiple species simultaneously in Italy. The response of the exotic species to pheromone components, coupled with results on seasonal and daily flight activity, provided partial support for the pheromone-free space hypothesis. This study aids in the understanding of longhorn beetle chemical ecology and confirms that pheromones can play a key role in longhorn beetle invasions.

Rapid Assessment of Cerambycid Beetle Biodiversity in a Tropical Rainforest in Yunnan Province, China, Using a Multicomponent Pheromone Lure

Simple Summary

The Cerambycidae comprise a diverse (>35,000 species) family of wood-boring beetles. Many are of concern as invasive species because their long-lived larvae are readily transported around the world concealed in wooden products and packing materials. Over the past two decades, our understanding of cerambycid pheromone chemistry has advanced rapidly, with pheromone structures now described for several hundred species. Furthermore, mixtures of cerambycid pheromones have been shown to potentially act as effective multispecies lures. In this study, traps baited with generic lures deployed at ground level and in the tree canopy in 22 randomly located permanent plots in a nature reserve in Yunnan, China, captured 4541 beetles of 71 species. Using Hierarchical Modeling of Species Communities, we developed informative models for 18 species and demonstrated that trap height, slope, elevation, and leaf-area index were important determinants of cerambycid beetle distribution. Our results demonstrate the potential for using generic lures to detect and monitor cerambycid populations at ports of entry, and for the study of cerambycid beetle ecology.

Abstract

The Cerambycidae comprise a large and ecologically important family of wood-boring beetles. The purpose of this study was to examine the effectiveness of a generic lure as a potential monitoring tool. Working in a subtropical forest in southwest China, we set traps baited with generic lures at ground level (1 m) and canopy height (~18 m) across 22 randomly located forest plots (12 regenerating forest, 10 mature forest). Three stations were established per plot and each plot was trapped for 7 days in May–June 2013. In total, 4541 beetles of 71 species were caught, including 26 species with 10 or more individuals. We used Hierarchical Modeling of Species Communities (HMSC) to analyze the data and produced informative models for 18 species, showing that trap height, slope, elevation, and leaf-area index were important determinants of cerambycid distribution. Our results demonstrate the potential for using generic lures to detect and monitor cerambycid populations, both for regulatory purposes and for the study of cerambycid beetle ecology. Further research should focus on refining lure blends, and on repeated sampling to determine temporal and spatial dynamics of cerambycid communities.

Drug Discovery Insights from Medicinal Beetles in Traditional Chinese Medicine

Traditional Chinese medicine (TCM) was the primary source of medical treatment for the people inhabiting East Asia for thousands of years. These ancient practices have incorporated a wide variety of materia medica including plants, animals and minerals. As modern sciences, including natural products chemistry, emerged, there became increasing efforts to explore the chemistry of this materia medica to find molecules responsible for their traditional use. Insects, including beetles have played an important role in TCM. In our survey of texts and review articles on TCM materia medica, we found 48 species of beetles from 34 genera in 14 different families that are used in TCM. This review covers the chemistry known from the beetles used in TCM, or in cases where a species used in these practices has not been chemically studied, we discuss the chemistry of closely related beetles. We also found several documented uses of beetles in Traditional Korean Medicine (TKM), and included them where appropriate. There are 129 chemical constituents of beetles discussed.

Complex Blends of Synthetic Pheromones are Effective Multi-Species Attractants for Longhorned Beetles (Coleoptera: Cerambycidae)

The wood-boring larvae of longhorned beetles (Coleoptera: Cerambycidae) can be important pests of woody plants, particularly as invasive species introduced by international commerce. Previous research has revealed that cerambycid species native to different parts of the world often share the same aggregation-sex pheromones and that pheromones of different species can be combined to create multi-species attractants that would be advantageous for surveillance monitoring for a number of species simultaneously. To explore the extent to which these chemicals can be combined into single lures, we developed four different blends of six to eight compounds and tested their effects as attractants for a community of longhorned beetle species in Iowa. The blends included known pheromones of species native to the study site, as well as pheromones identified from cerambycid species native to other parts of the world. The experiment confirmed that several cerambycid species were attracted by specific blends, in accordance with their known pheromone chemistry, and despite the presence of pheromone components of heterospecifics. This finding lends further support to developing multi-component blends that can effectively monitor for new incursions of multiple exotic species concurrently.

Sulcatol: Enantiospecific Attractant for Monarthrum mali (Coleoptera: Curculionidae: Scolytinae), Leptostylus asperatus (Coleoptera: Cerambycidae) and Associated Predators

In 2014-2019, we conducted six experiments in north-central Georgia in an attempt to verify the aggregation pheromone response of the ambrosia beetle Gnathotrichus materiarius (Fitch) (Coleoptera: Curculionidae: Scolytinae: Scolytini: Corthylina) to sulcatol known to be produced by male G. materiarius; we failed to catch any G. materiarius. However, we did find that another corthyline ambrosia beetle species Monarthrum mali (Fitch) was attracted to (R)-(-)-sulcatol, whereas the longhorn beetle Leptostylus asperatus (Haldeman) (Coleoptera: Cerambycidae: Lamiinae) was attracted to (S)-(+)-sulcatol. Attraction of both species was unaffected by the respective antipodes. Ethanol enhanced attraction of both species to traps baited with sulcatol. In at least one experiment, attraction to ethanol-baited traps was enhanced by sulcatol for Xylosandrus crassiusculus (Motschulsky), Xyleborus spp., and Hypothenemus spp. but reduced for Cnestus mutilatus (Blandford) (Coleoptera: Curculionidae: Scolytinae). Additionally, traps baited with ethanol and racemic sulcatol [50% (S)-(+): 50% (R)-(-)] caught the greatest numbers of four species of beetle predators: Coptodera aerata Dejean (Coleoptera: Carabidae), Colydium lineola Say (Coleoptera: Zopheridae), Madoniella dislocata (Say), and Pyticeroides laticornis (Say) (Coleoptera: Cleridae). Ethanol but not sulcatol attracted Temnoscheila virescens (F.) (Coleoptera: Trogossitidae). Information on interspecific relationships within forested communities may help us to better determine the roles of these species in maintaining stable and resilient forested ecosystems.