Identification of the Aggregation-sex Pheromone of the Cerambycid Beetle Phymatodes pusillus ssp. pusillus and Evidence of a Synergistic Effect from a Heterospecific Pheromone Component

Abstract

The longhorn beetle Phymatodes (Poecilium) pusillus ssp. pusillus is a rare, elusive species that is included on Red Lists of threatened species. Previously, 1-hexanol and 1-butanol were reported as putative components of the aggregation-sex pheromone of this species, but behavioral assays to confirm this have not been performed. In this study, we undertook a comprehensive examination of P. p. pusillus to verify the presence of a pheromone. Adult beetles were reared from colonized wood and used for headspace sampling. Analyses by gas chromatography-mass spectrometry revealed that two compounds were present in large quantities in the extracts of males, but absent in extracts from females. Male and female antennae showed repeatable responses to the two compounds in electrophysiological recordings. Using synthetic standards, we were able to identify the compounds as 1-hexanol and 2-methyl-1-butanol. A field bioassay demonstrated that the two compounds were unattractive when applied singly, but elicited significant attraction of female and male beetles when applied in blends of different ratios. We also found that the species exhibited significant attraction to a blend of 3-hydroxy-2-hexanone and 2-methyl-1-butanol, which is the aggregation-sex pheromone of at least two closely related and sympatric species. The presence of the heterospecific component 3-hydroxy-2-hexanone synergized a response to 2-methyl-1-butanol. The pheromone of these species may function as a host cue for P. p. pusillus as the three species have similar phenology and substrate demands. The aggregation-sex pheromone of P. p. pusillus can be used for population monitoring and as a tool to study the general ecology and conservation requirements of this rare species.

The aggregation-sex pheromones of the cerambycid beetles Anaglyptus mysticus and Xylotrechus antilope ssp. antilope: new model species for insect conservation through pheromone-based monitoring

“…Detailed specifications of the materials and techniques used for the headspace sampling can be found in Molander and Larsson (2018). Briefly, collectors consisted of Pora-pak™ Q adsorbent, enclosed in Teflon ® tubing, and attached with Teflon ® thread-sealing tape to one of the two top openings of each glass bottle.…”

“…5). Cross-attraction to the pheromone components of heterospecifics is common in the subfamily Cerambycinae, and the pheromones of other species could function as cues signaling the location of suitable substrates for species with similar host requirements (Hanks et al 2007;Molander and Larsson 2018). However, using the species' specific aggregation-sex pheromone, rather than more generic attractants, can clearly be important to maximize sensitivity during surveys, particularly at low population densities (cf.…”

“…dimorphus (Ray et al 2014), Dryobius sexnotatus (Diesel et al 2017), Rosalia alpina (Žunič Kosi et al 2017), Phymatodes pusillus ssp. pusillus (Molander and Larsson 2018), and Plagionotus detritus ssp. detritus (Molander et al 2019).…”

Identification of the aggregation-sex pheromone of Plagionotus arcuatus ssp. arcuatus (Coleoptera: Cerambycidae) from two geographically separated European populations

“…In Sweden, beetles were trapped with custom-built flightintercept traps consisting of plastic cross-vane panels mounted on a funnel with a collecting jar below, and a top cover for rain protection (for details, see Molander and Larsson 2018). The panels and the inside of the funnel were coated with Fluon® (polytetrafluoroethylene dispersion, 60 w/w% in H 2 O, Sigma-Aldrich, St. Louis, MO, USA, diluted 1:1 with water).…”

Identification and Synthesis of Putative Pheromone Components of the Threatened Salt Marsh Bagworm Moth, Whittleia retiella (Lepidoptera: Psychidae)

“…These include scarabaeids such as the hermit beetle species Osmoderma eremita and Osmoderma barnabita (Larsson et al 2003;Svensson et al 2009), which Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10886-020-01145-x) contains supplementary material, which is available to authorized users. constituted the first model species for pheromone identifications specifically for conservation purposes, and the noble chafer Gnorimus nobilis (Harvey et al 2018), several click beetle species such as Elater ferrgineus (Tolasch et al 2007), Betarmon bisbimaculatus (Koenig et al 2015), and Idolus picipennis (Koenig et al 2016) and longhorn beetles such as Prionus coriarius (Barbour et al 2011), Rosalia alpina (Kosi et al 2017), Phymatodes pusillus (Molander and Larsson 2018), and Plagionotus detritus (Molander et al 2019). To date, only a limited number of rare and endangered moth species have been investigated e.g.…”