Isolation and identification of a male-produced aggregation-sex pheromone for the velvet longhorned beetle, Trichoferus campestris

Ann M Ray,Yunfan Zou,Jocelyn G Millar,Kristopher Watson,Joseph A Francese,Damon J Crook

doi:10.1038/s41598-019-41047-x

Ann M Ray, Yunfan Zou + Show 4 more

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https://doi.org/10.1038/s41598-019-41047-x

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Journal: Scientific Reports	Publication Date: Mar 14, 2019
Citations: 14	License type: open-access

Affiliation: University of California, Riverside

Abstract

The velvet longhorned beetle, Trichoferus campestris (Faldermann) (“VLB”; Coleoptera: Cerambycidae), is native to eastern Asia where it infests and damages a wide range of deciduous and coniferous tree species, including orchard and timber species. Immature stages of VLB are transported to new countries via international commerce, and populations have established outside the native range of the species. Here, we show that identification of pheromones of invasive pest species can be expedited by knowledge of the semiochemistry of related taxa. Histological sectioning revealed subcuticular, male-specific prothoracic glands connected to pits in the cuticle, which, in related species, are diagnostic for production of male-produced aggregation-sex pheromones, usually characterized by 2,3-alkanediol/hydroxyketone structural motifs. However, in preliminary field bioassays, beetles were not attracted by any known cerambycid pheromones. Subsequently, we identified a novel variant of the hydroxyketone motif (“trichoferone”) from headspace volatiles of males. In field bioassays, synthetic trichoferone was more attractive to both sexes of VLB than previously developed high-release-rate ethanol lures, and attraction was strongly female biased. This study demonstrated the utility of the prothoracic gland trait for predicting pheromone use in cerambycid species in the subfamily Cerambycinae, and that identification of pheromones of novel species can be expedited by knowledge of pheromones of related species. Trichoferone should prove to be a valuable tool for detection of VLB in regions where the beetle is or may become established.

Highlights

Non-native woodboring insects pose a major threat to the health and biodiversity of natural and managed forest ecosystems worldwide[1,2,3]
These efforts can be accelerated by exploiting what is known about the semiochemistry of related species[17,18], because pheromone structures are often conserved among related insect taxa
The experiments described here indicate that male VLB produce a sex-specific aggregation-sex pheromone[12] comprising two isomers of 2-hydroxy-4-methyl-1-phenylhexan-3-one in an approximately 3:1 ratio

Summary

Introduction

Non-native woodboring insects pose a major threat to the health and biodiversity of natural and managed forest ecosystems worldwide[1,2,3]. Volatile pheromones[12] are widely used as tools for monitoring and control of insect pests, and traps baited with cerambycid pheromones have been used successfully in surveys for longhorned beetles in both managed and natural forests[13]. To maximize the possibility of eradicating exotic pests, it is critical that pheromones or other attractants be identified and deployed by regulatory agencies as soon as possible after the initial discovery of an incipient infestation[11]. In cerambycids, these efforts can be accelerated by exploiting what is known about the semiochemistry of related species[17,18], because pheromone structures are often conserved among related insect taxa. The potential economic damage by VLB in North America is estimated to be high because of the broad host range of the beetle, and because VLB is a pest both in its native range and in areas where it has become established[24,27]

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