Pinyon Engraver Beetle Acoustics: Stridulation Apparatus, Sound Production and Behavioral Response to Vibroacoustic Treatments in Logs.

Ivan Lukic,Evan M Hofstetter,Richard W Hofstetter,Carol L Bedoya

doi:10.3390/insects12060496

Ivan Lukic, Evan M Hofstetter + Show 2 more

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https://doi.org/10.3390/insects12060496

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Abstract

Simple SummaryAcoustic technology is a potential tool to protect wood materials and live trees from colonization by bark beetles and other wood-infesting insects. Bark beetles such as the pinyon engraver beetle Ips confusus use chemical and acoustic cues to communicate and to locate potential mates in trees. In this study, we describe the structures and airborne sounds produced by the pinyon engraver beetle, and test the efficacy of vibroacoustic treatments for tree protection against this beetle. Only female beetles possessed sound producing structures, located on the back of the head and inside the thorax. We analyzed and described the airborne sounds, called chirps, produced by females when held by tweezers or placed on their back. We tested a wide variety of vibroacoustic treatments played into logs but these sound treatments did not prevent male entry into logs and did not disrupt female–male interactions, female tunneling behavior, reproduction or egg laying. We suggest further studies if acoustic methods are to be utilized to control this bark beetle.Bark beetles are among the most influential biotic agents in conifer forests, and forest management often focuses on bark beetle chemical communication for tree protection. Although acoustic communication occurs in many bark beetle species, we have yet to utilize acoustic communication for bark beetle control. Here, we describe the stridulatory organs and ‘stress’ chirps of the pinyon engraver, Ips confusus, a significant pest and mortality agent of pinyon pine in western North America. Only females possessed stridulatory organs and their stress chirps varied significantly in duration, pulses per chirp, and dominant frequency. We tested an array of acoustic-vibrational treatments into logs but were unable to disrupt male entry into logs or alter female–male interactions, female tunneling, and female oviposition. We found acoustic–vibrational treatments had little effect on I. confusus behavior and suggest further studies if acoustic methods are to be utilized for bark beetle control.

Highlights

IntroductionMass aggregation pheromones are released by the pioneer sex which is male (e.g., Ips species) or female (e.g., Dendroctonus species) depending on the bark beetle genus [9,10]
Female Ips confusus possessed vertex-pronotal structures (Figure 2) that are consistent a male I. confusus was introduced into the log and a female beetle was with other Ips species [11,13,63]
Number of ridges in the pars stridens differs from published literature in that we found approximately twice as many ridges on I. confusus compared to I. pini measured by Sivalinghem [17] and

Summary

Introduction

Mass aggregation pheromones are released by the pioneer sex which is male (e.g., Ips species) or female (e.g., Dendroctonus species) depending on the bark beetle genus [9,10]. The non-pioneering sex typically has welldeveloped stridulatory structures [11,12] and will stridulate (i.e., produce sounds/vibrations) when arriving near or inside the gallery of a pioneer’s entry hole [13,14]. Bark beetle stridulation sounds influence pheromone production and composition of bark beetle partners within the tree. Dendroctonus bark beetles that stridulate near the entrance hole of a potential partner stimulates the beetle within the tunnel to alter the chemical composition or even stop production of their aggregation pheromone [28,29]

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