Sound-Triggered Production of Antiaggregation Pheromone Limits Overcrowding ofDendroctonus valensAttacking Pine Trees

Abstract

For insects that aggregate on host plants, both attraction and antiaggregation among conspecifics can be important mechanisms for overcoming host resistance and avoiding overcrowding, respectively. These mechanisms can involve multiple sensory modalities, such as sound and pheromones. We explored how acoustic and chemical signals are integrated by the bark beetle Dendroctonus valens to limit aggregation in China. In its native North American range, this insect conducts nonlethal attacks on weakened trees at very low densities, but in its introduced zone in China, it uses mixtures of host tree compounds and the pheromone component frontalin to mass attack healthy trees. We found that exo-brevicomin was produced by both female and male D. valens, and that this pheromone functioned as an antiaggregating signal. Moreover, beetles feeding in pairs or in masses were more likely than were beetles feeding alone to produce exo-brevicomin, suggesting a potential role of sound by neighboring beetles in stimulating exo-brevicomin production. Sound playback showed that an agreement sound was produced by both sexes when exposed to the aggregation pheromone frontalin and attracts males, and an aggressive sound was produced only by males behaving territorially. These signals triggered the release of exo-brevicomin by both females and males, indicating an interplay of chemical and sonic communication. This study demonstrates that the bark beetle D. valens uses sounds to regulate the production of an antiaggregation pheromone, which may provide new approaches to pest management of this invasive species.

Physical contact, volatiles, and acoustic signals contribute to monogamy in an invasive aggregating bark beetle

“…First, it supports that mass trapping could potentially be a valid approach to decrease population density by increasing the difficulty of mate finding, especially by imposing Allee effects at low densities (Tobin et al, 2011). Second, combined with our studies, Liu et al (2013) and Liu et al (2017a) have establishment that frontalin functions as an aggregation pheromone and exobrevicomin functions as anti-aggregation pheromone, which supports the potential application of the push-pull strategy for protecting pine trees in North America (Cook et al, 2007). Third, various acoustic sounds were shown to attract or repel males, and manipulation of such signals may have potential to reduce beetle success in high-value trees (Hofstetter et al, 2013).…”

Design of a candidate vibrational signal for mating disruption against the glassy‐winged sharpshooter, Homalodisca vitripennis

“…For example, one approach to interfere with mate location behaviors could be artificial transmission of female vibrational signals that attract males to a trap (i.e., attract and kill) (Mazzoni et al ., unpublished). Another approach is the use of vibrational signals to induce release of alarm pheromones, which elicit dispersal behavior in individuals on the host plant (i.e., repellency) . The vibrational mating disruption method is based on the concept that transmission of a disruptive signal (DS) prevents or alters signal perception by the receiver located on the treated substrate.…”

“…1,2 For species that communicate or obtain information through substrate-borne vibrational signals, the application of mechanical principles that result in little to no negative environmental impact may constitute a valuable alternative and/or complement to pesticide applications. 3,4 Current approaches to exploiting vibrational signals include techniques to prevent insect pests from colonizing host plants, 5 mass trapping (Mazzoni et al, unpublished), and mating disruption 6 -8 to reduce population densities. The choice of approach depends on detailed knowledge of the composition of landscape vibrational signals, noise associated with the target species, and vibrations that elicit specific insect behavioral responses.…”

“…Another approach is the use of vibrational signals to induce release of alarm pheromones, which elicit dispersal behavior in individuals on the host plant (i.e., repellency). 5 The vibrational mating disruption method is based on the concept that transmission of a disruptive signal (DS) prevents or alters signal perception by the receiver located on the treated substrate. One approach is to over-power the frequency range of natural vibrational signals with emission of broadband signals (e.g., white noise) of an amplitude equal to or greater than natural pest signals.…”

Epibiotic Fungal Communities of Three Tomicus spp. Infesting Pines in Southwestern China

“…Most bark beetle species infest Pinus spp. [15,16], with several of these beetles being regarded as secondary intruders that colonize dead, diseased, or weakened trees [17,18]; however, a few beetles, such as those of Dendroctonus valens LeConte, Ips typographus Linnaeus, Scolytus multistriatus Marsham, and Tomicus yunnanensis Kirkendall and Faccoli, can colonize and kill healthy hosts [19,20]. Tomicus spp., which are among the most destructive beetles, can kill large numbers of healthy trees during periodic outbreaks [21,22].…”