Sound production in bark and ambrosia beetles

Abstract

Bark and ambrosia beetles and pinhole borers (Coleoptera: Curculionidae: Scolytinae and Platypodinae) are two subfamilies of weevils that use acoustic communication within plant tissue. These insects transmit and detect sound in a medium that is neither air nor water and they are among the smallest animals with sound-producing organs. Nevertheless, their sound production is sorely understudied, mostly due to the difficulties associated with acoustically monitoring individuals inside plants. We analysed the stridulatory sounds from 55 bark and ambrosia beetle species within 15 subtribes collected in four countries, making this the largest acoustic dataset of these taxa to date. We characterized and compared the amplitude and spectro-temporal parameters of the distress airborne signals produced by the beetles, in conjunction with phenology and life history data. Sound production was present in 33% of the collected species, of which 60% of these sounds had not been previously reported. Depending on species, either both sexes stridulated or only one. Some species had calls with different acoustic morphotypes (one, two, or three notes), and when both sexes stridulated, sounds generally differed. Our data suggest that type of mating system and size play an important role in determining the acoustic communicatory capacity of most species.

Survival Sounds in Insects: Diversity, Function, and Evolution

“…Cases where only one sex produces both sexual and defense sounds may also indicate that the sonic defenses evolved from a pre-existing sexual signal. For instance, many species of bark beetles show sexual dimorphism in sound production whereby only one sex produces sounds in both sexual and defensive contexts (Bedoya et al, 2019). In cicadas, Smith and Langley (1978) proposed that disturbance squawks evolved secondarily to courtship sounds as both sound types, when produced via tymbals, are found only in males.…”

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

“…Distressed sounds produced by Ips confusus adults were recorded and elicited by gently holding the beetle by the abdomen with soft forceps (featherweight forceps #4748, BioQuip) to allow for full range of movement of the vertex-pronotal structures. Of the bark beetles that produce sounds, most stridulate in response to disturbance such as Recordings of 17 female beetles were automatically analyzed using feature extraction methods developed in MatLab R2018b [12]. Spectrograms were produced using the following parameters: Hamming window with a 1024 sample size, 1024 frequency bins, and 75% overlap (768 samples) (Figure 3).…”

“…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]. Interestingly, 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]. Airborne sounds and stridulatory structures of many bark beetles have been described [13,[15][16][17][18][19] and the ecological roles of stridulation in some bark beetle species are well studied [18,[20][21][22][23][24][25][26][27].…”

“…Acoustic communication is present in at least half of the subtribes of the Scolytinae, and stridulatory structures of bark beetles have evolved multiple times [52]. Three primary stridulatory mechanisms within bark beetles (Scolytinae) are known: elytro-tergal, vertex-pronotal, and gula-prosternal stridulatory organs [11,12,45]. Stridulatory structures of Ips confusus have been described by Barr [11] but the stridulation sounds produced by female I. confusus have not been analyzed or illustrated [12].…”

“…Three primary stridulatory mechanisms within bark beetles (Scolytinae) are known: elytro-tergal, vertex-pronotal, and gula-prosternal stridulatory organs [11,12,45]. Stridulatory structures of Ips confusus have been described by Barr [11] but the stridulation sounds produced by female I. confusus have not been analyzed or illustrated [12]. Ips confusus' stridulatory structure is categorized as vertex-pronotal type [11].…”