Acoustic Preference of Frog‐Biting Midges (Corethrella spp) Attacking Túngara Frogs in their Natural Habitat

Abstract

In many animals, males aggregate to produce mating signals that attract conspecific females. These leks, however, also attract eavesdropping predators and parasites lured by the mating signal. This study investigates the acoustic preferences of eavesdroppers attracted to natural choruses in a Neotropical frog, the t ungara frog (Engystomops pustulosus). In particular, we examined the responses of frog-biting midges to natural variation in call properties and signaling rates of males in the chorus. These midges use the mating calls of the frogs to localize them and obtain a blood meal. Although it is known that the midges prefer complex over simple t ungara frog calls, it is unclear how these eavesdroppers respond to natural call variation when confronted with multiple males in a chorus. We investigated the acoustic preference of the midges using calling frogs in their natural environment and thus accounted for natural variation in their call properties. We performed field recordings using a sound imaging system to quantify the temporal call properties of males in small choruses. During these recordings, we also collected frog-biting midges attacking calling males. Our results revealed that, in a given chorus, male frogs calling at higher rates and with higher call complexity attracted a larger number of frog-biting midges. Call rate was particularly important at increasing the number of midges attracted when males produced calls of lower complexity. Similarly, call complexity increased attractiveness to the midges especially when males produced calls at a low repetition rate. Given that female t ungara frogs prefer calls produced at higher repetition rates and higher complexity, this study highlights the challenge faced by signalers when increasing attractiveness of the signal to their intended receivers.

The sound of a blood meal: Acoustic ecology of frog‐biting midges (Corethrella) in lowland Pacific Costa Rica

“…Notably, all calls that were efficient (i.e., consistently showing high catch numbers) in attracting midges were found in either the most efficient range of peak frequencies or pulse durations (250-500 ms) as revealed by artificial call models, with the most efficient calls (L. savagei, S. phaeota) matching both criteria. This indicates that both spectral (peak frequency) and temporal (single call duration) are important parameters in host finding, corroborating the findings of previous studies (Aihara, Silva, Bernal, & Wright, 2016;Bernal, Page, Rand, & Ryan, 2007;Meuche et al, 2016). However, it is likely that additional spectral parameters (e.g., fundamental frequency, harmonics) take effect during the midges' phonotaxis, indicated by the effectiveness of three of our test calls (D. ebraccatus, L. fragilis, S. boulengeri) that could not be explained by their peak frequencies but were presumably based on lower fundamental frequencies.…”

Developing a Phonotaxis Performance Index to Uncover Signal Selectivity in Walking Phonotaxis

“…(Fowler, 1987;Parkman et al, 1996), Ormia linefrons, Homotrixa alleni, and Therobia leonidei that parasitize various katydid species (Burk, 1982;Allen, 1995;Shapiro, 1995;Lehmann, 2003) and sarcophagids (i.e., Emblemasoma auditrix) that parasitize cicadas (Schniederkotter and Lakes-Harlan, 2004). The evolution of convergent signal preferences between some eavesdroppers and intended receivers (Wagner, 1996;Bernal, 2006;Aihara et al, 2016) suggests that they are solving similar sensory problems: detecting, recognizing, and localizing common communication signals. However, signalers and eavesdroppers likely accomplish these sensory processing tasks with different peripheral and central nervous systems.…”

Visualizing Phonotactic Behavior of Female Frogs in Darkness

“…To discriminate the frequency of the sound sources, we compared the illumination pattern of sound-indication devices with the spectrogram of the audio data recorded by the video camera according to the method proposed by Aihara et al . 19 . Figure 4a depicts the illumination patterns and spectrogram recorded during a playback experiment (corresponding to the experiment shown in Fig.…”