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

Abstract

Animal communication systems are often exploited by eavesdropping antagonists, especially predators and ectoparasites. Female frog‐biting midges (Diptera: Corethrellidae) are known to use male anuran advertisement calls to locate their blood hosts, frogs. Here, we use acoustic midge traps broadcasting synthetic and recorded calls to identify those frog call parameters that affect midge attraction. At our study site in Pacific lowland Costa Rica, we found that overall midge attraction was influenced by both spectral and temporal acoustic parameters. Low dominant frequencies (below 1 kHz) and short pulse durations (between 125 and 500 ms) attracted the highest numbers of midges in tests with synthetic sinusoidal pure tones. These preferences partially explained the relative attractiveness of the advertisement calls of ten local frog species. The advertisement calls of the common and widespread Giant Bullfrog, Leptodactylus savagei (Anura: Leptodactylidae), attracted by far the largest number of midges, suggesting that this frog species might be a key resource for frog‐biting midges in Costa Rica. Although we found that calls of different frog species attracted different midge species/morphospecies in statistically different proportions, acoustic niche differentiation among midge species appeared to be moderate, suggesting either a limited degree of host specialization or the use of additional short‐range, that is, chemical, host recognition cues.

Within host acoustic signal preference of frog‐biting mosquitoes (Diptera: Culicidae) and midges (Diptera: Corethrellidae) on Iriomote Island, Japan

“…2019; Virgo et al . 2019). A similar pattern in preference among the calls of different host species has also been shown with frog‐biting mosquitoes in Japan (Toma et al .…”

“…2019; Leptodactylus savage : Virgo et al . 2019). These studies, however, relied on inter‐species variation in call structure.…”

“…Behavioral studies suggest that at least some species of frog‐biting mosquitoes and midges have generalized acoustic templates that allow them to detect and localize the calls of multiple anuran host species (Virgo et al . 2019; Toma et al . 2019; but see de Silva et al .…”

More than meets the eye: decrypting diversity reveals hidden interaction specificity between frogs and frog‐biting midges

“…Female frog‐biting midges (Diptera: Corethrellidae) eavesdrop on the nocturnal mating calls of their blood hosts, male frogs, being attracted by a combination of spectral and temporal call properties (Meuche et al ., 2016; Toma et al ., 2019; Virgo et al ., 2019). Costs imposed by frog‐biting midges on blood hosts could be substantial, ranging from irritation (indicated by defensive behaviours) and loss of blood (possibly substantial, see Camp, 2006) to an increased risk of infection with pathogens (Johnson et al ., 1993; Meuche et al ., 2016).…”

“…Like other blood feeders from the suborder Nematocera, frog‐biting midges are best regarded as micropredators rather than true parasites although the number of blood hosts per individual midge is certainly low, and presumably often one (the host). Calls of different species of frogs (McKeever & French, 1991; Grafe et al ., 2008; Virgo et al ., 2019), and also calls of different complexity of the same species (Bernal et al ., 2006; Aihara et al ., 2016), have been shown to attract variable numbers of midges. A study conducted by Grafe et al ., 2019 used bipartite interaction networks to analyse midge‐frog associations at different sites in Brunei Darussalam, showing strong differences in specialisation between two research sites.…”