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Most mosquito and midge species use hearing during acoustic mating behaviors. For frog-biting species, however, hearing plays an important role beyond mating as females rely on anuran calls to obtain blood meals. Despite the extensive work examining hearing in mosquito species that use sound in mating contexts, our understanding of how mosquitoes hear frog calls is limited. Here, we directly investigated the mechanisms underlying detection of frog calls by a mosquito species specialized on eavesdropping on anuran mating signals: Uranotaenia lowii. Behavioral, biomechanical and neurophysiological analyses revealed that the antenna of this frog-biting species can detect frog calls by relying on neural and mechanical responses comparable to those of non-frog-biting species. Our findings show that in Ur. lowii, contrary to most species, males do not use sound for mating, but females use hearing to locate their anuran host. We also show that the response of the antennae of this frog-biting species resembles that of the antenna of species that use hearing for mating. Finally, we discuss our data considering how mosquitoes may have evolved the ability to tap into the communication system of frogs.

 

Individuals from multiple species often aggregate at resources, group to facilitate defense and foraging, or are brought together by human activity. While it is well-documented that host-seeking disease vectors and parasites show biases in their responses to cues from different hosts, the influence of mixed-species assemblages on disease dynamics has received limited attention. Here, we synthesize relevant research in host-specific vector and parasite bias. To better understand how vector and parasite biases influence infection, we provide a conceptual framework describing cue-oriented vector and parasite host-seeking behaviour as a two-stage process that encompasses attraction of these enemies to the assemblage and their choice of hosts once at the assemblage. We illustrate this framework, developing a case study of mixed-species frog assemblages, where frog-biting midges transmit trypanosomes. Finally, we present a mathematical model that investigates how host species composition and asymmetries in vector attraction modulate transmission dynamics in mixed-species assemblages. We argue that differential attraction of vectors by hosts can have important consequences for disease transmission within mixed-species assemblages, with implications for wildlife conservation and zoonotic disease. 

Predators and parasites are critical, interconnected members of the community and have the potential to shape host populations. Predators, in particular, can have direct and indirect impacts on disease dynamics. By removing hosts and their parasites, predators alter both host and parasite populations and ultimately shape disease transmission. Selective predation of infected hosts has received considerable attention as it is recognized to have important ecological implications. The occurrence and consequences of preferential consumption of uninfected hosts, however, has rarely been considered. Here, we synthesize current evidence suggesting this strategy of selectively predating uninfected individuals is likely more common than previously anticipated and address how including this predation strategy can change our understanding of the ecology and evolution of disease dynamics. Selective predation strategies are expected to differentially impact ecological dynamics and therefore, consideration of both strategies is required to fully understand the impact of predation on prey and host densities. In addition, given that different strategies of prey selectivity by predators change the fitness payoffs both for hosts and their parasites, we predict amplified coevolutionary rates under selective predation of infected hosts compared to uninfected hosts. Using recent work highlighting the critical role that predators play in disease dynamics, we provide insights into the potential mechanisms by which selective predation on healthy individuals can directly affect ecological outcomes and impact long‐term host–parasite coevolution. We contrast the consequences of both scenarios of selective predation while identifying current gaps in the literature and future research directions. 

Eavesdropping predators, parasites and parasitoids exploit signals emitted by their prey and hosts for detection, assessment, localization and attack, and in the process impose strong selective pressures on the communication systems of the organisms they exploit. Signallers have evolved numerous anti‐eavesdropper strategies to mitigate the trade‐off between the costs imposed from signal exploitation and the need for conspecific communication. Eavesdropper strategies fall along a continuum from opportunistic to highly specialized, and the tightness of the eavesdropper–signaller relationship results in differential pressures on communication systems. A wide variety of anti‐eavesdropper strategies mitigate the trade‐off between eavesdropper exploitation and conspecific communication. Antagonistic selection from eavesdroppers can result in diverse outcomes including modulation of signalling displays, signal structure, and evolutionary loss or gain of a signal from a population. These strategies often result in reduced signal conspicuousness and in decreased signal ornamentation. Eavesdropping enemies, however, can also promote signal ornamentation. While less common, this alternative outcome offers a unique opportunity to dissect the factors that may lead to different evolutionary pathways. In addition, contrary to traditional assumptions, no sensory modality is completely ‘safe’ as eavesdroppers are ubiquitous and have a broad array of sensory filters that allow opportunity for signal exploitation. We discuss how anthropogenic change affects interactions between eavesdropping enemies and their victims as it rapidly modifies signalling environments and community composition. Drawing on diverse research from a range of taxa and sensory modalities, we synthesize current knowledge on anti‐eavesdropper strategies, discuss challenges in this field and highlight fruitful new directions for future research. Ultimately, this review offers a conceptual framework to understand the diverse strategies used by signallers to communicate under the pressure imposed by their eavesdropping enemies.

 

Haematophagous insects can rely on specialized host‐seeking behaviors to locate hosts. Some frog‐biting flies, for example, eavesdrop on the conspicuous acoustic signals produced by male frogs and toads. Using such auditory cues to locate a host imposes an additional challenge: how to recognize appropriate sounds when different frog species produce calls with varying acoustic properties. The limited knowledge of antennal hearing in dipteran insects hinders our ability to understand how eavesdropping flies detect and recognize frog calls. Behavioral studies suggest that frog‐biting flies use broad acoustic templates to detect and recognize their victims. Here, we use within‐species call variation to examine the acoustic preferences in frog‐biting flies. Specifically, we examine the attraction of frog‐biting mosquitoes (Uranotaeniaspp.) and midges (Corethrella nippon) to the calls of a Japanese treefrog, the Ryukyu Kajika frog (Buergeria japonica), on Iriomote Island, Japan. Male Ryukyu Kajika frogs produce two call types. While both calls have a high frequency peak (3 kHz), the first call type (Type I) also contains a lower frequency peak (1.8 kHz) absent in the second call type (Type II). Using field phonotaxis experiments we found that Type I calls are more attractive to both frog‐biting mosquitoes and midges. Thus, our results suggest that the frog‐biting Nematoceran flies in this community are biased towards the acoustic properties of Type I calls. We discuss this finding in the context of the evolution of antennal hearing in flies.

 

In the evolutionary arms race between predators and their prey, prey often evolve to be as cryptic as they can, while predators in turn hone their sensory strategies to detect prey. Examinations of the sensory strategies implemented by predators to detect their prey, as well as the ecological consequences of these interactions, are at the crux of understanding and predicting predator–prey dynamics.

We review the sensory strategies used by predators that rely on private information (attending directly to cues and signals generated by their prey) and those that gather social information (attending to the signals and behaviours of others). We focus our enquiry on bats, an ideal group to shed light on these questions given their ecological diversity, varied foraging strategies and wide range of social behaviours.

We discuss the costs and benefits of using private and social information for foraging. We investigate diverse strategies of information use and examine the effects different predatory strategies have on predator sensory systems.

We provide an overview of the sensory ecology of information use in hunting in bats and, by identifying current gaps in knowledge, highlight fruitful directions for future research.

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