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Studies on the consequences of urbanization often examine the effects of light, noise, and heat pollution independently on isolated species providing a limited understanding of how these combined stressors affect species interactions. Here, we investigate how these factors interact to affect parasitic frog-biting midges (Corethrella spp.) and their túngara frog (Engystomops pustulosus) hosts. A survey of túngara frog calling sites revealed that frog abundance was not significantly correlated with urbanization, light, noise, or temperature. In contrast, frog-biting midges were sensitive to light pollution and noise pollution. Increased light intensity significantly reduced midge abundance at low noise levels. At high noise intensity, there were no midges regardless of light level. Two field experiments controlling light and noise levels to examine attraction of the midges to their host and their feeding behavior confirmed the causality of these field patterns. These findings demonstrate that both light and noise pollution disrupt this host–parasite interaction and highlight the importance of considering interactions among species and types of pollutants to accurately assess the impacts of urbanization on ecological communities.

A new species of frog-biting midge in the genus Corethrella Coquillett from Death Valley National Park, California, United States of America, is described, based on a single female. The species belongs to the rotunda species group, which are otherwise known to have hyporheic larvae. The species is placed phylogenetically within the group, and a modified portion of a Nearctic key is presented. The rotunda species group now contains 13 species, three of which are in the Nearctic, and the remaining 10 of which are in the Neotropical region.

This study investigated frog‐biting dipteran species using newly designed frog‐calling traps in Taiwan. The trap effectively collected specimens from both families, Culicidae and Corethrellidae, demonstrating its utility. Host preference analysis revealed that Odorrana swinhoana (Boulenger, 1903) and Kurixalus eiffingeri (Boettger, 1895) were most frequently associated with collected specimens of Corethrellidae. Additionally, the corethrellids were predominantly attracted to a sound frequency around 2200 to 2700 Hz. Then, DNA barcoding was also conducted on the four collected species of Culicidae: Armigeres subalbatus (Coquillett, 1898), Uranotaenia nivipleura Leicester, 1908, Ur . macferlanei Edwards, 1914, and Mimomyia luzonensis (Ludlow, 1905), and the mitochondrial genome of Corethrella nippon Miyagi 1980 was first sequenced and annotated. Mitogenome‐based phylogenetic analysis confirmed that C. nippon formed a clade with Corethrella condita Borkent, 2008. In our analysis, family Corethrellidae clustered with Culicidae; however, the inter‐family phylogenetic relationships within Culicoidea appeared paraphyletic, particularly concerning family Chaoboridae. Future studies should explore a greater variety of frog species across more diverse regions and use other genomic datasets beyond the mitogenome to infer a more robust deep topology at the superfamily level and further broaden our understanding of host preference.

Background Female frog-biting midges ( Corethrella ) are hematophagous micropredators that feed on frogs and serve as vectors for trypanosomes ( Trypanosoma ), unicellular flagellate parasites. Little is known about the infection ecology and host specialization within this tritrophic interaction. Methods In this study, we explore the prevalence, diversity and specificity of Trypanosoma infections in Corethrella across various localities in tropical America and Borneo by sequencing both midge and trypanosome markers in midge samples. Results Bayesian phylogenetic analyses and ASAP species delimitation of Corethrella (cytochrome c oxidase I [COI]) and Trypanosoma (18S, glyceraldehyde 3-phosphate dehydrogenase [GAPDH]) revealed a previously unknown high diversity of frog-biting midge-associated trypanosomes. Across regions and localities, the infection prevalence in midges caught by acoustic midge traps ranged from 2.9% to 23.5%, suggesting that a notable proportion of midges carried trypanosomes, likely acquired from a previous blood meal. At one locality, La Gamba (Costa Rica), the infection prevalence in trap-caught midges was 10.9%, while it was even higher in midges collected directly from frog hosts (20.7%), in agreement with the hypothesis that midges ingest trypanosomes from infected frogs. Bipartite network analyses revealed high degrees of specialization of Trypanosoma in trap-caught Corethrella, both across all localities (H2′ = 0.87) and when analyzed for our most sampled locality (Cahuita, Costa Rica) alone (H2′ = 0.94). Conclusions Our data suggest that most trypanosomes detected in trap-caught midges are established, host-competent (i.e., specialist) parasites in an infective stadium. Graphical Abstract

It is well known that female adults of frog-biting midges (Corethrellidae) are attracted by anuran mating calls. However, the role of host-emitted cues other than mating calls in determining the level of attraction remains poorly understood. Here, we performed field playback experiments to test how the host-seeking behaviour of Corethrella Coquillett is influenced by different sound stimuli: mating call of a tree frog, cricket call, and no sound. Then, after long-distance host detection, we evaluated if Corethrella can distinguish landing sites by using at short distance the colour and/or shape of anurans. For that, we placed artificial models of frogs with different colours (light green and dark brown) and an artificial caterpillar model (light green colour) on the top of speakers. We found that only frog mating calls presented with the visual cue of an artificial frog were attacked by Corethrella , suggesting that frog shape, regardless of colour, is an important cue for the identification of its hosts. This is the first study providing evidence that after flying long distances guided by frog calls, Corethrella can identify their hosts using visual cues at short distances.

Although males often display from mixed-species aggregations, the influence of nearby heterospecifics on risks associated with sexual signalling has not been previously examined. We tested whether predation and parasitism risks depend on proximity to heterospecific signallers. Using field playback experiments with calls of two species that often display from the same ponds, túngara frogs and hourglass treefrogs, we tested two hypotheses: (1) calling near heterospecific signallers attractive to eavesdroppers results in increased attention from predatory bats and parasitic midges (collateral damage hypothesis) or (2) calling near heterospecific signallers reduces an individual's predation and parasitism risks, as eavesdroppers are drawn to the heterospecifics (shadow of safety hypothesis). Bat visitation was not affected by calling neighbours. The number of frog-biting midges attracted to hourglass treefrog calls, however, rose threefold when played near túngara calls, supporting the collateral damage hypothesis. We thus show that proximity to heterospecific signallers can drastically alter both the absolute risks of signalling and the relative strengths of pressures from predation and parasitism. Through these mechanisms, interactions between heterospecific guild members are likely to influence the evolution of signalling strategies and the distribution of species at both local and larger scales.

Hematophagous arthropods often choose predictable feeding sites on their hosts´ body, presumably to maximize blood uptake while minimizing costs. Feeding sites can be host-specific, mediated by intrinsic host characters and/or specific preferences of the blood feeder. We investigated feeding site specificity in a community of frog-biting midges (Corethrella spp.) and frog hosts in La Gamba, Costa Rica. Midge distribution on hosts differed significantly between 12 investigated frog species, indicating that intrinsic host properties influence potential feeding sites. However, realized feeding sites were also significantly different between four investigated Corethrella morphotypes, across all hosts but also within certain shared hosts, indicating feeding site partitioning among Corethrella. We propose that the diversity of feeding sites in Corethrella-frog associations is determined by an interaction of host traits, e. g. calling site, defensive behavior or skin thickness, and midge traits, especially body size and corresponding mouthpart size/structure.

Native predators are postulated to have an important role in biotic resistance of communities to invasion and community resilience. Effects of predators can be complex, and mechanisms by which predators affect invasion success and impact are understood for only a few well-studied communities. We tested experimentally whether a native predator limits an invasive species' success and impact on a native competitor for a community of aquatic insect larvae in water-filled containers. The native mosquito Aedes triseriatus alone had no significant effect on abundance of the invasive mosquito Aedes albopictus. The native predatory midge Corethrella appendiculata, at low or high density, significantly reduced A. albopictus abundance. This effect was not caused by trait-mediated oviposition avoidance of containers with predators, but instead was a density-mediated effect caused by predator-induced mortality. The presence of this predator significantly reduced survivorship of the native species, but high predator density also significantly increased development rate of the native species when the invader was present, consistent with predator-mediated release from interspecific competition with the invader. Thus, a native predator can indirectly benefit its native prey when a superior competitor invades. This shows the importance of native predators as a component of biodiversity for both biotic resistance to invasion and resilience of a community perturbed by successful invasion.

Females of frog-biting midges (Corethrellidae) obtain their blood meals from male calling frogs. While the morphology of the feeding apparatus is well studied in hematophagous Diptera that impact humans, frog-biting midges have received far less attention. We provide a detailed micromorphological examination of the piercing blood-sucking proboscis and maxillary palpus in three Corethrella species using scanning electron microscopy and histological semi-thin sectioning. We also compare the sensilla found on the proboscis tip and the palpus of Corethrella with other piercing blood-sucking Diptera. Corethrella spp. have a proboscis length of about 135 µm, equipped with delicate mandibular piercing structures composing the food canal together with the labrum and hypopharynx. Their proboscis composition is plesiomorphic and more similar to other short-proboscid hematophagous Culicomorpha (e.g., Simuliidae), in contrast to the phylogenetically more closely related long-proboscid Culicidae. As in other short-proboscid taxa, the salivary canal in Corethrella spp. transitions into an open salivary groove with one mandible forming a seal, whereas in Culicidae the salivary canal is closed until the tip of the proboscis. We discuss the possible functional constraints of very short, piercing blood-sucking proboscises (e.g., dimensions of host blood cells) that may limit the size of the food canal.

Corethrellaoppositophila Kvifte & Bernal, sp. n. is described based on one male and six female specimens collected at 2200 m a.s.l. on Mount Wilhelm, Papua New Guinea. The species is the fourth species of frog-biting midge described from this country and appears similar to Corethrellasolomonis Belkin based on pigmentation of legs and abdominal tergites. It differs from C.solomonis , however, in the shape of female flagellomeres I–III, and in the thorax which has a dark brown vertical stripe. The new species is named for its sexually dimorphic flagellomeres, which are short and squat in the female and elongate in the male. These differences in morphological characters are discussed in light of the likely sexual differences in functional uses of the antennae, as males use them for mating only whereas females use them both for mating and prey location. An emended key is presented to the described Australopapuan species of Corethrellidae.