Hematophagous Flies Attracted to Frog Calls in a Preserved Seasonal Forest of the Austral Neotropics, with a Description of a New Species of Corethrella (Diptera: Corethrellidae)

The exploitation of sexual signals by predators: a meta-analysis

Sexual signals are often central to reproduction, and their expression is thought to strike a balance between advertising to mates and avoiding detection by predatory eavesdroppers. Tests of the predicted predation costs have produced mixed results, however. Here we synthesized 187 effects from 78 experimental studies in a meta-analytic test of two questions; namely, whether predators, parasites and parasitoids express preferences for the sexual signals of prey, and whether sexual signals increase realized predation risk in the wild. We found that predators and parasitoids express strong and consistent preferences for signals in forced-choice contexts. We found a similarly strong overall increase in predation on sexual signallers in the wild, though here it was modality specific. Olfactory and acoustic signals increased the incidence of eavesdropping relative to visual signals, which experienced no greater risk than controls on average. Variation in outcome measures was universally high, suggesting that contexts in which sexual signalling may incur no cost, or even reduce the incidence of predation, are common. Our results reveal unexpected complexity in a central viability cost to sexual signalling, while also speaking to applied problems in invasion biology and pest management where signal exploitation holds promise for bio-inspired solutions.

Not only a listener: female frog-biting midges (Corethrellidae) also distinguish the shape of frogs

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.

A new species of frog-biting midge from Papua New Guinea with a key to the described Corethrellidae of the Australopapuan region (Diptera, Corethrellidae, Corethrella)

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.