Purdue University

Bernal Lab

Sensory Ecology of Interspecific eavesdropping of mating signals

Antennae and putative earExploitation of sexual signals is a widespread strategy across predators and parasites from a variety of taxa. Yet, relatively little research has evaluated the behavioral strategies, sensory specializations or evolution of unintended receivers. With few exemptions, investigations of interspecific eavesdropping have focused on the signaler rather than on the unintended receiver. Though this research has shown the importance of eavesdropping on the communication system of the species being exploited, it has not determined the strategies and characteristics that allow evolutionary transitions to use another species’ communication system. Our work investigate the sensory ecology of eavesdroppers to ultimately understand the evolution of this behavior. We investigate a tractable and diverse system of interspecific eavesdroppers: frog-biting midges (Corethrella spp). This family contains 100+ species, most of which depend on frog’s blood to reproduce. Female midges use frog mating calls to locate frogs and obtain a blood meal.

Our efforts on this front are divided into two major components:

Neuroethology of eavesdropping in frog-biting midges: Early researchers suggested that the antennal sensilla pediconica could act as a sound receptor in frog-biting midges, but its role in hearing seems unlikely. The midges have setose antennae and large Johnston’s organs, and like mosquitoes, may use them to transduce sound-induced vibrations of the antennal flagellum. Responses to relatively high frequency sounds in the far field could mean that a more elaborate pressure-sensitive organ is involved in hearing. Examinations of the midges revealed a putative tympanic ear. Ongoing collaborations with Dr. Ron Hoy are further exploring the auditory system of frog-biting midges.

PhylogenyPhylogeny of frog-biting midges: A robust phylogeny is required for a comprehensive understanding of the evolution of traits associated with interspecific eavesdropping. We are working on developing a molecular phylogeny of frog-biting midges to further understand the relationships between species in this group and be able to evaluate hypothesis about trait evolution in this group.