A chorus for a feast

Abstract

Frog-biting midges (Corethrella sp) and culicid mosquitoes were observed feeding on a hylid frog (Boana caiapo; top) in northern Mato Grosso, Brazil. Although in popular folklore flies and their relatives are commonly preyed upon by frogs and toads, several dipterans – including corethrellid midges – are specialized anuran parasites. The female midges track frog calls to locate potential hosts, from which they feed and ingest a blood meal (note the blood-filled abdomens of some individuals surrounding the frog’s eyes and nostrils). Corethrellid midges may also transmit trypanosomes (parasitic protozoa) to anurans, and variations in midge abundance caused by environmental changes warrant further research, as they may have important consequences for amphibian conservation. Phonotaxis (movement cued by sound) practiced by midges is directly related to the prevalence of bites on anterior portions of frogs, whereas the more generalist culicid mosquitoes, which are attracted to their hosts by CO2, often bite opportunistically over a frog’s body. Circular pale marks commonly observed on frogs of the Boana geographica species group (such as these on what resembles B semilineata but may be another Boana species; bottom) are typically caused by mosquito bites. The broader ecological implications of relationships between anurans and dipterans remain largely unknown.