Pan Traps as an efficient and low cost method for sampling Corethrella Coquillet, 1902 (Diptera: Corethrellidae)

Abstract

The genus Corethrella Coquillet, 1902 are known as a group of nocturnal frog-biting-midges (Diptera: Corethrellidae) which locate their frog-hosts through the sound emitted by their conspicuous calls. The classical method to capture these midges consists in using modified Center Disease Control (CDC) traps in which speakers emitting frog calls replace the light bulb. However, the high cost, volume and weight of CDC traps hampers several studies in remote areas and in countries with low research investments. Therefore, the main objective of this study was to compare the capture rate of the classic modified CDC trap with a new trap recently developed, here referred as PTM. We conducted an experiment at flooded areas in the vicinity of a lake in Florianópolis, Santa Catarina State, southern Brazil in which we arranged PTM and modified CDC traps emitting frog calls of two species commonly found in the area, Physalaemus nanus (Boulenger, 1888) and P. cuvieri Fitzinger, 1826. In a total of 34,5h sampling hours per trap (one trial per night for five days), the PTM traps captured over 20 times more individuals than modified CDC traps (n= 1594; n=72, respectively) and the same number of species (3). Those results demonstrate that the PTM method had a higher capture rate, are more practical and has a lower cost than modified CDC traps. We suggest further studies to investigate which aspects could explain the differences between capture rates among PTM, BG sentinel, bottle and CDC modified methods.