Evaluation of the diet of a carabid predator using fluorescent marking of prey

Abstract

Abstract. We present a UV-fluorescent dye-based prey marking technique, using three different dyes, with later detection of the dyes in the guts of predators using a micro-plate fluorescent reader. By using this new method of detecting dyes based on their different excitation and emission characteristics it is possible to simultaneously screen 96 samples for multiple fluorescent-markers in less than 30 minutes. The marking is stable, cheap, non-toxic and had no effect on the choice of the carabid predator Pterostichus melanarius between marked and unmarked fly larvae (Musca domestica). Different fluorescent dyes provide variable detection intervals up to 100% detectability at 96 h post-ingestion by this predator. The simple marking, extraction and detection methods presented could be used in food web research to map individual trophic links and predator preference for different types of prey.