Ephemeral resources are excellent environments in which to study the dynamics of resource partitioning within insect communities. Among the many groups of organisms that exploit decomposing substrates, such as dung and carrion, is the beetle family Scarabaeidae. Among this diverse group are multiple guilds, which partition temporary resources in time and space. This study investigated how selected scarab species partition resources in time, and to determine the volatile chemical profile of these resources throughout decomposition.
The response of two species, Ateuchus histeroides and Geotrupes splendidus, to decomposing dung, carrion, and fungi was tested in a controlled environment. Beetles were allotted 10 minutes to respond to a single resource in a wind tunnel. Each resource was tested at 24-hour intervals of decay from 0 to 168 hours. Ordinal logistic regression showed that A. histeroides responded significantly to fresh dung, and G. splendidus responded to all resources with little discrimination among decay stages. These results suggest that A. histeroides assumes a more specialized feeding strategy, whereas the strategy of G. splendidus is more opportunistic.
The volatile chemical profiles of decaying dung, carrion, and fungi were determined by gas chromatography-mass spectrometry. Results indicated multiple compounds among each resource, with ten of those compounds shared between resources. There also were compounds specific to fresh dung, not present in proceeding decay stages. These results could suggest potential attractive compounds to which A. histeroides and G. splendidus are responding, and generate hypotheses for determining the appropriate chemical blend that would elicit a natural response.
Species 1: Coleoptera Scarabaeidae Ateuchus histeroides (dung beetle)
Species 2: Coleoptera Scarabaeidae Geotrupes splendidus
Keywords: gas chromatography-mass spectrometry, wind tunnel
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