A synergism between dimethyl trisulfide and methyl thiolacetate in attracting carrion-frequenting beetles demonstrated by use of a chemically-supplemented minimal trap

Volatile organic compounds derived from microbes recruit insects to carrion, shaping community assembly and ecological succession. The importance of individual volatiles and interactions between volatiles are difficult to assess in the field because of (1) the myriad compounds from decomposing animals and (2) the likelihood that complex volatile blends are important for the final approach to carrion. On the assumption that searching carrion-frequenting beetles may use simpler cues to orient at a distance, we employed a chemically-supplemented minimal trap that uses test chemicals associated with active decay to attract from a distance and a minimal carrion bait (a small fresh mouse carcass) to induce trap entry. Traps supplemented with both methyl thiolacetate (MeSAc) and dimethyl trisulfide (DMTS) attracted greater numbers of beetles including adult silphids (Necrophila americana and Oiceoptoma noveboracense) and the histerid Euspilotus assimilis than the combined totals of DMTS-only and MeSAc-only traps, demonstrating a synergism. The attraction of larval Necrophila americana to traps left in the field for less than 24?h suggests that larvae move between carrion sources. The use of such species for forensic applications requires caution.