Response of adult carrion beetles Necrodes littoralis (L.) (Staphylinidae: Silphinae) to selected cadaveric volatile organic compounds: laboratory and field tests

Carrion insects need to quickly and accurately locate a suitable carcass to maximize their reproductive success. They are attracted by cadaveric volatile organic compounds (VOCs). However, very little is known about VOCs that attract insects at later stages of carrion decomposition. Here, we tested the response of Necrodes littoralis (Linnaeus, 1758). (Staphylinidae: Silphinae), a Palearctic beetle that colonizes large carrion late in decomposition, to selected VOCs. First, in the laboratory choice tests we demonstrated that the beetles reveal no preference for meat with larval blow flies over meat alone. This finding indicates that both, the fly larvae and the feeding matrix they form on meat are not the source of specific attractants for the adult beetles of Necrodes Leach, 1815. Therefore, we focused on VOCs that are related to carrion putrefaction. We tested the response of the beetles to benzyl butyrate, butan-1-ol, butyric acid, cadaverine, dimethyl disulfide (DMDS), dimethyl trisulfide, indole, phenol, putrescine and skatole in laboratory choice assays and field trapping tests. None of the compounds elicited the positive and significant response of the beetles under laboratory or field conditions, indicating that these VOCs are probably not the attractants of N. littoralis. Moreover, in the field tests we found a significant attraction of Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) to traps with DMDS. DMDS revealed also a positive (however insignificant) response of Saprinus spp. (Coleoptera: Histeridae) and Sarcophaga spp. (Diptera: Sarcophagidae). Sarcophaga flies were also attracted to traps with butyric acid. These findings expand the knowledge on chemoecology of carrion insects, highlighting the need to further search for VOCs that attract late-colonizers of carrion.