Necrophilous Insect Attraction to Cadaveric Volatile Organic Compounds

Abstract

Though it is well established that insects are attracted to decomposing vertebrates, little is known about the mechanism of attraction. Olfaction is thought to be the primary sense involved in resource location by necrophilous insects, and several studies have attempted to identify cadaveric-produced volatile organic compounds (VOCs) that contribute to insect attraction. This previous research has been completed almost exclusively in lab settings, with no field studies to verify these findings. The goal of my thesis was to test necrophilous insect attraction to nine cadaveric VOCs (1-butanol, 1-pentanol, p­-xylene, o-xylene, ethanol, cyclohexanone, acetamide, dimethyl disulfide, and dimethyl trisulfide) in a field setting. Pitfall traps at six research locations were baited with the chemicals for one week. Specimens collected from the traps were identified and species assemblages were compared to those of a pig carcass. Replicates were conducted in fall 2018 and spring 2019. Two chemicals were identified as important attractants for a variety of necrophilous insects: dimethyl disulfide and dimethyl trisulfide. These chemicals were especially attractive to Phormia regina, a blow fly (Diptera: Calliphoridae) found worldwide. VOC insect communities did not include all of the insects found on carcasses, possibly indicating the necessity of chemical blends for effective attraction. This study is only the second study to test necrophilous insect attraction in a field setting.