Quinone mixture as attractant for necrophagous dung beetles specialized on dead millipedes.

2-Methyl-1,4-benzoquinone (toluquinone) and 2-methoxy-3-methyl-1,4-benzoquinone are the most common components of defensive secretions of juliform millipedes (Diplopoda: Juliformia). A natural and a synthetic millipede-defensive secretion composed of these two substances attract dung beetles of a few Onthophagus species (Coleoptera: Scarabaeidae) that feed mainly on freshly dead millipedes. This olfactory mechanism and adaptation to the toxic effects of quinones enables them to be the first and exclusive users of this resource.