One Hundred Million Years of Chemical Warfare by Insects

An important defensive strategy among animals is the use of chemical compounds with toxic or irritating properties. In this paper, we report the discovery of an Early Cretaceous soldier beetle (Coleoptera: Cantharidae) in Burmese amber that seemingly employed a chemical defense response against a potential predator. Six pairs of cuticular vesicles with associated gland reservoirs were extruded from the insect’s abdomen, and a secretion released from one of these covers a portion of the antenna of a second insect species, considered to be the perpetrator of the response. This is the earliest fossil record of a putative chemical defense response and suggests that chemical defense mechanisms in beetles have been in existence for at least 100 Ma.