Evolution: Soldier beetle self-defence

A defensive compound found within soldier beetles is produced by the animals’ genes and not obtained from their diet as was previously thought. The work published in Nature Communications this week suggests that the biosynthesis of this compound evolved independently of the biosynthetic routes in plants and fungi.

Soldier beetles are known to secrete the compound DHMA which has protective effects against infectious agents and potential predators. The family of acids, which includes DHMA, has highly potent biological activities and some compounds have even been investigated as human anti-cancer and anti-microbial treatments.

Soldier beetles have been observed to forage on flowers of certain plants that also contact DHMA and, as no other animals have been reported to contain the compound, it has been suggested that the presence of the compound in the insect may reflect this dietary link. Victoria Haritos and colleagues now identify genes in the beetles that produce the defensive compound. They expressed the genes in yeast and determined the activities of the proteins, allowing them to conclude that the compound is produced by a route distinct from that found in plants.