Antiparasitic Properties of Cantharidin and the Blister Beetle Berberomeloe majalis (Coleoptera: Meloidae)

Abstract

Cantharidin (CTD) is a toxic monoterpene produced by blister beetles (Fam. Meloidae) as a chemical defense against predators. Although CTD is highly poisonous to many predator species, some have evolved the ability to feed on poisonous Meloidae, or otherwise beneficially use blister beetles. Great Bustards, <i>Otis tarda</i>, eat CTD-containing <i>Berberomeloe majalis</i> blister beetles, and it has been hypothesized that beetle consumption by these birds reduces parasite load (a case of self-medication). We examined this hypothesis by testing diverse organisms against CTD and extracts of <i>B. majalis</i> hemolymph and bodies. Our results show that all three preparations (CTD and extracts of <i>B. majalis</i>) were toxic to a protozoan (<i>Trichomonas vaginalis</i>), a nematode (<i>Meloidogyne javanica</i>), two insects (<i>Myzus persicae</i> and <i>Rhopalosiphum padi</i>) and a tick (<i>Hyalomma lusitanicum</i>). This not only supports the anti-parasitic hypothesis for beetle consumption, but suggests potential new roles for CTD, under certain conditions.