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

Whitman Whitman,González-Coloma González-Coloma,Olmeda Olmeda,Martínez-Díaz Martínez-Díaz,Andrés Andrés,Ibáñez-Escribano Ibáñez-Escribano

doi:10.3390/toxins11040234

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, Otis tarda, eat CTD-containing Berberomeloe majalis 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 B. majalis hemolymph and bodies. Our results show that all three preparations (CTD and extracts of B. majalis) were toxic to a protozoan (Trichomonas vaginalis), a nematode (Meloidogyne javanica), two insects (Myzus persicae and Rhopalosiphum padi) and a tick (Hyalomma lusitanicum). This not only supports the anti-parasitic hypothesis for beetle consumption, but suggests potential new roles for CTD, under certain conditions.

Highlights

Cantharidin (CTD) is a toxic trycyclic monoterpene with the chemical formula: 3,6-epoxy-1,2-dimethylcyclohexane-1,2-dicarboxylic anhydride (Figure 1)
CTD was one of the first pharmacoactive natural products used by humans [1,2,3], and was long considered a sexual stimulant [4,5,6,7,8]
CTD is used on humans to treat both common and molluscum warts, to remove tattoos, and as a counterirritant, and, until recently, was used as a sexual stimulant in livestock breeding [4,14]

Summary

Introduction

Cantharidin (CTD) is a toxic trycyclic monoterpene with the chemical formula: 3,6-epoxy-1,2-dimethylcyclohexane-1,2-dicarboxylic anhydride (Figure 1). CTD was one of the first pharmacoactive natural products used by humans [1,2,3], and was long considered a sexual stimulant [4,5,6,7,8]. In the late Middle Ages, Lytta vesicatoria blister beetles were collected and sold throughout Europe as an aphrodisiac, known as “Spanish Fly” (Figure 2) [9,10,11,12,13]. CTD is used on humans to treat both common and molluscum warts, to remove tattoos, and as a counterirritant, and, until recently, was used as a sexual stimulant in livestock breeding [4,14]. CTD is a powerful vesicant and highly toxic. The consumption of beetles in fresh forage or hay, or drinking beetle- contaminated water, can seriously harm pets, poultry, or livestock [16,18,22,23]

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Results

Conclusion