A preliminary comparison of blister beetle cantharidin levels in New Mexico

Blister beetles are known to be important pests of livestock, producing cantharidin, a blistering agent, which may cause death in some animals. A list of the blister beetles of New Mexico was compiled using data based primarily on specimens from the NMSU Arthropod Collection and field collections from 2007 to 2010. Over 68 species in 14 genera were recovered. The most common genus, Epicauta, appears to be well represented in alfalfa and rangeland settings and, thus, is of potential importance in cantharidin production. This study was initiated to evaluate cantharidin levels in common blister beetle species of New Mexico. In 2009 cantharidin was extracted using a protocol modified from Capinera et al. (1985). Cantharidin levels from twenty E. apache males and twenty females were compared using gas chromatography. Results indicate that there was no difference in the average cantharidin levels between sexes within this species. Also, numerically, males generally had more cantharidin than females. In females, there appeared to be an increase in cantharidin concentration as dry beetle weight decreased. In 2010, cantharidin levels were compared among species that occur in desert and rangeland settings (eg. Megetra sp., Epicauta sp., Eupompha sp.). Specimens were processed through our extraction method and cantharidin levels were evaluated. These data should provide useful information on the relative toxicity of blister beetles in New Mexico.