Ants as prey for the endemic and endangered Spanish tiger beetle Cephalota dulcinea (Coleoptera: Carabidae)

Abstract

Among the insects inhabiting endorheic, temporary and highly saline small lakes of central Spain during dry periods, tiger beetles (Coleoptera: Carabidae: Cicindelinae) form particularly rich assemblages including unique endemic species. Cephalota dulcinea López, De la Rosa & Baena, 2006 is an endemic, regionally protected species that occurs only in saline marshes in Castilla-La Mancha (Central Spain). Here, we report that C. dulcinea suffers potential risks associated with counter-attacks by ants (Hymenoptera: Formicidae), while using them as prey at one of these marshes. Through mark–recapture methods, we estimated the population size of C. dulcinea at the study marsh as of 1352 individuals, with a sex ratio slightly biased towards males. Evident signs of ant defensive attack by the seed-harvesting ant Messor barbarus (Forel, 1905) were detected in 14% of marked individuals, sometimes with cut ant heads still grasped with their mandibles to the beetle body parts. Ant injuries have been more frequently recorded at the end of adult C. dulcinea yearly activity, and in similar proportions in males and females, perhaps because the similar body mass of the two sexes makes the output of interactions similar. Because antennae and tarsi were particularly involved in such injuries, consequences on both chemosensory and locomotion abilities may be expected. Future studies may discover if ants are effectively a costly prey for this endangered tiger beetle.