Larval aggregations of the blister beetle<i>Stenoria analis</i>(Schaum) (Coleoptera: Meloidae) sexually deceive patrolling males of their host, the solitary bee<i>Colletes hederae</i>Schmidt &amp; Westrich (Hymenoptera: Colletidae)

Abstract

Abstract We here report on observations on the parasitism of the solitary bee Colletes hederae Schmidt & Westrich (Hymenoptera: Colletidae) by triungulins (first instar larvae) of the European beetle Stenoria analis (Schaum) (Coleoptera: Meloidae). Our observations carried out in western France provide behavioural evidence that patrolling males of C. hederae hover in front of, and are strongly drawn to, larval aggregations of S. analis in a manner reminiscent of approaching flights to emerging, conspecific females. Not only were the male bees strongly attracted to clusters of newly hatched triungulins, but they also attempted copulation (i.e., pseudocopulation) with the latter, which regularly resulted in small groups of triungulins being transferred onto the thorax of the male bees. Decent-sized groups of triungulins were exclusively found on the thorax of male bees, which suggests that triungulins of S. analis lure only males of the targeted host species, presumably by mimicking the female pheromonal cues of C. hederae. This is to our knowledge the first record of this kind of interaction for the whole West-Palaearctic, and only the second account on sexual deception between blister beetles and wild bees described to date.