Lack of evidence for chemical integration of the cuckoo-bee Stelis nasuta (Latreille, 1809) and Coelioxys aurolimbata (Förster, 1853) with their main host Megachile parietina (Geoffroy, 1785)

Megachile parietina is a solitary megachilid species, which sometimes nests in large aggregations. Such a condition attracts a diverse entomological fauna, including several parasites. Here, we focused on two cuckoo-bees of this species, Stelis nasuta and Coelioxys aurolimbata (Megachilidae) and investigated if chemical integration with the host favours their reproductive success. Lipids on the epicuticle and in the Dufour’s gland secretion, possibly contributing to protecting the eggs against dehydration, of the three species showed species- specific mixtures of long-chained linear alkanes and alkenes. Moreover, contrary to what has been reported for some cuckoo-bees of the genus Nomada, we found no evidence that the mandibular glands of parasite males contribute to female chemical mimicry. Therefore, we found no indication that chemical integration is part of the adaptive strategies of these two brood parasites.