Comparative morphology of the head glands in species of Protepeolini and Emphorini (Hymenoptera: Apidae)

The tribe Protepeolini is formed by parasitic bees with Leiopodus being the only genus of the tribe. Protepeolini bees parasitize the nests of members of the tribe Emphorini. Secretions of the head glands are important to the biology of bees as they may act as chemical signals in parasitism strategies. In this paper, we describe the morphology and histoarchitecture of head glands in three Protepeolini species and compare them with those of their Emphorini hosts. Mandibular and hypopharingeal glands were identified , but no head salivary glands were observed. Only parasitic species displayed sexual dimorphism in the morphology of mandibular glands, with males showing well-developed secretory portions and a characteristic organization of the secretory tissue which was previously unknown in bees. The possible role of mandibular head glands is discussed in relationship to behavioral parameters of Leiopodus.