Morphology of mandibular and intramandibular glands in workers and virgin queens of Melipona scutellaris

Abstract

The interactions of insect societies are associated with chemical signals released by the exocrine glands that control some insect behaviors. Exocrine glands can be classified into different classes: class I release substances that cross the body cuticle and class III glands that have a conducting canal. This study compares the morphology of intramandibular and mandibular glands in virgin queens of different ages, as well as in nurses and forager workers of Melipona scutellaris. We have found the occurrence of two types of glands inside the mandible; glands of class I, corresponding to a well-developed epithelium, secretory only in virgin queens, and glands of class III. On the other hand, mandibular glands have been found to be well-developed in workers and queens and they also have high amounts of mitochondria and smooth endoplasmic reticulum. Together, these data show that the mandibular and intramandibular glands of M. scutellaris virgin queens have morphological features that indicate the synthesis of compounds that are lipid in nature. Furthermore, both glands have a similar developmental degree in newly emerged and 7-day-old ones.

Intramandibular glands in different castes of leaf‐cutting Ant, Atta laevigata (Fr. Smith, 1858) (Formicidae: Attini)

“…The occurrence of intramandibular glands of class‐3 in A. laevigata corroborates that the presence of these glands is a common feature in social Hymenoptera, as they have been reported in bees (Costa‐Leonardo, ; Cruz‐Landim and Abdalla, , 2011; Romani et al, ; Smith et al, ; Wossler et al, ), wasps (Romani et al, ; Santos et al, ) and ants (Billen, ; Billen and Delsinne, ; Billen and Espadaler, ; Grasso et al, ; Marques‐Silva et al, ; Martins and Serrão, ; Martins et al, ; Roux et al, ; Schoeters and Billen, ; Toledo, ).…”

Field-relevant doses of the systemic insecticide fipronil and fungicide pyraclostrobin impair mandibular and hypopharyngeal glands in nurse honeybees (Apis mellifera)

“…Pesticide-linked alterations to brood-food glands can harm brood care through a reduction in royal jelly quantity/quality, which can threaten caste differentiation, bee development, and colony maintenance, all contributors to high colony losses worldwide 4 , 67 , 68 . We highlight that royal jelly production is related to the development of mandibular and hypopharyngeal glands of nurse honeybees 36 , 38 , 40 , 52 , 53 , 69 and emphasize the importance of direct royal jelly measurement in colonies exposed to pesticides in future studies to evaluate its quantity and quality.…”

“…Specifically, we examined secretory-cell height and reservoir volume of the mandibular glands as well as acini size and number in the hypopharyngeal glands. Cell height of the mandibular glands is a main indicator of development and secretory activity of these glands 38 , 52 , whereas acini size in hypopharyngeal glands indicates activity and the amount of royal jelly secreted 36 , 38 , 40 , 53 , 54 .…”

The relationship between queen execution and cuticular hydrocarbons in stingless bee Melipona scutellaris (Hymenoptera: Meliponini)

“…Therefore, behavioral studies are important for future management of this threatened stingless bee. We collected two colonies of M. scutellaris in 2007 and started studies of its biology (Sousa et al 2013;Santos et al 2015). We here show that excess virgin queens are killed by workers, a phenomenon triggered by a change in CHC profiles of virgin queens during the first days of their life.…”