دانلود رایگان مقاله کشف تنوع غده سر در زنبورهای Polistine استوایی

Abstract

Exocrine glands are involved in several wasp colony activities; however, the number of known glands in the Vespidae is rather low when compared to other social insect groups. The aim of this study is to survey the head of Neotropical social wasps and to provide a detailed comparative study of the glands found in the Polistinae. A total of 33 species distributed over 13 genera were studied with serial histological sections of the head, excluding the labiomaxillary complex. Additionally, the exoskeleton was explored using scanning electron microscopy looking for associated modifications. A total of eleven exocrine glands were observed, five are structures recorded for the first time for the Hymenoptera, three are new records for the Polistinae and three are previously known organs. The glands studied are: ocellar gland I, ocellar gland II, periocular gland, subantennal gland, hypopharyngeal gland, clypeal gland, posterobasal genal gland, ectal mandibular gland, mesal mandibular gland, intramandibular gland I, and intramandibular gland II. The widespread distribution of most of these glands suggests an origin prior to the evolution of the Polistinae. Our results highlight the importance of detailed morphological studies to unveil the significance of chemical communication in one of the most characteristic groups of social animals.

4.2. Gland functions

In contrast to the extensive and detailed studies about the gland function in bees and ants, this is not the case with social wasps (Landolt and Akre, 1979). The identification of gland function could be a challenging task and several lines of evidence should be considered in this endeavor. At present we have no indications for the role of glands such as the ocellar gland I, ocellar gland II, periocular gland, and the posterobasal genal gland. Where possible, information of comparable glands reported in other social insects will be discussed for glands newly reported here for vespids. The location of the subantennal gland may suggest that this structure is related to the lubrication of the articulation. Using similar arguments, Billen (2009) has suggested that the class 1 and class 3 glands found at the joints of the legs may help the movement of these structures (Billen and Ito, 2006; Billen, 2009). The hypopharyngeal gland is exclusive to the order Hymenoptera and in bees produces the royal jelly (Jung-Hoffmann, 1966; Britto and Caetano, 2006). It is homologous to the propharyngeal gland of ants, where this is involved in the production of digestive enzymes (Ayre, 1967). A detailed structural and cytochemical study of Polistes versicolor (Olivier, 1791) by Britto and Caetano (2008) leads these authors to suggest that the hypopharyngeal gland is related to digestive functions too. In social wasps, Downing and Jeanne (1983) observed no relationship between cell size and dominance in P. fuscatus (Fabricius, 1793), and no relationship with nesting season in temperate vespines. Likewise, Britto et al. (2004) found no relationship with age in the neotropical species P. versicolor