Ultrastructure of the Salivary Glands of the Stink Bug Predator Podisus distinctus

Abstract

Podisus distinctus (Hemiptera: Pentatomidae) is a zoophytophagous insect with significant potential for use as a biological control agent in agriculture and forestry because their nymphs and adults actively prey on diverse insect species. The saliva of this insect possesses active substances that cause paralysis and death of the prey. As the first step in identifying compounds of P. distinctus saliva, this study describes the ultrastructure of the salivary glands of this predator. The salivary system of P. distinctus possesses a pair of main salivary glands with a short anterior lobe, a long posterior lobe, and a pair of tubular accessory glands. The main salivary gland of P. distinctus has no associated muscles, suggesting that the saliva-release mechanism occurs with the help of certain thorax muscles. The main salivary gland epithelium has a single layer of cells (varying from cubical to columnar) with cytoplasm rich in rough endoplasmic reticulum, spherical granules of different sizes, a nucleus with a predominance of decondensed chromatin, and nucleolus. The apical cell region has a few short microvilli and the basal region has plasma membrane infoldings. The epithelium of the accessory salivary glands possesses a single-layered epithelium of cubic cells delimiting a narrow lumen. The apical cell region has a high density of microvilli and pleomorphic mitochondria, whereas the central cell region is rich in rough endoplasmic reticulum with a well-developed nucleus and decondensed chromatin. The basal cell region is characterized by the presence of several basal plasma membrane infoldings associated with mitochondria and numerous openings to the hemocoel forming large channels. The ultrastructural characteristics suggest that the main salivary glands and accessory salivary glands play a vital role in protein synthesis for saliva production and that the accessory glands are involved in transport of materials of the hemolymph.

Anatomy, Histology, and Ultrastructure of Salivary Glands of the Burrower Bug,Scaptocoris castanea(Hemiptera: Cydnidae)

“…The histology of the salivary glands of S. castanea suggests that there are three regions responsible for saliva production: the anterior and posterior lobes of the principal salivary gland and the accessory salivary gland because they have columnar secretory epithelium as reported for other Hemiptera (Azevedo et al, 2007; Serrão et al, 2008; Martínez et al, 2014, 2015).…”

“…The presence of narrow and short basal plasma infoldings associated with some mitochondria in the secretory cells of the posterior lobe and absence of them in the anterior lobe of the principal salivary gland of S. castanea are features of cells with low activity in the transport of substances of the hemolymph (Ferreira et al, 1981; Marana et al, 1997; Fialho et al, 2009), as well as occur in the salivary glands of P. distinctus (Martínez et al, 2015).…”

Gross morphology and ultrastructure of the salivary glands of the stink bug predator Eocanthecona furcellata (Wolff)

“…Compared to the principal salivary glands, these accessory salivary glands were in a form of tubes and were also narrower (Figure 1d). The salivary glands of E. furcellata is composed of a pair of principal salivary glands and a pair of accessory salivary glands that showed similar features to other Asopinae such as Podisus nigrispinus (Martínez et al, 2014), Brontocoris tabidus (Azevedo et al, 2007), Supputius cincticeps (Castro et al, 2013), and Podisus distinctus (Martínez et al, 2015). This suggested a similar anatomical pattern among predators of the Pentatomidae family.…”

“…The different feeding habits of the hemipterans (zoophagous, phytophagous, zoophytophagous, hematophagous) may be an influencing factor for the morphological diversity of their salivary glands (Cohen, 1995;Terra & Ferreira, 1994;Zeng & Cohen, 2000). The anatomical structure of the salivary glands of Asopinae species was more closely analogous (Azevedo et al, 2007;Castro et al, 2013;Martínez et al, 2014Martínez et al, , 2015, which indicated that phylogeny is an important factor in salivary glands morphology.…”

Ultrastructural analysis of salivary glands in a phytophagous stink bug revealed the presence of unexpected muscles

“…In hemipteran insects, the salivary gland complex comprises a pair of principal glands and a pair of accessory glands that produce saliva [2,6–9], which is composed of a variety of substances, including water, lipids, carbohydrates and enzymes, that promote extra-oral digestion, and maintain food consumption efficiency [2,10–12]. …”