Morphological diversity of the labial sensilla of phytophagous and predatory Pentatomidae (Hemiptera: Heteroptera), with reference to their possible functions

Abstract

Sensory structure on the labial surface of five genera of Pentatomidae (Hemiptera: Heteroptera) belonging to two subfamilies i.e. Asopinae and Pentatominae have been studied using Scanning Electron Microscopy. Three representatives of the subfamily Pentatominae (phytophagous)-Dolycoris indicus (Stal), Plautia crossota (Dallas) and Piezodorus hybneri (Gmelin) and two of Asopinae (predatory)-Perillus bioculatus (Fabricius) and Eocanthecona furcellata (Wolff) were studied to morphologically characterize and compare the sensory structures present on the labium. Six types of labial sensilla were found on their labial tip and surface. The labial sensilla identified were sensilla peg (SP), basiconica (SB), campaniformia (SCa), chaetica (SCh), styloconica (SStc) and trichodea (ST). Their possible functions were discussed relating to morphology and location. A new form of sensilla basiconica was also observed in D. indicus. Sensilla styloconica were restricted only to the predatory pentatomid bugs. Cuticular projections (Cpr) on the sensorial region of the studied pentatomids were also observed along with labial cuticular pores.

Fine structure of mouthparts and feeding performance of Pyrrhocoris sibiricus Kuschakevich with remarks on the specialization of sensilla and stylets for seed feeding

“…sibiricus , sensilla trichodea II and sensilla basiconica IV. Sensilla trichodea with flexible sockets in the subapical region of the labium in this species appear to be identical to those of other heteropterans [6,13,31,46,47], in which the structure indicates a contact chemoreceptive function. Twenty-four sensilla basiconica are found in two sensory fields, as reported in the pyrrhocorids D .…”

“…High sensillar diversity and /or abundance on the labium have been observed in other hemipterans, and these apparently perform both chemosensory and mechanosensory functions, during probing with the labium during plant surface exploration [4,6,13,15, 29–31,36,45–49]. Detailed morphological descriptions of pyrrhocorid mouthpart sensilla have never been reported.…”

“…sibiricus . Similar sensilla in Peiratinae (Reduviidae) have been shown to have a proprioreceptory function [48] and such mechanosensory sensilla also occur in phytophagous Pentatominae and predatory Asopinae (Pentatomidae) [31]. In pyrrhocorids, such sensilla probably act as proprioceptors responding to the stresses arising from the movement of the labium.…”

Morphological Disparity of the Mouthparts in Polyphagous Species of Largidae (Heteroptera: Pentatomomorpha: Pyrrhocoroidea) Reveals Feeding Specialization

“…The labial tip sensilla in pyrrhocorids and largids usually consist of 11 to 12 sensilla basiconica (Sb4) and one sensilla trichodea (St2), except in Dysdercus fasciatus [29] and Odontopus nigricornis Stål [33], with 10 sensilla basiconica. Significantly more numerous sensilla basiconica, ranging from 16 to 22, have been reported in other species of pentatomomorphans (in the alydid Riptortus pedestris F. and the lygaeid Elasmolomus sordidus (F.) [35]; in the pentatomid Nezara viridula L. [33], and in Blissus leucopterus (Say)) [54]. Sensilla basiconica or peg sensilla usually have the same function (gustatory) on the labial tip, but they differ in quantity among the mentioned species.…”

“…Such behavior supports the idea that the sensilla of the labial tip provide essential information about the chemical composition of the substrate. Furthermore, several researchers [33,35,[49][50][51][52] have determined that the apical labial sensilla receptors of feeding and seed-sucking insects are important chemical and mechanical receptors in host selection and feeding in hemipteran species.…”