Ultrastructural Variations of Antennae and Labia Are Associated with Feeding Habit Shifts in Stink Bugs (Heteroptera: Pentatomidae)

Abstract

The family Pentatomidae (stink bugs) is one of the largest groups in Heteroptera, containing many important pests and natural enemies. They exhibit highly diversified feeding habits and related structural modifications, but the key morphological characteristics associated with feeding habit radiation remain unclear. In the current study, we address this question by analyzing morphological variations of feeding related organs. We compare the ultrastructures of antennae and mouthparts across the chosen 17 species in Pentatomidae, representing both plant feeders and predators from four subfamilies. A strong association between ultrastructural adaptation and feeding habit transition has been revealed. The long, sharp, and hook-like mandibular teeth and maxillary barbs are exclusively present in predatory Pentatomidae, suggesting their tight association with the shift of feeding habit from phytophagy to predation. Significant differences between phytophagous and predatory species are also found in antennal and labial sensilla types and arrangements, implying their important function in food selection. Our data identify a series of key morphological structures associated with feeding habit variations among stink bugs, which will facilitate future studies on adaptive evolution of feeding habits, utilization, and population control of economic species in Pentatomidae as well as in other heteropteran lineages.

Sexual selection and predation drive the repeated evolution of stridulation in Heteroptera and other arthropods

“…Khila et al ., 2012), species and higher‐level groups (e.g. Galleti‐Lima & Guadanucci, 2019; Hemala et al ., 2021), and in adaptive shifts to accommodate different life styles (Giglio et al ., 2003; Li et al ., 2021). Based on the above, the morphological plasticity of the arthropod cuticle may be the primary developmental factor underlying the repeated evolution of stridulation in arthropods.…”

Microstructural Adaptation for Prey Manipulation in the Millipede Assassin Bugs (Hemiptera: Reduviidae: Ectrichodiinae)

“…Antennal sensilla of insects were evidenced to have the function of receiving chemical and mechanical signals from their surroundings, playing important roles in host and mate location [24,25,[45][46][47][48][49][50]. Antennal sensilla of ectrichodiines have been reported for the first time in this study.…”

“…The prepared samples were then coated with a film of gold (EIKO IB-2), and then imaged with a scanning electron microscope HITACHI S-3400N at 10 kV in the scanning microscopy laboratories of the College of Biological Science of China Agricultural University. The morphological terminology follows Cobben [21] and Schneider [22], and more specialized nomenclature from other studies was used in addition [6,[23][24][25].…”

“…Adaptive shifts of feeding habits and feeding-related organs have been hypothesized to be a main driver of true bug radiation [25,36]. The mandibular stylets not only protect and stabilize the maxillary stylets, but also play an important role in penetrating the tissues of the host/prey [21,37].…”

“…The mandibles of heteropterans are known to undergo morphological modifications to be adapted to various diet types. For instance, the prominent and stout teeth on the mandibular stylets of some pyrrhocorid species were considered to facilitate breaking hard seed coats [23,38]; the mandibular teeth of predatory pentatomids are sharp and hook-shaped, while they are short and blunt in plant feeders [25,39,40]; the blood-feeding triatomine species possess a single row of hook-shaped teeth on each mandible, used to penetrate the skin of vertebrate hosts [41]. In the current study, we have demonstrated that all examined species in Ectrichodiinae have distinctly more and denser transverse ridges on the external sides of mandibles than those in tribelocephalines.…”