Psix striaticeps (Dodd) (Hymenoptera, Scelionidae): an Old World parasitoid of stink bug eggs arrives in Florida, USA

Psix striaticeps (Dodd) is an egg-parasitoid wasp previously known only from the Old World. We report this species from twelve counties in Florida, which are the first records in the Western Hemisphere. It was collected in yellow cylinder traps and reared from the eggs of three stink bug species: Nezara viridula L., Chinavia marginata (Palisot de Beauvois), and Piezodorus guildinii (Westwood). A COI barcode analysis found a 100% match between the Floridian population and a specimen from South Africa. The prospects of using Ps. striaticeps as a biological control agent against exotic stink bugs are discussed.

Calcatedessa gen.n. a new genus sister to Grammedessa Correia & Fernandes (Heteroptera, Pentatomidae, Edessinae) based on a cladistic analysis

Grammedessa Correia & Fernandes, 2016 is a genus raised to include some species of Edessa Fabricius, 1803 that is a very common group of stink bugs inhabiting only the Neotropical region. Grammedessa was proposed excluding a few species that were morphologically similar but not completely fitting in the diagnostic requirements of the genus. Grammedessa was also proposed without considering a phylogenetic context. In this work, the monophyly of Grammedessa was tested using a cladistic analysis, including all species that were originally excluded, under both Maximum Parsimony and Bayesian methods. As a result, six new species are now included in Grammedessa, which will be described in a forthcoming paper; Edessa botocudo Kirkaldy, 1909 was considered an unnecessary new name for Edessa hamata Walker, 1868 that was transferred to Grammedessa, resulting in G. hamata (Walker, 1868) comb.n. Calcatedessa gen.n., a new genus sister to Grammedessa, is here proposed to include four new species: C. anthomorpha sp.n., C. clarimarginata sp.n., C. germana sp.n. and C. temnomarginata sp.n. The Calcatedessa–Grammedessa clade and both genera were recovered as monophyletic by Maximum Parsimony and Bayesian methods. An identification key to the species of Calcatedessa gen.n. is provided. The new genus is distributed in Guyana, Suriname, French Guyana, and Brazil.

First record in Belgium of Trissolcus basalis (Hymenoptera, Scelionidae), an egg parasitoid of economically important stink bugs (Hemiptera, Pentatomidae)

The scelionid parasitoid Trissolcus basalis (Wollaston,1858) has been detected in Belgium for the first time based on specimens reared from a parasitized egg mass of Nezara viridula (Linnaeus,1758) collected in an urban garden at Sint-Amandsberg, Ghent. Identification was based on adult morphology and DNA barcoding. This is presently believed to be the northernmost record in Europe of T. basalis and could be the consequence of a northward expansion of this species due to climate change. This first record may be of economic importance for the biological control of stink bug pests in Belgian vegetable and fruit production.

Stink Bug Communication and Signal Detection in a Plant Environment

Plants influenced the evolution of plant-dwelling stink bugs’ systems underlying communication with chemical and substrate-borne vibratory signals. Plant volatiles provides cues that increase attractiveness or interfere with the probability of finding a mate in the field. Mechanical properties of herbaceous hosts and associated plants alter the frequency, amplitude, and temporal characteristics of stink bug species and sex-specific vibratory signals. The specificity of pheromone odor tuning has evolved through highly specific odorant receptors located within the receptor membrane. The narrow-band low-frequency characteristics of the signals produced by abdomen vibration and the frequency tuning of the highly sensitive subgenual organ vibration receptors match with filtering properties of the plants enabling optimized communication. A range of less sensitive mechanoreceptors, tuned to lower vibration frequencies, detect signals produced by other mechanisms used at less species-specific levels of communication in a plant environment. Whereas the encoding of frequency-intensity and temporal parameters of stink bug vibratory signals is relatively well investigated at low levels of processing in the ventral nerve cord, processing of this information and its integration with other modalities at higher neuronal levels still needs research attention.

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

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.