Sustainable strategies such as classical or augmentative biological control are currently being evaluated for the long-term management of the alien invasive pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). A three-year study carried out in northeastern Italy was performed to investigate the distribution and field performance of the H. halys egg parasitoid Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae), in comparison with other parasitoid species. In the study area, adventive populations of T. mitsukurii were present since 2016, representing the earliest detection of this species in Europe. Trissolcus mitsukurii was the most abundant parasitoid and showed a higher “parasitoid impact” (i.e., number of parasitized eggs over the total number of field-collected eggs) compared to the other species, i.e., Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae), Trissolcus basalis (Wollaston) and Trissolcus kozlovi Rjachovskij (Hymenoptera: Scelionidae). The hyperparasitoid Acroclisoides sinicus (Huang and Liao) (Hymenoptera: Pteromalidae) was also recorded. Phylogenetic analysis of T. mitsukurii population distinguished two clades, one covering samples from Italy, Japan and China, the other from South Korea. The present study provides promising results for the biological control of a pest that is having a dramatic impact on a wide range of crops worldwide.

The brown marmorated stink bug Halyomorpha halys is an invasive agricultural pest with a worldwide distribution. Classical biological control has been identified as the most promising method to reduce the populations of H. halys. Adventive populations of two candidates for releases, Trissolcus japonicus and Trissolcus mitsukurii, have recently been detected in Europe. To assess their distribution and abundance, a large-scale survey was performed. From May to September 2019, a wide area covering northern Italy and parts of Switzerland was surveyed, highlighting the expanding distribution of both Tr. japonicus and Tr. mitsukurii. Within four years after their first detection in Europe, both species have rapidly spread into all types of habitats where H. halys is present, showing a wide distribution and continuous expansion. Both exotic Trissolcus showed high levels of parasitism rate towards H. halys, while parasitization of non-target species was a rare event. The generalist Anastatus bifasciatus was the predominant native parasitoid of H. halys, while the emergence of native scelionids from H. halys eggs was rarely observed. The presence of the hyperparasitoid Acroclisoides sinicus was also recorded. This study provided fundamental data that supported the development of the first inoculative release program of Tr. japonicus in Europe.

Halyomorpha halys is an invasive, widespread stink bug for which only short-term solutions are currently available for pest control worldwide. The need for long-term management solutions for H. halys has driven studies on augmentative and classical biological control of this species, especially by its egg parasitoids. Numerous investigations in Asia, USA, and Europe on native and exotic egg parasitoids of H. halys, and the effects on non-target pentatomids, have improved the global knowledge of parasitoid-host relationships, uncovered new associations, and led to the discovery of new species. This trend continues with Acroclisoides sinicus, a pteromalid that was described in the 1980's from Asia. In this work we report recent findings of this species in North America and Europe. Moreover, we propose that Acroclisoides solus syn. nov., a species described originally from the USA, is conspecific with A. sinicus based on morphological and molecular analysis.

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Animal body size commonly exhibits a remarkable variation in response to environmental conditions. Latitude, when correlated with temperature, rainfall and seasonality, represents one of the main determinants of variation in body size, as well as in allometry. It has long been recognised that populations of larger body size are found in colder environments (Bergmann's Rule), a cornerstone of evolutionary ecology. However, the way in which latitude might influence investment in exaggerated weapons of animals has received little attention. The European stag beetle Lucanus cervus (Linnaeus, 1758) is the focus of this study. Males of this species exhibit exaggerated mandibles, mainly used as weapons during intra-sexual conflicts. Five populations ranging from northern Italy to the southern limit of the distribution of L. cervus were analysed. Combining morphological and phenological data, latitudinal variation in body size, weapon investment and activity period of the adults were evaluated. The analysis of the allometry of mandibles strongly supported the presence of two male morphs. Large males (major morph) invest significantly more in weapons compared to males of the minor morph. Consistent with Bergmann's Rule, these results confirmed that

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Cold winter temperatures can influence insects’ survival in temperate zones. Brown marmorated stink bug, Halyomorpha halys (Stål) overwinters as adults in natural and human-made structures. In this study, we characterized low temperature mortality rates of H. halys adults that were either entering (ENA) or exiting (EXA) overwintering microhabitats. We considered the effect of different duration of cold exposure on mortality. We determined the impact of insect nutritional status and weight on cold tolerance. We additionally evaluated the effects of cold exposure on H. halys adult longevity and fecundity. Mortality of ENA and EXA adults was determined for 6 h and 2 h periods at − 2.5 °C and 2.5 °C respectively. EXA adults displayed higher mortality rates compared to ENA individuals at the low-temperature regimes. Halyomorpha halys adult survival rate was higher when their nutrient index (EXA individuals only) and weight were high. Low-temperature exposure increased longevity, but reduced fecundity of ENA females. The data further highlight how extreme spring frost events can result in significantly increased mortality levels of H. halys adults.

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