A morphological, biological and molecular approach reveals four cryptic species of Trissolcus Ashmead (Hymenoptera, Scelionidae), egg parasitoids of Pentatomidae (Hemiptera)

Accurate identification of parasitoids is crucial for biological control of the invasive brown marmorated stink bug, Halyomrpha halys (Stål). A recent work by Talamas et al. (2017) revised the Palearctic fauna of Trissolcus Ashmead, egg-parasitoids of stink bugs, and treated numerous species as junior synonyms of T. semistriatus (Nees von Esenbeck). In the present paper, we provide a detailed taxonomic history and treatment of T. semistriatus and the species treated as its synonyms by Talamas et al. (2017) based on examination of primary types, molecular analyses and mating experiments. Trissolcus semistriatus, T. belenus (Walker), T. colemani (Crawford), and T. manteroi (Kieffer) are here recognized as valid and a key to species is provided. The identification tools provided here will facilitate the use of Trissolcus wasps as biological control agents and as the subject of ecological studies

Geometric Generalization of the Nelder-Mead Algorithm

The Nelder-Mead Algorithm (NMA) is an almost half-century old method for numerical optimization, and it is a close relative of Particle Swarm Optimization (PSO) and Differential Evolution (DE). Geometric Particle Swarm Optimization (GPSO) and Geometric Differential Evolution (GDE) are recently introduced formal generalization of traditional PSO and DE that apply naturally to both continuous and combinatorial spaces. In this paper, we generalize NMA to combinatorial search spaces by naturally extending its geometric interpretation to these spaces, analogously as what was done for the traditional PSO and DE algorithms, obtaining the Geometric Nelder-Mead Algorithm (GNMA)

Assessing the distribution of exotic egg parasitoids of Halyomorpha halys in Europe with a large-scale monitoring program

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