The brown marmorated stink bug, Halyomorpha halys (Stål), native to East Asia, emerged as an invasive pest in Europe in the 2000s. In its native range, Trissolcus japonicus (Ashmead) is the dominant egg parasitoid of H. halys, and thus it has been considered for classical biological control in countries invaded by the pest. A survey of native egg parasitoids conducted in 2017 and 2018 with frozen, sentinel egg masses of H. halys revealed that T. japonicus was already present in apple orchards in the Canton Ticino, Switzerland. Trissolcus japonicus was recovered in both years and from three different sites. In total, 17 egg masses were recovered from which 42 adult parasitoids emerged. A genetic analysis using the barcode mitochondrial DNA confirmed the morphological identification of T. japonicus and evidenced a best match of the "Ticino populations" to Japanese populations, but the pathways of entry remain unknown. Keywords Biological control • Egg parasitoids • Halyomorpha halys • Scelionidae Key message • Surveys for egg parasitoids of Halyomorpha halys were conducted in southeastern Switzerland. • For the first time, the Asian parasitoid T. japonicus was recovered from sentinel H. halys egg masses in Europe. • Trissolcus japonicus is established in Switzerland and was found in two consecutive years at three different sites. • Parasitism levels by T. japonicus are currently low, with a maximum of 2%. Communicated by D.C. Weber.

Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro‐ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker‐assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post‐release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy.