Metabarcoding advances agricultural invertebrate biomonitoring by enhancing resolution, increasing throughput and facilitating network inference

Biomonitoring of agriculturally important insects is increasingly vital given our need to understand: (a) the severity of impacts by pests and pathogens on crop yield and health and (b) the impact of environmental change and land management on insects, in line with sustainable development and global conservation targets. Traditional entomological traps remain an important part of the biomonitoring toolbox, but sample processing is laborious and introduces latency, and accuracy can be variable. The integration of molecular techniques such as environmental DNA and DNA metabarcoding into insect biomonitoring has gained increasing attention, but the advantages of doing so, the kind of data this can generate, and how easily and effectively molecular analyses can be integrated with the diverse types of entomological traps currently used remains relatively unclear. In this review, we examine how combining DNA metabarcoding with a range of conventional and unconventional entomological sampling techniques can advance biomonitoring in a way that is useful to researchers and practitioners. We highlight some of the key challenges and how to mitigate them, using examples of its integration with different sampling methods from the literature (e.g., interception, pitfall and sticky traps) to demonstrate efficacy and suitability. We discuss how metabarcoding data can be used to infer ecological networks, emphasizing the importance of this as a framework for understanding species interactions and ecosystem functioning for more effective and descriptive biomonitoring. Finally, future advances in biomonitoring are highlighted, alongside recommendations of best practice for researchers both new to and experienced in invertebrate biomonitoring with metabarcoding.