Unraveling the diet secrets of predatory mites through metabarcoding: Current state and perspectives

The efficiency of biological control programs can be compromised by a lack of information on trophic interactions among natural enemies. Despite the importance of predatory mites as biological control agents, many ecological aspects, such as their diet in the field, remain poorly known. Most of our knowledge on this subject comes from laboratory tests. However, these approaches are often challenging to perform, time-consuming, and do not fully represent interactions in field conditions. Tools that allow to determine the diet of predatory mites in situ are highly desirable. One promising avenue for achieving this is DNA metabarcoding. While this approach has been successfully applied to insects, it is still in its early stages of development for mites. Applying these techniques to predatory mites presents challenges due to their small size and feeding mode, particularly pre-oral digestion, which partially degrades ingested DNA. In this presentation, we will discuss recent advancements in the application of metabarcoding to uncover the preys of predatory mites (including both mites and small insects) in the Phytoseiidae family. Specifically, we will cover three main topics: i) the design and validation of primers that target specific groups to enhance the detectability of phytophagous mites as prey; ii) the evaluation of how various biotic and abiotic factors, such as taxa, temperature, and post-feeding time, affect detectability; and iii) the effectiveness of this approach in detecting multiple prey species. Additionally, we will explore the potential for applying this approach to study other types of diets and different groups of predatory mites.