Revealing Biases in Insect Diversity Detection: Comparative Insights from eDNA Substrates and Malaise Traps

This study investigates the biases introduced by different substrates in assessing insect diversity, with a focus on environmental DNA (eDNA) substrates and traditional Malaise traps (MT). While MT is commonly used to capture flying insects, they often fail to sample species from cryptic or less accessible habitats. eDNA sampling has emerged as a complementary approach, but its effectiveness varies depending on the substrate. We conducted a comparative analysis of various eDNA substrates, including anthill, sediment, soil, spiderweb, water, and rot wood, alongside MT, to evaluate their ability to capture a broader spectrum of insect diversity. Our findings show that each substrate captures a distinct taxonomic composition, with significant variation in both species diversity and representation. Notably, the variation in insect order composition between substrates was greater than the variation observed across locations. Furthermore, the available reference data is predominantly biased toward species captured by MT, with limited representation of species from eDNA substrates. This study highlights the importance of integrating multiple sampling methods to mitigate biases and improve the accuracy of insect biodiversity assessments, offering critical insights for ecological monitoring and conservation efforts.