Monitoring invertebrate pests on cowpea crops across China using eDNA metabarcoding.

Monitoring arthropod pests and their natural enemies provides essential information for pest control decisions in agricultural production. Traditional monitoring methods, such as trapping and visual surveys, have practical limitations because of their time-consuming preprocessing steps and the need for knowledgeable taxonomists. We tested the environmental DNA (eDNA) metabarcoding approach for monitoring cowpea (Vigna unguiculata) arthropod pests and their natural enemies across seven climatic sub-regions of China, comparing it with traditional sample collection and morphological identification methods. We showed that eDNA metabarcoding reveals a higher species richness of cowpea arthropods than the traditional visual method. The eDNA method detected 163 species, of which 72, 33 and 57 were pests, natural enemies and other insects, respectively, whereas the traditional method only detected 70 species. There were significant differences in alpha- and beta-diversity for arthropods on cowpea in different climatic sub-regions. We also found that longitude, altitude and geographical distance are associated with species diversity, but latitude, mean air temperature and temperature range are not. This study represents the first use of eDNA metabarcoding to investigate cowpea arthropod communities, providing a novel method for pest monitoring. © 2025 Society of Chemical Industry.