Environmental DNA from ethanol eluent of flowers reveals a widespread diversity in cowpea associated animal communities in Hainan Island

Cowpea ( Vigna unguiculata (L.) Walp.), as an economical crop, is one of the important pillar industries of rural revitalization strategy in China. However, cowpea planting in China is often infested and damaged by many insects during growth, especially in Hainan region with a warm and wet tropical climate. Traditional monitoring methods with technical limitation could only detect a few common significant agricultural pests, how many kinds of species associated with cowpea is unknown. Here, we employed environmental DNA (eDNA) metabarcoding to characterize cowpea associated animal community-level diversity among six planting areas in Hainan. In all, 62 species were detected, of which 99.05% was Arthropoda, suggesting that Arthropods are the main groups interacting with cowpea. Moreover, we also detected 28 pests on cowpea, predominantly belonging to Thysanoptera, Lepidoptera, Diptera and Hemiptera, of which 20 pests were first reported and need more extra attention. Furthermore, clustering results indicated that there is a certain diversity of cowpea associated animals in different regions of Hainan, but the species composition was similar in the large planting areas due to the indiscriminate use of pesticides, which need further develop scientific pesticide applications to ensure adequate species diversity. This study represents the first molecular approach to investigate the cowpea associated animal communities and provides basic information for further scientific pesticide applications.