Host plant use of a polyphagous mirid, : Molecular evidence from migratory individuals.

While the host plant use of insect herbivores is important for understanding their interactions and coevolution, field evidence of these preferences is limited for generalist species. Molecular diet analysis provides an effective option for gaining such information, but data from field-sampled individuals are often greatly affected by the local composition of their host plants. The polyphagous mirid bug (Meyer-Dür) seasonally migrates across the Bohai Sea, and molecular analysis of migrant bugs collected on crop-free islands can be used to estimate the host plant use of across the large area (northern China) from where these individuals come. In this study, the host plant use of adults was determined by identifying plant DNA using a three-locus DNA barcode (L, H-A, and ITS) in the gut of migrant individuals collected on Beihuang Island. We successfully identified the host plant families of adults, and the results indicated that captured bugs fed on at least 17 plant families. In addition, gut analyses revealed that 35.9% of individuals fed on multiple host plants but that most individuals (64.1%) fed on only one plant species. Cotton, L., DNA was found in 35.8% of the bugs examined, which was much higher than the percentage of bugs in which other host plants were found. Our work provides a new understanding of multiple host plant use by under natural conditions, and these findings are available for developing effective management strategies against this polyphagous pest species.