Assessing thrips diversity and diagnosis in leguminous crops across South Florida, Central America, and the Caribbean

Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae) is a thrips species native to the tropical regions of Asia. In the Americas, it was first reported in Florida in 2020 and has since been identified in several Central American and Caribbean countries. To understand the distribution and genetic diversity of M. usitatus populations, specimens were collected from Phaseolus vulgaris and Lablab purpureus in South Florida. Additional specimens from various legume hosts in Guatemala, Honduras, Nicaragua, and Puerto Rico were also evaluated. To assess the presence and abundance of M. usitatus, flower samples were collected at each site, and both adult and larval thrips were counted. From each locality, 20 specimens were analyzed at the molecular level using universal primers HCO2198/C1-J-1718 targeting the mitochondrial cytochrome oxidase I (mtCOI) gene. All specimens were slide-mounted, and adult thrips were morphologically identified. To support integrated pest management (IPM) efforts, this study also aimed to develop a rapid and accurate molecular identification method for the three main thrips species prevalent in South Florida: M. usitatus, Thrips palmi, and Frankliniella insularis. We optimized and validated a high-resolution melting (HRM) analysis-based assay for the precise identification of these species from leguminous crops. The assay demonstrated high specificity, sensitivity, and reproducibility, providing a robust molecular diagnostic tool for thrips identification. This method has the potential to improve pest management by enabling early detection and targeted control measures, ultimately reducing the economic impact of thrips on legume production in the region.