Use of high-resolution melting for the rapid diagnosis of thrips (Insecta: Thysanoptera) in legume crops in South Florida

Thrips (Order: Thysanoptera) are significant agricultural pests that cause severe economic losses globally through direct feeding damage and their role as vectors of orthotospoviruses. South Florida's warm climate and diverse cropping systems, particularly legume crops such as snap bean (Phaseolus vulgaris L.) and lablab (Lablab purpureus), provide favorable environment for thrips infestations. Three thrips species, Megalurothrips usitatus (Bagnall), Thrips palmi Karny, and Frankliniella insularis (Franklin) (Thysanoptera: Thripidae), are prevalent in the region, with M. usitatus being an invasive pest that poses a significant threat to leguminous crops. Accurate species identification is critical for effective integrated pest management strategies. However, morphological identification is challenging due to the small size, subtle diagnostic traits, and high phenotypic similarity among thrips species, particularly in immature stages. This study aimed to develop a rapid, reliable molecular identification tool for these thrips species using high-resolution melting (HRM) analysis, a post-polymerase chain reaction (PCR) technique that differentiates DNA sequences based on their unique melting profiles. HRM analysis enables species-specific identification by detecting genetic variations and single nucleotide polymorphisms in PCR amplicons. We optimized and validated an HRM-based assay for the precise identification of M. usitatus, T. palmi, and F. insularis using both adult and larval stages collected from leguminous crops in South Florida. The assay demonstrated high specificity, sensitivity, and reproducibility, providing a robust molecular diagnostic tool for species identification. This method has the potential to enhance pest management efforts by facilitating early detection and targeted management, reducing the economic impact of thrips on legume production in the region.