First detection of Bemisia tabaci MED in Oklahoma and development of a high-resolution melting assay for MEAM1 and MED discrimination

Authors: KRAUSE-SAKATE, RENATE - Sao Paulo State University (UNESP); RUSCHEL, RAFAELA - Oklahoma State University; OCHOA-CORONA, FRANCISCO - Oklahoma State University; DE MARCHI, BRUNO - Eurofins Scientific, Inc; RIBEIRO-JUNIOR, MARCOS - Oklahoma State University; NASCIMENTO, DANIELE - Oklahoma State University; TRUJILLO, REESE - Oklahoma State University; SMITH, HUGH - University Of Florida; WALLACE, SARA - Oklahoma State University; HUTTON, SAMUEL - University Of Florida; Andreason, Sharon

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The sweetpotato whitefly is a top 10 insect pest of food, fiber, and ornamental crops worldwide. Currently, the sweetpotato whitefly is considered to be a complex of morphologically indistinguishable but genetically different species, two of which (MEAM1 and MED) are the most problematic worldwide. In this study, MED was discovered in the state of Oklahoma for the first time, demonstrating that this invasive species continues to spread, and a new tool was developed to detect and differentiate MEAM1 and MED. This discovery and new tool will be of interest to the scientific community, plant and insect diagnostic laboratory personnel, and growers.

Technical Abstract: The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a highly polyphagous crop pest now widely recognized as composed of several cryptic species. The Middle East-Asia Minor 1 (MEAM1) and the Mediterranean (MED) putative species are considered the most invasive and destructive worldwide. The MEAM1 species has long been established throughout the United States, while MED has been documented in 27 states. The main objectives of this study were to determine the status of MED in the state of Oklahoma and to develop and validate a high-resolution melting (HRM) assay for discrimination of MEAM1 and MED. In August through October of 2022, whiteflies were collected from different host plants in Stillwater, Oklahoma, and identified to species based on analysis of a diagnostic fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene. MED was found in mixed infestations with MEAM1 on sweetpotato and cucumber plants in indoor and outdoor conditions respectively. Other cryptic species were not detected. Sequencing followed by phylogenetic analysis indicated that the MED specimens belonged to the Q2 mitotype. Additionally, the secondary endosymbionts harbored in captured and progeny whiteflies were identified. For rapid discrimination of MEAM1 and MED species, an HRM assay using a single set of primer pairs targeting the mtCOI gene was developed. Species discrimination was tested using MEAM1 and MED Q2 mitotype genomic DNA and a synthetic plasmid containing the MED Q1 mitotype mtCOI fragment in two separate laboratories. The HRM assay designed in this study was validated to discriminate MEAM1 from MED Q1 and Q2 mitotypes. This is the first report of B. tabaci MED in Oklahoma and reinforces the need for continued monitoring of this insect species complex.