KASP Genotyping as a Molecular Tool for Diagnosis of Cassava-Colonizing Bemisia tabaci.

Bemisia tabaci is a cryptic species complex that requires the use of molecular tools for identification. The most widely used approach for achieving this is the partial sequencing of the mitochondrial DNA cytochrome oxidase I gene (COI). A more reliable single nucleotide polymorphism (SNP)-based genotyping approach, using Nextera restriction-site-associated DNA (NextRAD) sequencing, has demonstrated the existence of six major haplogroups of B. tabaci on cassava in Africa. However, NextRAD sequencing is costly and time-consuming. We, therefore, developed a cheaper and more rapid diagnostic using the Kompetitive Allele-Specific PCR (KASP) approach. Seven sets of primers were designed to distinguish the six B. tabaci haplogroups based on the NextRAD data. Out of the 152 whitefly samples that were tested using these primer sets, 151 (99.3%) produced genotyping results consistent with NextRAD. The KASP assay was designed using NextRAD data on whiteflies from cassava in 18 countries across sub-Saharan Africa. This assay can, therefore, be routinely used to rapidly diagnose cassava B. tabaci by laboratories that are researching or monitoring this pest in Africa. This is the first study to develop an SNP-based assay to distinguish B. tabaci whiteflies on cassava in Africa, and the first application of the KASP technique for insect identification.