Validation of a species-specific mtCOI marker for the identification of cassava mealybug, Phenacoccus manihoti matile-ferrero (Hemiptera: Pseudococcidae)

The invasive mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), has emerged as a serious pest of the cassava crop, with its recent incursion into India prompting heightened concerns. This study validated a species-specific mtCOI marker (SS-mtCOI) to identify P. manihoti during its nymphal stage. A comprehensive survey was conducted across several districts of Kerala to collect specific samples of P. manihoti nymphs from cassava and alternative host plants. Subsequently, the SS-mtCOI marker was employed to evaluate the efficacy of this marker across various populations of P. manihoti in Kerala, utilizing extracted DNA and polymerase chain reaction (PCR) analysis for validation. This marker successfully identified all developmental stages (egg, first, second, third instar, and adult female), even at low DNA concentrations. This validation of the SS-mtCOI marker through PCR assay provides a quick, clear, and reliable method for identifying P. manihoti, eliminating the need for traditional slide mounting.