Identification and characterization of novel resistant genotypes of Gymnema sylvestre (Retz.) R. Br. ex Sm. against invasive mealybug species, Phenacoccus solenopsis Tinsley and Paracoccus marginatus Williams and Granara de Willink for sustainable pest management

Madhunashini, Gymnema sylvestre R. Br. ex Sm. (F: Asclepiadaceae) is an important industrial medicinal plant that has various pharmacological properties like antidiabetic, antiobesity, anticarcinogenic and neuroprotective. The invasive mealybugs, i.e., Phenacoccus solenopsis and Paracoccus marginatus, are causing significant yield losses to G. sylvestre in India. The identity of the mealybug species, P. solenopsis and P. marginatus, were confirmed both morphologically and molecularly by using Cytochrome c oxidase subunit I (COI) gene with (GenBank Accession No. OQ349395 and OQ358124). The pest incidence occurs throughout the year, but its peak activity was observed during the summer months (April to August). In the current investigation, 30 genotypes were examined for their resistance against mealybugs in their natural field environment for three consecutive years from 2019 to 2021 in the geographical region of Anand, Gujarat, India. The pooled analysis showed that the severity of infestation ranged between 0.41 and 3.57. Our study results revealed that 10% of the genotypes i.e. DGS-18, DGS-26, and DGS-28, were highly resistant. Furthermore, 16.66% of the genotypes, i.e. DGS-13, DGS-15, DGS-22, DGS-30, and DGS-33 were categorized as resistant. The novel resistant genotypes identified in the present study will be helpful for the management of P. solenopsis and P. marginatus, in G. sylvestre. The resistant genotypes have excellent scope for reducing the use of pesticide usage as well as help in mitigating pesticide residue.