Comparative transmission of Bhendi yellow vein mosaic virus by two cryptic species of the whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae).

The leaf sample from okra plants showing prominent yellow vein mosaic symptoms and healthy plant without any virus symptoms were collected from farmer's field. The presence of begomovirus in the infected sample was confirmed by polymerase chain reaction (PCR) and the amplicons were cloned and sequenced. The genome analysis showed that the isolate in the present study had 99% nucleotide identity with Bhendi yellow vein mosaic virus (BYVMV) revealing it as BYVMV variant. The genetic species of Bemisia tabaci collected from fields were identified as Asia-1 and MEAM-1 genetic species based on silver leaf assay, sequence characterized amplified region marker, and mtCOI gene sequence. The comparative virus-vector relationship of both genetic species of B. tabaci indicates a minimum of two and three B. tabaci in MEAM-1 and Asia-1 genetic species, respectively, per plant were required to transmit the disease. The minimum acquisition access period and inoculation access period of 15 (MEAM-1) and 20 min (Asia-1) were required to transmit the YVMD; it was further confirmed by nucleic acid hybridization using coat protein gene-specific probe of BYVMV. With respect to the sex, the female B. tabaci were more efficient in transmitting the disease as compared to male ones in both the genetic species of B. tabaci. The MEAM-1 to transmit the BYVMV more efficiently than Asia-1 genetic species of B. tabaci.