Copy number variation of two begomovirus acquired and inoculated by different cryptic species of whitefly, Bemisia tabaci in Okra

The whitefly, B.tabaci is a major pest of agricultural crops which transmits begomovirus in a species-specific manner. Yellow vein mosaic disease (YVMD) and okra leaf curl disease (OLCD) caused by distinct begomovirus are a major limitation to production of okra in India. In this framework the present investigation reports, for the first time, comparative study of begomovirus species viz. yellow vein mosaic virus (YVMV) and okra enation leaf curl virus (OELCuV) ingested and egested by two cryptic species (Asia I and Asia II 5) of B.tabaci at different time interval using detached leaf assay. A gradual increase of both virus copies were observed with increased feeding exposure in Asia I and Asia II 5. Both the genetic groups of whitefly could acquire the viruses within just 5 minutes of active feeding however, a significant amount of variation was noted in virus uptake by the both. At 24 hours of active feeding Asia II 5 acquired more of YVMV whereas, Asia I ingested more OELCuV. Similarly, the genetic group acquiring higher titre of virus egested higher amount during inoculation period. On the whole, it can be presumed that Asia I is a more effective transmitter of OELCuV whereas, Asia II 5 of YVMV further suggesting increased risk of virus pandemics (both YVMV and OELCuV) in regions where Asia I and Asia II 5 is dominant.

Automated summary

This study compares the ingestion and egestion of yellow vein mosaic virus and okra enation leaf curl virus by two cryptic species of whitefly. The results show that both species of whitefly can acquire the viruses within a short feeding time, but the amount of ingestion varies. Different genetic groups of whitefly acquire different types and quantities of virus after 24 hours of feeding. Asia I is found to be a more effective transmitter of okra enation leaf curl virus, while Asia II 5 is a more effective transmitter of yellow vein mosaic virus.