Evidence for Upholding the Association of Whitefly Species Bemisia tabaci and Trialeurodes vaporariorum with Tomato Yellow Leaf Curl Virus

Robin , Rakesh Kumar, Shelly Kapoor and Anil Handa

Background and Objective: Tomato yellow leaf curl virus, a member of the genus Geminivirus is known for a steep decline in tomato yield recorded during the past two decades around the globe and for influencing the horticulture industry. Bemisia tabaci (silver leaf whitefly) is known to be the major insect vector transmitting TYLCV. Apart from it, the greenhouse whitefly (Trialeurodes vaporariorum) has also been encountered feeding and rearing on tomato plants in cool temperate regions of Himachal Pradesh raising doubts about the spread of TYLCV via these vectors in these areas. The present investigations were therefore carried out to understand the virus vector relationship between the two whitefly species of the warmer and colder regions with TYLCV on tomatoes using serological and molecular tools. Materials and Methods: One hundred leaf samples and 3-5 whitefly species were randomly collected from 50 locations in three Districts Una, Solan and Sirmour of Himachal Pradesh and tested using DAS-ELISA against TYLCV antisera. Positive culture of TYLCV was maintained and used to test the transmission efficacy of whitefly vectors over varying inoculation access periods and whitefly vectors were also characterized on a molecular basis using polymerase chain reaction. Results: Disease incidence ranged between 2.5-90% and pest incidence from 10-80% in the case of each whitefly sp. and TYLCV was detected in most of the plants tested whereas B. tabaci recorded the highest concentration of TYLCV in comparison to T. vaporariorum. Transmission efficacy also remained highest for B. tabaci within the inoculation access period of 4 hrs and T. vaporariorum failed to transmit TYLCV even after 24 hrs of feeding. The PCR also successfully characterized these two whitefly vectors proving them to be different not only on morphological characters but on a molecular basis as well. Conclusion: The TYLCV has been found prominent in warmer areas and actively spread by B. tabaci posing a serious concern for farmers T. vaporariorum remains a non-concerned pest for the farmers.

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