Indian Journal of Virology

Potato stem necrosis disease (PSND) caused by Groundnut bud necrosis virus (GBNV) is a threat for early potato crop. The virus is not tuber borne but readily transmitted by thrips, mainly T. palmii and inefficiently by Scirtothrips spp., but not Megalurothrips distalis and T. hawaiiensis. Monitoring of thrips was conducted during 2001–2004 at ARS, Kota, Rajasthan, with potato Kufri Bahar by weekly sampling and identification of thrips. Mass movement of thrips was observed on early-staggered plots of potatoes. Bioassay confirmed most of them to be viruliferous mainly T. palmii. Later Scirtothrips were also found together. Maximum vector activity was noticed as soon as plants emerged around 17^th October but the population continued declining in plots planted every week from 2^nd October onwards. Consequently maximum incidence and index of the disease was recorded in plots planted from 2^nd to 30^th October, but had a descending order. The thrips population again increased slightly from November though without significant increase in the disease incidence possibly because of prevalence of only the cold loving and inefficient and/or non-vector thrips as confirmed by bioassay and identification. Epidemiological implications of the above findings will be discussed.