Sunn Hemp Mosaic Virus Vector

📖 Description

Bemisia tabaci, the Silverleaf Whitefly or Tobacco Whitefly, is one of the most agriculturally destructive insects in the world and the single most important vector of plant viruses in tropical and subtropical agriculture. The species is actually a cryptic species complex comprising at least 40 genetically distinct but morphologically indistinguishable biotypes — the most damaging in India are the indigenous Asia I and Asia II-1 biotypes and the invasive MEAM1 (formerly ‘B biotype’), which was introduced in the 1990s and has since become widespread. B. tabaci is the vector of over 300 plant viruses, primarily begomoviruses (Geminiviridae) — including the Sunn Hemp Mosaic Virus (SHMV), a potyvirus transmitted in a non-persistent manner. Sunn hemp (Crotalaria juncea) is one of India’s most important green-manure crops, grown on over 2 million hectares primarily as a 60–90 day smother-and-incorporate crop before rice or sugarcane. The crop fixes 100–150 kg nitrogen per hectare in 60 days and is essential to the nitrogen economy of low-input rice systems. SHMV infection reduces both biomass production and nitrogen fixation, directly compromising the crop’s value as a green manure. The virus-vector complex is particularly challenging because the whitefly can acquire and transmit SHMV in probe-feeding episodes as short as 30 seconds, making insecticide-based vector control largely futile once infection has begun — management must focus on preventing infection through use of virus-free seed, removal of virus reservoirs, and reflective mulches that repel landing adults.