By Kollegala Sharma
The persistent pests of mustard plants in the Gangetic plain come raiding all the way from the Himalayas, a new study has revealed.
Researchers from the Kolkata-based Bose Institute have retraced the aerial path these marauders of mustard take and have found the exact route of their travel from the upper Himalayas down to the plains of the Ganges where they attack the popular commercial crop of the region.
Aphids are well known pests of mustard plants around the world. In India, they are known to cause huge losses to mustard. The chief tormentor of mustards is a species known as Lipaphys erisimi. There is no mustard variety that can withstand its attack. The crop losses due to this pest alone range from 39% to 91% crop, according to scientists. Starting December when first seeds are sown, the pest can be seen affecting mustard through the season till the end of March.
[...]
Why does this happen? “Temperature works as a rate limiting factor in the whole migration process of aphids,” surmises Prof. [Samir Ranjan Sikdar, who led the research team]. “Lower temperature drives the aphid to migrate from the freezing part of western Himalaya to the upper portion of Indo Gangetic Plains during November. And the spreading wind patterns help it to escape the cold.”
[...]