Whitefly infestation:"The white epidemic"

Why in news:

Because it has become the reason of large-scale damage of cotton crops in northern India especially in Punjab.

What is Whitefly:

• It is a small white coloured insect affecting cotton and vegetables found in tropical and subtropical regions.
• They belong to Hemiptera family and feed the undersides of leaves.They feed by tapping into  phloem(a tissue responsible for distribution of food and water in plants) of plants ,introducing toxic salvia.
•  Further damage can be done by the mold growth encourage by honewdew which whiteflies secrete.
• They used to congregate in large numbers so a plant can be damaged within no time.

Recent case:

Though the crop has been damaged by whiteflies but various factors have provided the congenial room to whiteflies infestation. Many environmentalist are claiming that the Bt technology is the main cause and it also got support from farmers who are using non Bt-cotton. But it seems to be only the half picture.

• As per CICR(Central Institute for Cotton Research) the use of cotton hybrids especially issued by private commercial entities which do not follow the rigorous screening for whiteflies or leaf curl virus are the major cause of today's problem. There are over 250 Bt cotton hybrids on the shelf in North India. More than 90 per cent of these are susceptible to, and have even become hotspots for, whitefly and leaf-curl virus.
• Further late sowing(esp in Punjab) provided hot humid cloudy condition(tender season in July-August) which is a congenial weather to whitefly.
• Moreover excessive irrigation and urea application promoted fresh vegetative growth and allowed whiteflies to proliferate (as whiteflies prefer early leaves).
• Excessive use of pesticides also killed the natural enemies of whiteflies. Scientific studies show that 50-60 per cent of populations are controlled by natural enemies and 20-30 per cent displaced by rains and winds. 

What should be the approach:

• Whiteflies are physically delicate and can be controlled even with water sprays. So the  best approach is to select methods(avoiding broad spectrum pesticides) causing least disturbance to beneficial insects that can control the whitefly naturally.
• Along with that cotton seeds must subjected to rigorous screening as it affects not only our agro produce but also the environment, farmer’s life(as cases of farmers suicide already visible).

Source:Wiki,Indian Express