Cola Drinks had been used as Insecticides

Agricultural scientists said that the high sugar content of the cola drinks can be very effective in combating pests.
Unsurprisingly, Pepsi and Coca-Cola strongly disagree, saying there is nothing in the drinks that can be used in pest control.

Facts

Farmers in the Durg, Rajnandgaon and Dhamtari districts of Chhattisgarh say they have successfully used Pepsi and Coke to protect their rice plantations against pests.
It is a trend that has been seen in other parts of India, with farmers also using Indian brands of colas.
The practice of using soft drinks in lieu of pesticides, which are 10 times more expensive, is gaining so much popularity that sales of the drinks have increased drastically in remote villages.
Farmers say the use of pesticides costs them 70 rupees ($1.50) an acre.
By comparison, if they mix a bottle of Pepsi or Coke with water and spray it on the crop it costs 55-60 rupees less per acre.

Old practice

Agricultural specialist Devendra Sharma says farmers are mistaken in thinking that the drinks are the same as pesticides.
He says the drinks are effectively sugar syrups and when they are poured on crops they attract ants which in turn feed on the larva of insects.
Mr Sharma says using sugar syrup for pest control is not a new practice.
"Jaggery made from sugar cane has been used commonly for pest control on many occasions. Pepsi and Coca-Cola are being used to achieve the same result," he says.
Fearless researchers nail two big, bad American multinationals selling toxic soda to India's masses? Get Bollywood on the line! Unfortunately for Coca-Cola (KO) and PepsiCo (PEP), this scenario isn't a film pitch. An anti-corporate lynch mob has pursued the pair of soda makers since Aug. 9, when a New Delhi environmental group released data purporting to show their soft drinks contain levels of pesticides that greatly exceed proposed Indian safety standards. In response, several Indian states banned sales of Coke and Pepsi.

If the companies have been negligent, of course, they deserve to be punished. But so far it appears that they have been singled out because they are foreign-owned. No Indian soft drink makers have been tested for similar violations, even though many people believe that pesticide levels are even higher in Indian-made milk and bottled tea. And while pesticide residues are present in virtually all groundwater in India, New Delhi has largely ignored the problem. "We are continuously challenged because of who we are," says Atul Singh, CEO of Coca-Cola India.
It's true: Farmers there have discovered that Coke and Pepsi are low-cost pesticides that, when sprayed on crops, deter insects quite effectively.

As this video clip shows, that may be because sodas in India have, from time to time, been found to contain alarmingly-high levels of pesticides due to local water contamination (Coke and Pepsi are always bottled locally, using the local water).
Or perhaps there's something else in the sodas that deters pests. Phosphoric acid, for example, is highly acidic and may function as a pest deterrent. Or perhaps it's the aspartame in the diet soda. Since aspartame as well known to promote neurological side effects in humans, it is conceivable that it may function as a neurotoxic pesticide when sprayed on crops.

Source