The study, carried out by researchers at the University of Calcutta, found a disturbing trend in the growth of yields of several vegetables despite an increase in their cultivation area over the past 45 years.
Led by Parthiba Basu, a researcher at the varsity's Ecology Research Unit, the team analysed the growth of yield and cultivated area of 11 major pollinator-dependent vegetable crops, including cucumbers, brinjals, pumpkins, tomatoes and gourds, between 1963 and 2008.
Basu and his student Ritam Bhattacharya presented their findings at a recent British Ecological Society meeting held at the University of Leeds.
It was found that although the area used for cultivating those vegetables has gone up by 340 per cent (over six times), their absolute yield has increased by a meagre 63 per cent taking 1963 as the base year.
However, pollinator-independent vegetables like potatoes, ginger, garlic and several pulses have witnessed a proportionate increase in their yields compared to their cultivation area during this period.
"This is an indication that yields of pollinator dependent crops might be affected by the pollinator loss as during the same period, the non pollinator dependent crops have shown increase in the yields," said Dr Basu.
"There is hence both a dependence and crisis. Of the crops mentioned above, brinjal and tomatoes have shown a steady increase in cultivated area and hence have become both increasingly dependent on pollinators as well as been hit by a seeming pollinator crisis," he told PTI.
"The findings that a shrinking yield of pollinator- dependent crops would indicate pollinator limitation, while an expanding area under these crops would indicate an increased dependence on pollinators."
Pollination is a natural process in which pollen is transferred by pollinators such as bees and butterflies in plants, enabling their fertilisation and reproduction.
If the findings are extrapolated, Basu said, this would offer a "clear indication" that India is facing a decline in natural pollinators, as ecological farming is practiced on only about 10-20 per cent of the country's arable land.
"Overuse of pesticides and vanishing wilderness areas from our agricultural landscape could be the main reasons behind the decline in natural pollinators," Dr Basu said.
India produces 71 million tonnes of some 70-odd varieties of vegetables annually, accounting for about 14 per cent of the global vegetable production.
According to Basu, there is hardly any data available that allows one to compare natural pollinator populations -- bees and butterflies -- across years, which forced them to compare the yields of pollinator-dependent crops with the crops that don't depend on natural pollinators.
He also said they have taken up a study in West Bengal and the early results confirm that there is significantly higher pollinator abundance and higher yields in ecological farms as compared to conventional farms.
"We are now initiating an exercise to collect such data from other parts of the country too as a coordinated initiative," he said.
However, the scientist denied that the pollinator crisis would lead to a food crisis in the country in coming years.
"If there is a pollination crisis, it is not going to affect India's food security as there are several cereal crops that are not pollinator dependent. What is going to be affected is nutritional security," Basu said.