The University of Stirling has suggested that some of the world's most commonly used pesticides are killing bees by damaging their ability to navigate and reducing the number of queens.
The UK team believes the pesticides caused an 85 per cent drop in queen production, which reduces crop yields. In the UK, pollination is calculated to be worth £430m to the economy.
The neonicotinoids investigated in the two Science journal papers are used on crops such as cereals, oilseed rape and sunflowers.
Meanwhile, an investigation by the French Institute for Agricultural Research has suggested that the number of bees able to make it back to the colony after release was significantly fewer if they had previously been exposed to levels of thiamethoxam they might encounter on farms.
A Defra representative said: "We review the science regularly. If any new evidence shows the need for action, we will not hesitate to act. We are aware that the EU authorities are also looking at these issues and will contribute actively to that process.
"However, the UK has a robust system for assessing risks from pesticides. The substantial evidence already gathered supports the conclusion that neonicotinoids do not pose an unacceptable risk to honey bees."