Findings from a newly completed AHDB-funded project suggest the decision to stop tomato growers using two non-native species of bumblebees for pollinating crops in unscreened glasshouses should be reviewed.
The decision, implemented by Natural England and Defra in 2015, has meant growers switching to the British native sub-species Bombus terrestris audax, which most have found has led to reduced fruit set, particularly in small-fruited varieties in hot weather.
Over the course of the project the research team concluded there was insufficient reliable and consistent evidence to support claims that the use of non-native bumblebees was harmful to wild populations of B. terrestris in the UK, on which the policymakers’ had based their change to the licensing regulations.
Molecular studies by the researchers – led by entomologist Rob Jacobson and Warwick associate professor Dave Chandler – suggest that bee sub-species originating from Britain, and labelled as B.t. audax, and those from mainland Europe (B.t. terrestris) are not separate, ‘pure’ genetic entities, but populations with some genetic groups in common.
‘This would support the idea that there is already some natural genetic mixing/interaction between populations in Britain and mainland Europe,’ said the report.
It added: ‘A meeting has been requested to present the new evidence to Natural England and Defra.’
Results from practical studies as part of the project suggest most B.t. audax colonies went into decline soon after being introduced to tomato crops and that there was also considerably less flight activity in the glasshouse environment compared to outdoors.