Natural England withdrew the license to release non-native subspecies B.t. terrestris and B.t. dalmatinus in unscreened glasshouses in 2014. Since then, UK tomato growers have reported poor pollination performance from the native Bombus terrestris audax.
A previous survey by the British Tomato Growers Association at the end of 2015 suggested that the native bumblebee was performing less well than the non-native subspecies. So poor were some of the results that several growers said they had reverted to the labour-intensive manual methods of pollination they had not had to use for 25 years.
Those who had achieved adequate levels of pollination had done so only by using more hives than had normally been needed for the other subspecies.
If inadequate pollination resulted in the loss of fruit set on just two trusses per plant, it’s calculated that it could be costing growers as much as £45,000 per ha per season.
The survey is being conducted as part of AHDB project PE 032 and the results are expected in autumn 2017.