Did anyone see the Thanet Earth tomato growing mega-complex on the BBC series ‘Harvest’ back in the autumn? In large greenhouses, the total Thanet site covers a gargantuan 220 acres (see it here) and produces 225 million tomatoes a year, there isn’t enough air movement for the male pollen to be shaken loose so that it falls on the female stigma and successfully pollinates the tomato. Bumble bees are raised in Europe and imported to provide this service.
Bumble bees hang upside down on the stamen and their flight muscles create the vibration that releases the pollen. Tomatoes don’t produce any nectar so the bees are fed sugar for the carbohydrate portion of their diet. The pollen provides their protein.
These colonies die out at the end of the season. New brood will be reared in a sterile factory by feeding the bumble bees pollen from honey bee colonies. Recently honey bee diseases such as deformed wing virus and Nosema ceranae, the fungal parasite related to dysentery-like symptoms, have been found in such bumble bees.
Introducing new species and their pathogens doesn’t have a good history. From cane toad plagues in Australia to the various diseases that decimated Amerindian populations when brought by the Spanish invaders, there is always an acclimatization period as resistance to the ‘invader’ is developed. As Dave Goulson puts in his definitive book on the bumble bee:
“Taking bees reared at high density and then shipping them thousands of miles to places where the bees themselves and any diseases they might be carrying do not naturally occur is an incredibly risky strategy. In fact, if one wished to spread diseases indiscriminately around the globe it would be hard to come up with a better system.”
The answer? Recommending IPM (integrated pest management). But isn’t that shutting the door after the horse has bolted?
To identify common UK bumble bees click here