18 June 2013 | By James Rodger
An article in Farmers weekly on the use of bumblebees for applying pesticide to flowers stimulated a response from several South African scientists, including C·I·B researchers Dave Richardson, Steven Johnson and C·I·B PhD graduate James Rodger. Although the pesticide has not been approved for use in South Africa, the article said, quite incorrectly, that nothing stops South African farmers from using bumblebees for pollination in the meantime.
Bumblebees don’t occur in South Africa but the species featured in the article, the large earth bumblebee Bombus terrestris, which comes from Europe, is already an invasive species in many parts of the world. In South Africa we have carpenter bees (Xylocopa species) but not bumblebees, and although it is a common mistake to confuse the two, they are quite different. Importing any bees (in fact any insect) can only be done under permit.
It is often hard to prevent new outbreaks of invasive species because we don’t know in advance which of the species that we introduce are going to become invasive. What we do know, however, is that species that have already become invasive after introduction in one part of the world are very likely to become invasive if introduced elsewhere. The large earth bumblebee has been exported to many parts of the world to pollinate crops, especially greenhouse grown tomatoes, for which honeybees are not effective pollinators. It is now invasive in New Zealand, Tasmania, Japan, Chile, Argentina and Israel. This history of invasion means that if they are used for greenhouse pollination in South Africa, they will probably escape into the wild and become invasive here.
In the countries where it has invaded, large earth bumble bees have caused declines in native pollinators and improved the pollination (and therefore seed production) of invasive plants, some of which have only started to spread since its arrival. If these bees became invasive in South Africa, we would be very likely to have the same problems here. In fact, when an application was made to import bumblebees to South Africa a few years ago, it was turned down. Australia and the United States have also banned the import of large earth bumble bees because of their potential negative impacts. Despite this, we may see applications to import bumble bees in the future, and although a thorough risk assessment would probably recommend that the application be rejected again, the best solution may be to use indigenous bee species for pollination of crops that are not well served by honeybees. This approach has already borne fruit in Australia and North America, and must now be considered for South African bee species.
Read the articles
- Bumblebees fly to the rescue. Farmer’s Weekly. 12 April 2013
- SA should put bumblebees to flight. Farmer’s Weekly. 24 May 2013
For more information, contact James Roger at jgrodger@sun.ac.za