New in vitro larval test

Bt maize pollen has no effect on bee larvae

Scientists at the University of Würzburg’s Department of Animal Ecology and Tropical Biology have for the first time investigated how well honeybee larvae cope with Bt maize pollen under controlled laboratory conditions. Pollen from Bt maize MON810 and from a Bt maize variety that produces three different Bt proteins was not found to have any harmful effect on the larval stages of the bees. The larval test is part of a biological safety research project funded by the German Federal Ministry of Education and Research (BMBF).

Dr Stephan Härtel from the Department of Animal Ecology and Tropical Biology at the University of Würzburg is leading the research on genetically modified Bt maize.

Since it is difficult to raise bees in the laboratory, the Würzburg researchers developed a test system for moving newly emerged larvae directly from the beehive to the climate chamber without disturbing them.

Bt proteins mainly affect the larval stages of insects. In order to test how well bee larvae cope with Bt maize pollen, each group of 20 bee larvae was given maize pollen from one of five maize varieties, including two types of Bt maize. The larvae were given two milligrams of pollen, which is the amount of pollen found in the gut of bee larvae when bee colonies were kept in flight tents where they could only collect maize pollen.

All larvae that received Bt maize pollen survived until pupation. Even the combined Bt proteins, which are found in much greater concentrations in pollen than the Bt protein produced by MON810 maize, evidently pose no risk to honeybees, according to the results of this study. The survival rate of bee larvae fed on pollen from the conventional maize varieties was slightly lower.

The Würzburg scientists recommend that the test they developed be used as a standard method for assessing the risk of GM plants and also of crop protection products, which are present in all parts of a plant and therefore also in the pollen.

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Photo material

Bee larva with maize pollen diet

Bee larva with maize pollen diet

Source: Stephan Härtel /

Honey bee gather maize pollen

Honey bee gather maize pollen

Source: Stephan Härtel/