http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0059589
Abstract
Honey bee pollination is a key ecosystem service to nature and agriculture.
However, biosafety research on genetically modified crops rarely considers
effects on nurse bees from intact colonies, even though they receive and
primarily process the largest amount of pollen. The objective of this study
was to analyze the response of nurse bees and their gut bacteria to pollen
from Bt maize expressing three different insecticidal Cry proteins
(Cry1A.105, Cry2Ab2, and Cry3Bb1). Naturally Cry proteins are produced by
bacteria (*Bacillus thuringiensis*). Colonies of *Apis mellifera carnica* were
kept during anthesis in flight cages on field plots with the Bt maize, two
different conventionally bred maize varieties, and without cages, 1-km
outside of the experimental maize field to allow *ad libitum* foraging to
mixed pollen sources. During their 10-days life span, the consumption of Bt
maize pollen had no effect on their survival rate, body weight and rates of
pollen digestion compared to the conventional maize varieties. As indicated
by ELISA-quantification of Cry1A.105 and Cry3Bb1, more than 98% of the
recombinant proteins were degraded. Bacterial population sizes in the gut
were not affected by the genetic modification. Bt-maize, conventional
varieties and mixed pollen sources selected for significantly different
bacterial communities which were, however, composed of the same dominant
members, including *Proteobacteria* in the midgut and *Lactobacillus* sp.
and *Bifidobacterium* sp. in the hindgut. Surprisingly, Cry proteins from
natural sources, most likely *B. thuringiensis*, were detected in bees with
no exposure to Bt maize. The natural occurrence of Cry proteins and the
lack of detectable effects on nurse bees and their gut bacteria give no
indication for harmful effects of this Bt maize on nurse honey bees.
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