Abstract
Despite their importance as pollinators in crops and wild plants, solitary bees have not previously been included in non-target testing of insect-resistant transgenic crop plants. Larvae of many solitary bees feed almost exclusively on pollen and thus could be highly exposed to transgene products expressed in the pollen. The potential effects of pollen from oilseed rape expressing the cysteine protease inhibitor oryzacystatin-1 (OC-1) were investigated on larvae of the solitary bee Osmia bicornis ( = O. rufa). Furthermore, recombinant OC-1 (rOC-1), the Bt toxin Cry1Ab and the snowdrop lectin Galanthus nivalis agglutinin (GNA) were evaluated for effects on the life history parameters of this important pollinator. Pollen provisions from transgenic OC-1 oilseed rape did not affect overall development. Similarly, high doses of rOC-1 and Cry1Ab as well as a low dose of GNA failed to cause any significant effects. However, a high dose of GNA (0.1%) in the larval diet resulted in significantly increased development time and reduced efficiency in conversion of pollen food into larval body weight. Our results suggest that OC-1 and Cry1Ab expressing transgenic crops would pose a negligible risk for O. bicornis larvae, whereas GNA expressing plants could cause detrimental effects, but only if bees were exposed to high levels of the protein. The described bioassay with bee brood is not only suitable for early tier non-target tests of transgenic plants, but also has broader applicability to other crop protection products.
Highlights
Modified (GM) crops expressing proteins from Bacillus thuringiensis (Bt) are cultivated on a rapidly increasing acreage worldwide [1] since their commercialization in the mid 1990s, and, with the exception of cotton expressing both Bt and CpTI, are the only insectresistant Genetically modified (GM) plants to have been brought to the marketplace
Reagents OC-1 was prepared as a recombinant Escherichia coli-produced protein as previously described by Ferry et al [42] whilst lyophilized insecticidal d–endotoxin Cry1Ab was obtained from M
Mortality was unaffected across all treatments, sub-lethal effects were detected on larval development time and on the efficiency of converting pollen food into larval body mass when O. bicornis larvae were fed with 0.1% Galanthus nivalis agglutinin (GNA)
Summary
Modified (GM) crops expressing proteins from Bacillus thuringiensis (Bt) are cultivated on a rapidly increasing acreage worldwide [1] since their commercialization in the mid 1990s, and, with the exception of cotton expressing both Bt and CpTI (serine protease inhibitor from cowpea), are the only insectresistant GM plants to have been brought to the marketplace. Honey bees (Apis mellifera L.) are regarded as the most economically important pollinators of agricultural crops worldwide [5]. Solitary bees (both wild and managed) provide an important pollination service and their value for agriculture is increasingly being recognized [6,7,8]. This is true for areas and crops where honey bees are absent or are inefficient pollinators, and under these conditions non-Apis bees can substantially enhance production [9,10]. Several solitary bee species (mainly members of the genus Osmia) have been developed into manageable crop pollinators [11,12] and have often been found to contribute to higher crop yields than honey bees (e.g. [13])
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