Effect of Bt toxin Cry1Ab on two freshwater caddisfly shredders – an attempt to establish dose-effect relationships through food-spiking

Abstract

Genetically modified organisms (GMOs), which produce Bacillus thuringiensis (Bt) toxins, are widely used in agriculture in some parts of the world. Despite this, ecotoxicological methods, tailored to GMOs, are lacking to assess effects on aquatic environments. With the objective to investigate a foodrelated exposure pathway for aquatic shredders, we used a new food-spiking method while caddisfly larvae (Chaetopteryx spec., Sericostoma spec.) served as test species. Pure Cry1Ab toxins were spiked on black alder leaf discs and subsequently used in a feeding experiment. The toxin did not influence larval mortality compared to the control. The results, however, showed significant effects on larval lipid content (Chaetopteryx spec.) and development (Sericostoma spec.) at concentrations of 17.2 and 132.4 ng Cry1Ab/mg leaf, respectively. These changes are indicative for impacts on the fitness of the specimen and thus relevant in a risk assessment context. Ultimately, the food-spiking method allowed applying different Bt toxin concentrations leading to the establishment of dose-response relationships for various response variables. The use of long test durations and sublethal endpoints (consumption, lipid content, growth, larval instars) is, moreover, advisable when testing GMO effects.

Fate of Environmental Proteins (eProteins) from Genetically Engineered Crops in Streams is Controlled by Water pH and Ecosystem Metabolism

“…This was a consequence of the slower second phase of degradation, which happens roughly at the same rate as DOC. Nonetheless, documented nontarget impacts of Bt-Cry happen at chronic exposure , or at concentrations many orders of magnitude higher than the persistent ones . Thus, the downstream concentrations of Cry protein are likely to be diluted, but upstream regions that are near direct inputs may be where concentrations are highest, and where the impact of Cry proteins should be closely monitored. , However, as Bt maize detritus travels downstream in the watershed and leaches the protein along the way for several days, the predicted range of impact may increase, as higher protein concentrations could be observed downstream if there is a traveling source. , Accordingly, management techniques that stop detritus from entering waterways, such as protection of riparian vegetation and buffer strips along field edges, may be highly effective in limiting the input and impact of Cry protein to adjacent aquatic ecosystems, especially at the local scale.…”

“…Despite its specificity, some studies have shown potential impacts of Cry protein on nontarget aquatic organisms such as caddisfly larvae (Trichoptera) chronically exposed to the protein , or zooplankton exposed to acute doses of 750 000 ng/L . By negatively influencing larval caddisfly growth rates and consequentially their fitness, this eProtein can potentially alter food webs in aquatic ecosystems .…”

Assessment of the 2018 post‐market environmental monitoring report on the cultivation of genetically modified maize MON 810 in the EU

“…EFSA identified two additional relevant publications, Bertho et al (2020) and Pott et al (2020), which were published after the period covered by the literature search performed by the consent holder.…”

“…Publication by Pott et al (2020) This publication addresses the effect of the Cry1Ab protein on two freshwater caddisfly (Trichoptera) shredders under environmentally controlled (laboratory) conditions. The results reported by the authors do not provide any new information that would invalidate the previous safety assessment conclusions and risk management recommendations on maize MON 810 made by EFSA or its GMO Panel (for further details on the assessment, see Annex 4 of supporting information).…”

“…() and Pott et al. (), which were published after the period covered by the literature search performed by the consent holder.…”