Environmental risk assessment of the Cry1B.34.1, Cry1B.61.1, and IPD083Cb proteins to non-target organisms.

Abstract

Lepidopteran pests are a serious threat to soybean production worldwide and have developed resistance to several pest management options, including the use of transgenic soybean expressing crystalline (Cry) proteins derived from the soil bacterium Bacillus thuringiensis Berliner (Bt). For this reason, there is great interest in discovering insecticidal proteins that function via new modes and/or sites of action against lepidopteran pests to support a sustainable and durable management plan. Event COR-23134-4 (hereafter referred to as COR23134 soybean), which expresses Bt-derived insecticidal proteins Cry1B.34.1 and Cry1B.61.1 and a novel plant-derived IPD083Cb insecticidal protein, was developed to provide additional sites of action to confer protection against certain susceptible lepidopteran pests. As part of the environmental safety assessment, the potential risks (exposure and hazard) posed by the cultivation of COR23134 soybean to non-target organisms (NTOs) were assessed. The environmental risk was characterized by comparing the Tier I laboratory hazard study results to worst-case or refined estimated environmental concentrations (EECs) to establish the margin of exposure (MOE) for the Cry1B.34.1, Cry1B.61.1, and IPD083Cb proteins in COR23134 soybean. Overall, results from the exposure and hazard assessments and the MOE values show that the Cry1B.34.1, Cry1B.61.1, and IPD083Cb insecticidal proteins expressed in COR23134 soybean are not expected to result in unreasonable adverse effects on NTO populations at environmentally realistic concentrations; hence, the risk to NTOs from the cultivation of COR23134 soybean is considered negligible.