The paper published in the journal Biological Control reports that Bt crops have been grown on more than 1 billion acres over the last 20+ years, and on 100 million hectares in 2017 alone. A major concern related to this technology is that the proteins could harm non-target organisms, specifically those that provide important ecosystem services such as biological control. However, studies have proven that proteins from Bt crops did not harm natural enemies. Furthermore, Bt crops support the conservation of natural enemies and contribute to more effective biological control of both target and secondary pests and lead to a reduction in insecticide use.
The paper concludes that the efficacy of Bt crops in controlling important target pests has been very high. The large-scale adoption of Bt crops in some parts of the world has led to area-wide suppressions of target pest populations that benefited both the farmers that adopted the technology and those that did not.
For more details, read the paper in Biological Control.