According to lead author, Michele Marvier, of Santa Clara University, ”We can now answer the question: Do Bt crops have effects on beneficial insects and worms? The answer is that it depends to a large degree upon the type of comparison one makes. When Bt crops are compared to crops sprayed with insecticides, the Bt crops come out looking quite good. But when Bt crops are compared to crops without insecticides, there are reductions of certain animal groups that warrant further investigation.”