GMOs usually need far fewer pesticides sprayed on them, that is pretty much the point of them most of the time.
This depends entirely on the modification. The two most popular GMOs are "roundup ready" and "Bt." Roundup-ready plants are resistant to glyphosate, which allows farmers to use higher amounts of the herbicide. "Bt" plants produce their own insecticide, which allows farmers to reduce their external application of such agents. As glyphosate resistance transfers to weed plants, biotech companies have begun developing resistance to other herbicides: the next step in the evolutionary arms race.