Will genetically engineered crops increase the need for insecticides?

No. At worst, the insects controlled by the genetic traits in the GE crops will develop resistance in time, necessitating the return to the same amount of insecticide used before the advent of the GE crops. This is unlikely, though, since the makers of insecticides are continually improving them to be less toxic to non-target species, more environmentally friendly, and require a smaller dose. There are already some insecticides which require less than two ounces per acre for effective suppression of the target species. Compare this to some older formulations which required as much as three gallons per acre.