Resistance occurs particularly when insecticides are used repeatedly and at high concentrations. More than 500 species of insects and mites have developed resistance to insecticides. A recent Midwestern example in corn includes adult western corn rootworm resistance to Penncap-M in Nebraska. In addition, laboratory colonies of more than 15 different insect pests have developed resistance to B.t. proteins, including Indian meal moth, tobacco budworm, beet armyworm, pink bollworm and Colorado potato beetle. Moreover, the diamondback moth, a worldwide pest of cole crops, has developed high levels of resistance to B.t.
Many factors contribute to the development of resistance.
This modest level of B.t. Although these results confirm the genetic potential of European corn borer to develop resistance, laboratory studies do not prove resistance will develop under field conditions. Scenarios of resistance development by European corn borer are suggested by studies of insecticide resistance in many insects and by resistance to B.t. Resistance genes are likely to be rare. As the B.t.