Movement of adult moths during each generation will influence the area and magnitude of this neighborhood effect. Conceivably, planting non-B.t. corn near B.t. Indirect benefits may also occur through decreased incidence of corn disease. Thus, stem rots and ear rots could be reduced along with mycotoxin production. Insects are known for their ability to rapidly develop resistance to certain insecticides.
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.