The insects that ingest the Bt and later die from it, are not considered dangerous to birds or other animals that may feed on the dead insect. Bt is not known to cause injury to plants on which it has been applied and is not considered harmful to the environment. Little or no resistance has been reported to date, but one still should be cautioned against the over use of Bt. Relying on any one pesticide can lead to the build up of resistance in the pest population. Use of other insecticides and cultural control methods should be used to slow down or eliminate the possibility of resistance developing.
Microbial insecticides are more expensive to produce than chemical insecticides.
Microbial insecticides are more environmentally benign, selective, and cause minimal impacts on non-target organisms. Microbial insecticides are less expensive to register than chemical insecticides. Microbial insecticides are more difficult to apply in the field, are less persistent, and are slower acting than many chemical control agents. Microbial insecticides are compatible with integrated pest management practices. Transgenic plants and other microorganisms.