Integrated Pest Manegment is one interpretation of this acronym. Some translate it as Intelligent Pest Management.
In either case, the idea is to use a variety of methods to deal with pests which reduce the use of chemicals. There are many legitimate reasons to take this approach, most important of which is to protect ourselves and the environment from materials which have limited usefulness for their intended purpose and long lasting affects in the environment.
The simple act of spraying water on plants to wash the pests off can go a long way for dealing with the problem without the use of any chemicals.
Before the development of many of our present pesticides, crop rotation worked very well to control some serious agricultural pests. Using cover crops which conserve soil and replenish nutrients provide added benefits in the reduction of some pests.