An alternative method of pest control is introducing predatory insects. The predatory insects eat the pest insects. This method can be effective, but it is very time sensitive. If the predatory insects are not released during the currect stage of pest developement, then they fail to protect the crop. Crop rotation can also reduce the need for pesticide application.
Horticultural oils can kill insects by smothering their pores.
They are considered safe for humans and leave very minimal residue. I do not know if they are cost effective for large scale farming practices. The EPA, which is supposed to regulate and approve new pesticides is actually helping to slow down the introduction of newer safer pesticides. Older pesticides have been okayed for use, but newer, safer, and more effective pesticides are denied permits because they cannot meet the EPA's strict guidelines. I guess the EPA considers it no big deal that we are still using older more dangerous pesticides while better ones sit unused.