Difficulties with this approach are the identification of sources of resistance and the long term duration of this resistance, as insects adapt and evolve to overcome resistance in the plant. Chemical controls, including a wide array of synthetic chemical insecticides Insecticides are very widely used and can be extremely effective. However, there are a number of concerns and limitations regarding the use of insecticides as outlined below. Insecticides are in many cases short lived on the plant, therefore requiring repeated applications of the pesticide. Insecticides may have difficulty reaching the site where the target insect feeds on the plant, unless the insecticide is taken up by and spread systemically through the plant.
Insecticides can kill both target pests and non-pest beneficial insects.
Insects develop resistance to insecticides, reducing or eliminating their effectiveness. There are significant concerns about the safety of insecticides, their effect on the environment, contamination of groundwater, etc. There is certainly room to improve the current control practices, including greater use of IPM, incorporation of more resistance genes into crops, and development of insecticides that have less impact on the environment and are safer. In addition, gene transfer affords some new opportunities to control insect pests. In many cases the attack takes the form of female insects laying their eggs in the seed.