a. Development of resistance in insect: Continual exposure and intensity of pesticide induce the target pest to develop a resistance generation.
b. Outbreak of pest: Mass destruction of the natural enemies due to pesticide influence also creates a congenial environment for major and minor pest.
c. Hazard of pesticide residue: Depending on the inherent nature of the chemical build-up of a pesticide it depletes its toxicity in time. Before they given up their toxicity due to environmental weathering factors, these chemical lefts over persist becoming a potential hazard.
d. Environment Pollution: Residues of pesticides leftover on soil and other parts of plant remain in water, soil, air and mammal adipose tissues for a long time and may cause long lasting time.
e. Phytotoxicity: Depending on the nature of pesticides plants may be harmed because of chemical interactions among plants and pesticide. Burning spot on leaves, distorted leaves, restricted growth and other undesirable symptoms are seen in plants.
f. Adverse effect on non-target organism: Use of pesticide against target pests affects insect parasitoids and predators, honeybee, other pollinators and wildlife also, which cause the loss biodiversity. Repeated use of pesticides on crop has disruptive effects on beneficial insects like pollinators, bio-control agents, soil wild and aquatic life. Indiscriminate use of insecticides on the field crops has resulted in widespread mortality of honeybees and wild bees which are essential for pollination.
g. Resurgence of pest: Resurgence refers to an abnormal increase in pest population following insecticide application. Use of broad spectrum and persistent insecticide kill the natural enemies resulting into resurgence of insect pests. Sometimes, pesticides kill the key pests and under such condition secondary pests become the primary pests