Insecticides
Substances which are used to kill insects are called insecticides. Insecticides have a wide application in the field of medicine, agriculture, and industry.
Types of insecticides
- There are three different types of insecticides.
Systemic
- This type of insecticide is introduced into the soil for it to get absorbed by the plant roots.
- Once the insecticide enters the roots, it moves to external areas such as leaves, fruits, twigs, and branches.
- It forms a layer on the plant surface area and acts as a poison to any insect that comes to chew the plant.
Ingested
- Some examples of ingested pesticides are rat and roach.
Contact
- These types of insecticides act like bullets that aim only at a particular target to kill insects by its application.
- Usually, household insect spray works like contact insecticides as it must directly hit the insect.
Disadvantages of insecticides
Non-target organisms
- Insecticides can kill more than intended organisms and are risky to humans.
- When insecticides mix with water sources through leaching, drift, or run off, they harm aquatic wildlife.
- When birds drink such contaminated water and eat affected insects, they die.
- Some examples of insecticides, like DDT, were banned in the US as it affects the reproductive abilities of predatory birds.
Resistance
- Insects when repeatedly exposed to insecticides build up resistance until finally, they have little or no effect at all.
- The reproduction in insects is so quick that they produce a new generation every three to four weeks.
- Therefore, the resistance builds up rapidly.