Insecticides are of chemical and biological origins and are used in agriculture, forestry, gardens, homes, and offices. They are also used to control vectors, such as mosquitoes and ticks, that are involved in spreading human and animal diseases [3]
The synthetic contact insecticides are now the primary agents of insect control. In general, they penetrate insects readily and are toxic to a wide range of species.[1] The main synthetic groups are the chlorinated hydrocarbons, organic phosphates (organophosphates), carbamates, pyrethroids, neonicotinoids.
1. Chlorinated hydrocarbons
They were commonly used earlier, but now many countries have been removed Organochlorine insecticides from their market due to their health and environmental effects and their persistence. Representative members of this insecticide class include DDT, methoxychlor, aldrin, dieldrin, heptachlor, chlordane, lindane, BHC, and chlorobenzilate [1].
Advantages
- The chlorinated hydrocarbons are very potent nerve toxins to insects, and their initial use led to significant improvements in insect control.
Disadvantages
- These compounds have a long residual action in the environment so they have been banned in most countries in the past 30 years[3].
2. Organophosphates
Two widely used compounds in this class are parathion and malathion; others are fenthion, fenitrothion, diazinon, naled, methyl parathion, and dichlorvos
Advantages
- They are especially effective against sucking insects such as aphids and mites, which feed on plant juices
- They usually have little residual action in the environment
Disadvantages
- They have a far greater acute toxicity in mammals and have an unpleasant odor.
3. Carbamates
The carbamates are a group of insecticides that includes such compounds as carbamyl, carbaryl methomyl, propoxur, and carbofuran. carbaryl has been used most widely in home and garden applications.
Advantages
- They usually have little residual action in the environment and have a high insecticidal effect.
Disadvantages
- These compounds also have a far greater acute toxicity in mammals
4.Pyrethroids
The most important commercially available pyrethroids are allethrin, bifenthrin, cyfluthrin, lambda-cyhalothrin, cypermethrin, deltamethrin, permethrin, d-phenothrin, resmethrin, and tetramethrin [3].
Advantages
- Pyrethroids have high toxic action on insects but low mammalian toxicity.
- They break down quite rapidly in the environment following application.
Disadvantages
- Their use is still limited by their environmental liability, relatively high cost, and their tendency to lose effectiveness through the development of insect resistance.
5. Neonicotinoids [2],[4],[5]
The neonicotinoid insecticides include imidacloprid, acetamiprid, dinotefuran, thiamethoxam, and clothianidin. Imidacloprid is the most widely used insecticide in the world.
Advantages
- Neonicotinoids are new classes of insecticides that are applied at low dosages and are extremely effective but are relatively nontoxic to humans.
Disadvantages
- These insecticides can be toxic to beneficial insects such as honey bees
Benefits of Insecticides
- Controlling human/livestock disease vectors and nuisance organisms.
- Controlling organisms that harm other human activities and structures.
Effects of Insecticides
- The toxic chemicals in these are designed to deliberately release into the environment. Though each insecticide is meant to kill a certain insect, a very large percentage of insecticide reaches a destination other than their target. Instead, they enter the air, water, sediments, and even end up in our food.
- Insecticides have been linked with human health hazards, from short-term impacts such as headaches and nausea to chronic impacts like cancer, reproductive harm.
References
- https://www.britannica.com/technology/insecticide
- https://www.revealnews.org/article-legacy/5-pesticides-used-in-us-are-banned-in-other-countries/
- https://www.sciencedirect.com/topics/medicine-and-dentistry/insecticide
- https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/neonicotinoid
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5533829/
5.884 - 12/08/201909:18' SA
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