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There is a variety of insecticides for different purposes available in the market today. However, what is insecticide? An insecticide is a chemical or biologically formulated substance used to mitigate, repel, kill or harm several species of insects. This chemical or man-made substance work to either damage an insect’s exoskeleton or destroy their nervous system, while others control or kill them through other ways. So, how do insecticides work?
Insecticides can either be larvicides, ovicides, adulticides which are used to kill larvae, eggs, and adult insects, respectively. Insecticides have proven to increase agricultural productivity and healthy against vectors.
You can read about the most efficient insecticides on the market here. They are used within the household, medicine, agriculture, and industry. What are the types of insecticides? Keep scrolling to learn more.
Types of Insecticide
There are two types of insecticides, natural and chemical based. The following are examples of insecticide;
Natural oils and fatty acids derived from plants and animals can be used as organic insecticides. They are sustainable and are not harmful to crops. These natural and homemade insecticides include;
• Oil spray: Neem oil has been used for years to ward off pests.
• Citrus oil and Cayenne Pepper: mixing ten drops of citrus essential oil with a teaspoon of cayenne pepper and 1 cup of warm water in a spray bottle is a powerful and organic pesticide.
• Eucalyptus oil
• Onion and garlic spray: mix one glove of minced garlic and one medium sized organic onion with a quart of water. Add a tablespoon of cayenne pepper and one tablespoon of a liquid dishwasher for a potent and organic spray.
• Tobacco is harmful to humans and pests. It makes a powerful and natural insecticide.
• Mineral oil works by dehydrating insects and their eggs.
• Chrysanthemum Flower tea: this is a plant that contains pyrethrum which invades the nervous system of insects causing them to be immobile.
Chemical insecticide is either man-made or synthetic based from formulas like carbonate or pyrethroids. Inorganic insecticides are created from heavy metals and arsenic compounds like boric acid and silica gel. They are effective in killing pests but must be used with guidance. Inorganic insecticides include;
• Systemic Insecticide: These are insecticides for trees. It is planted in the soil and is soaked in by the root of plants. The absorbed insecticide moves into the leaves, branches, fruits, and twigs of the plant and protects it from destruction from pests. Like most transportable chemicals, systemic insecticides take place in the plants vascular system, more specifically the phloem and xylem.
• Contact Insecticides: these come in the form of liquid vaporizers, repellents, sprays, coils, insecticide spray, and granular systemic insecticide, are used to kill and eradicate insects and mosquitoes. They can also work as disinfectants and deodorizers in the home.
• Ingested insecticides: An example of this is Rodenticide used to kill rats. Ingested insecticides also kill rodents and cockroaches.
• Herbicides: these are used to kill infected plants, it kills off the parts of the plant that insects feed on or the infected parts of the plants.
Insecticides aerosols are sprays that have active pesticides and other minor ingredients that kill or immobilize insects. Aerosols are metered which means they produce less waste and each spray releases a specific amount of poison. There are three main types of aerosols, these are contact, residual and insect growth regulator (IGR) sprays, while some other products have all 3 in 1.
Contact Insecticide Aerosols: These sprays are sprayed directly onto the target insect. They contain pyrethroid and other active ingredients that target the nervous system of the insect. Most contact sprays do not eliminate eggs, which means the insect cycle can continue. Insects like bed bugs can build a resistance to the active chemical in contact sprays, and a stronger chemical will be required.
Residual Insecticide Aerosols: These are applied to surfaces to kill bugs and insects and remain active for a more extended period of time.
Insect Insecticide Aerosols: This renders the insects sterile and disrupts their breeding and lifecycle.
Insecticide vs. Pesticide
Most people use pesticide and insecticide interchangeably, which is wrong. They have connected, but not identical uses, and both must be used with caution.
Insecticides are a sub-category of pesticides formulated especially for insects. It is used to kill adult insects or larvae and is found in most mosquito killer sprays. Insecticides work by stopping the life cycle of insects by destroying their reproductive systems.
Hence, when the adults die, no new insects are produced. Insecticides can be used in agriculture and are also often used as household insecticide sprays to kill household pests. It can be packaged in the form of gels, baits, sprays, dust, and coils.
Insecticides fall into six general groups;
Organophosphates (OP): This includes Chlorpyrifos and malathion which are used for interfering with the transmission of nerve impulses in insects. They attack the synapses, which is the tiny gap between one nerve fiber and the next. One of the most common neurotransmitters is acetylcholine, and the enzyme that breaks it down is acetylcholinesterase. OP insecticides inhibit the action of the enzyme, causing uncoordinated movements, tremors, and convulsion.
Carbamates: Example of this includes carbaryl, bendiocarb, and propoxur. These act as cholinesterase inhibitors and when insects are exposed to them, they exhibit similar symptoms like with OP.
Pyrethroids: Examples of this includes permethrin, cypermethrin, fenvalerate, and cyfluthrin. This interrupts the normal transmission of nerve impulses by affecting the potassium or sodium ion channel in nerve cells.
Insect Growth Regulators (IGR): Examples of this include methoprene and pyriproxyfen. These affect insects by killing them before they become full adults or pupa. It affects immature insects by targeting the hormones that control molting in insects. This type is generally safe for humans since we do not possess these insect hormones.
Chlorinated hydrocarbons: such as methoxychlor and dicofol disrupt the movement of potassium and sodium ions in nerve cells surfaces. It inhibits normal nerve cell function and causes symptoms similar to OP and carbamate.
Microbial insecticides: It is made from microorganisms to eliminate insects. It attacks the cuticle and cells of insects and is safe for humans.
Pesticides are essentially insecticides for plants. They come in different forms and are a broader category for killing and eliminating pests on plants. Most pesticides are insecticides and are used for landscapes or agriculture. These pesticides include;
• Algaecides are used for killing or slowing the growth of algae
• Antimicrobials are used for controlling germs and microorganisms like bacteria and viruses.
• Desiccants are used to dry living plant tissue
• Disinfectants are used to control germs and microorganisms like bacteria and viruses
• Fungicides are used to control fungal problems like molds, rust, and mildew
• Miticides are used for controlling mites that destroy plants and animals.
• Mothballs are used to kill fabric pests
• Herbicides kill or stop the growth of unwanted plants known as weeds.
Insecticides can be characterized by their range of coverage. They can either be narrow spectrum or broad-spectrum insecticides. The spectrum is based on the variety of organisms and size of pests affected.
Narrow Spectrum Insecticides
Insecticides that cover a small coverage range are known as narrow-spectrum insecticides. This is because they are designed to control or kill a specific group of organisms that cause damage.
They are specifically designed to attack a characteristic of the pest that is known to that organism, for example, pheromone, hormone or physical features.
Chitin inhibitors are an example of narrow-spectrum insecticides. The chemicals interact with chitin, a part of the exoskeleton in insects. It stops the development of chitin and kills the insect eventually. Chemicals that interact with chitin will only affect insects that have an exoskeleton and will not harm other insects.
In extreme situations, targeting specific species of organisms might not be efficient. A broad-spectrum insecticide targets a larger species of organisms and pests that are causing harm to plants and crops. It is usually employed when a variety of different species is causing damage, which is why it is also known as a non-selective pesticide.
To achieve killing a wide species of organisms, broad-spectrum possess a chemical that targets a system or characteristic common in many organisms like the muscular system or nervous system.
A common broad-spectrum insecticide is methyl bromide, used to in eliminating and controlling large rodents and weeds.
It also removes pathogens, insects and other pests that destroy crops. It is usually injected into the soil, and in other instances, it is pumped into barns or warehouse to eliminate pests that are harmful to plants in storage.
Unlike the controlled feature of narrow spectrum pesticide, the broad spectrum can be toxic to harmless and helpful insects like bees and other pollinators. Most organic farmers do not use broad-spectrum insecticide. Most organic farmers do not use them because they strive to grow healthy and organic crops that are chemical-free.
Brodifacoum, a rodenticide, is a form of broad-spectrum pesticide that is injurious and toxic to dogs that accidentally ingest it. Other types of broad-spectrum insecticide include neonicotinoid, organophosphate, pyrethroid, and carbamate insecticides are used for commercial purposes while chlorpyrifos can be used in targeting a select group of pests when used in moderation.