How does pesticide kill insects

Skip to main content. Contact Us. Table 1. Usually broad-spectrum insecticides that have been taken out of use. Organophosphate Cause acetylcholinesterase AChE inhibition and accumulation of acetylcholine at neuromuscular junctions causing rapid twitching of voluntary muscles and eventually paralysis. A broad-range insecticide, generally the most toxic of all pesticides to vertebrates.

Organosulfur Exhibit ovicidal activity i. Used only against mites with very low toxicity to other organisms. Carbamates Cause acetylcholinesterase AChE inhibition leading to central nervous system effects i. Has very broad spectrum toxicity and is highly toxic to fish. Formamidines Inhibit the enzyme monoamine oxidase that degrades neurotransmitters causing an accumulation of these compounds; affected insects become quiescent and die.

Used in the control of OP and carbamate-resistant pests. Dinitrophenols Act by uncoupling or inhibiting oxidative phosphorylation preventing the formation of adenosine triphosphate ATP. All types have been withdrawn from use. Organotins Inhibit phosphorylation at the site of dinitrophenol uncoupling, preventing the formation of ATP. Used extensively against mites on fruit trees and formerly used as an antifouling agent and molluscacide; very toxic to aquatic life.

Pyrethroids Acts by keeping open the sodium channels in neuronal membranes affecting both the peripheral and central nervous systems causing a hyper-excitable state. Symptoms include tremors, incoordination, hyperactivity and paralysis. Effective against most agricultural insect pests; extremely toxic to fish.

Nicotinoids Act on the central nervous system causing irreversible blockage of the postsynaptic nicotinergic acetylcholine receptors. Used in the control of sucking insects, soil insects, whiteflies, termites, turf insects and the Colorado potato beetle. Generally have low toxicity to mammals, birds and fish. Spinosyns Acts by disrupting binding of acetylcholine in nicotinic acetylcholine receptors at the postsynaptic cell.

Effective against caterpillars, lepidopteran larvae, leaf miners, thrips and termites. Regarded for its high level of specificity. Effective against psylla, aphids, whitefly and thrips. Results of testing on one type fipronil indicate no effects on the clams, oysters or fish, with marginal effects on shrimp. Pyridazinones Interrupt mitochondrial electron transport at Site 1; mainly used as a miticide; display toxicity to aquatic arthropods and fish.

Quinazolines Acts on the larval stages of most insect by inhibiting or blocking the synthesis of chitin in the exoskeleton. Developing larvae exhibit rupture of the malformed cuticle or death by starvation; not registered in U.

Botanicals Depending upon the type can have various effects: Pyrethrum — affects both the central and peripheral nervous systems, stimulating nerve cells to produce repetitive discharges and eventually leading to paralysis. Commonly used to control lice. Nicotine — mimics acetylcholine Ach in the central nervous system ganglia, causing twitching, convulsions and death.

Used most to control aphids and caterpillars. Rotenone — acts as a respiratory enzyme inhibitor. Used as a piscicide that kills all fish at doses non-toxic to fish food organisms.

Limonene — affects the sensory nerves of the peripheral nervous system. Used to control fleas, lice, mites and ticks, while remaining virtually non-toxic to warm-blooded animals and only slightly toxic to fish. Commonly used against moth and butterfly larvae. Antibiotics Act by blocking the neurotransmitter GABA at the neuromuscular junction; feeding and egg laying stop shortly after exposure while death may take several days.

Most promising use of these materials is the control of spider mites, leafminers and other difficult to control greenhouse pests. Fumigants Act as narcotics that lodge in lipid-containing tissues inducing narcosis, sleep or unconsciousness; pest affected depends on particular compound.

Inorganics Mode of action is dependent upon type of inorganic: may uncouple oxidative phosphorylation arsenicals , inhibit enzymes involved in energy production, or act as desiccants. Pest group depends on compound e. Biorational Grouped as biochemicals hormones, enzymes, pheromones natural agents such as growth regulators or microbials viruses, bacteria, fungi, protozoa and nematodes.

Act as either attractants, growth regulators or endotoxins; known for very low toxicity to non-target species. Benzoylureas Act as insect growth regulators by interfering with chitin synthesis. Greatest value is in the control of caterpillars and beetle larvae but is also registered for gypsy moth and mushroom fly. Some types are known for their impacts on invertebrates reduced emergent species and early life stages of sunfish reduced weight Boyle et al.

From Radcliffe et al. Literature Reviews This section presents an annotated bibliography of references providing information on stressor-response relationships for insecticides, as well as general background on insecticide properties. Geological Survey. Circular Liess M, Shulz R Linking insecticide contamination and population response in an agricultural stream.

Environmental Toxicology and Chemistry 18 9 Relyea RA The impact of insecticides and herbicides on the biodiversity and productivity of aquatic communities.

Ecological Applications 15 2 Siegfried BD Comparative toxicity of pyrethroid insecticides to terrestrial and aquatic insects. Environmental Toxicology and Chemistry References Alkahem HF Effects of lethal and sublethal concentrations of lindane on the behavior and energy reserves of the freshwater fish, Oreochromus niloticus.

Journal of King Saud University: Science Environmental Toxicology and Chemistry 20 12 Beketov MA, Liess M Potential of eleven pesticides to initiate downstream drift of stream macroinvertebrates. Archives of Environmental Contamination and Toxicology Environmental Toxicology and Chemistry 15 10 Protectant fungicides are applied before an infection period begins to protect leaves, fruit, etc.

They will be effective only on the plant tissue present when the pesticide is applied. Protectant fungicides can stop both spore germination and host penetration but have little or no effect once the fungus has entered or colonized host plant tissue. Protectants must be applied before or during an infection period.

Persistent fungicides may protect plants for a relatively long time. Non-persistent fungicides control the pathogen on contact or for a short time so they have to be applied more frequently. The product label tells how long to wait between treatments. The interval varies with the persistence of the pesticide; environmental conditions humidity, temperature, or rainfall may make more frequent applications necessary.

Curative or eradicant fungicides have the ability to inhibit or stop the development of infections that have already started.

With some fungicides, this includes a degree of anti-sporulant activity that helps to slow disease development by limiting the reproductive potential of the fungus. This post-infection activity makes fungicide effective if the disease is established at a low level.

It is very important to remember that the curative activity may be limited. Uni-site fungicides target a specific function of fungal development so they are very prone to resistance development.

Just one mutation on the target site or any other means of avoiding or countering the effect of the fungicide, can lead to a significant loss of efficacy of the fungicide. Biosynthesis of compounds essential to the development of the fungus, respiration and cellular division are the most common targets of unisite fungicides. Multi-site fungicides act on several functions of fungal development. They are less prone to resistance development because mutations in the fungus must occur at all target sites for resistance to develop.

Narrow-spectrum - effective against only a few types of fungi. The label lists specific diseases controlled by a product. Systemics - move from the application site to plant parts where disease is occurring. Movement is usually upward toward plant tops and leaf tips. Locally systemic pesticides enter the plant where they land and move only a short distance. They may act as both a protectant and an eradicant.

Bactericides kill bacteria. These protectants cannot eradicate existing infections so they must be applied before infection occurs. Nematicides are used to control diseases caused by nematodes. They are usually toxic to warm-blooded animals and should only be used with extreme caution. Nematicides may or may not be fumigants.

Insecticides are chemicals used to kill insects and some other arthropods mites, ticks, spiders, etc. They are classified based on their structure and mode of action.

Acaricides are pesticides that are targeted to control mites; they may have little or no activity against insects. Many insecticides act at specific sites in the insect's nervous system. These usually provide very quick knockdown of insects that may ultimately die from dehydration or starvation.

The insecticides usually are sprayed on infested plants or surface on which they rest. Depending on the pest, the insecticide may kill by direct contact with the spray droplets, ingestion of treated foliage, or prolonged contact with the residue on a treated surface. Cholinesterase inhibitors interfere with nerve impulse transmission at the synapse gap. Organophosphate malathion, diazinon, acephate and carbamate carbaryl insecticides belong to this group.

They can be used as contact or residual insecticides. Once widely used for insect control, these insecticides have largely been replaced with other groups.

Bacterial toxins are produced by certain soil microorganisms. Examples include Bacillus thuringiensis Bts and spinosyns. Bt toxins disrupt the digestive tract of caterpillars so they are specific insecticides that must be eaten. Botanical insecticides are defensive chemicals extracted from plants and used for pest control. Pyrethrins are extracted from the flowers of certain Chrysanthemum species. Pyrethroid insecticides are synthetic chemicals based on the molecular structure of the natural insecticide.

Nicotine found in some solanaceous plants is the basis for neonictinoid family or insecticides. Both groups work on the nervous system. Again, insecticides can be divided into different classes based on how they affect the target insect. Some are "contact" insecticides that kill when they come into direct contact with the insect. Others are "systemic" and will be incorporated into a plant's cell structure.

Systemic insecticides kill insects when they eat the plant and ingest the insecticide chemical. Basic safety precautions should always be observed when using any pesticide. Since chemical pesticides have a negative impact on the environment and upon humans, people have found alternative ways to deal with pests in their gardens and homes. The following are a few products that do not contain any harmful chemicals and are safe to use around pets and children:. Now that you know the answer to the question: "how do pesticides kill bugs", choose your weapon against them wisely.

Chemical pesticides may be quicker, but they have an adverse effect on the environment, pets and small children. Just How do Pesticides Kill Bugs? Organophosphates Organophosphates are a class of chemicals commonly used in pesticides. The following organophosphates are commonly used in products used to kill stinging insects and beetles: Diazinon Fenthion Malathion Methyl-parathion Sulfotepp Trichlorfon Both individuals and exterminators use these pesticides.

N-Methyl Carbamate N-methyl carbamates are another class of pesticides commonly used in the home and garden. Safety Precautions Pesticides manufactured and sold within the United States include information on the proper use of pesticides and safety precautions.

Wear gloves when handling pesticides to protect your hands from absorbing the chemicals. Wear a mask when spraying any pesticide to slow down the inhalation of the particles in the air.

Leave the area promptly after spraying any pesticides, especially if they are being used in the home. Air out your home before family members resume living in areas treated by the pesticide. After applying pesticides, take off clothing used in the process and wash them before wearing them again. Wash your hands, and when possible shower, after you have completed the application of pesticides. Alternatives to Chemical Pesticides Since chemical pesticides have a negative impact on the environment and upon humans, people have found alternative ways to deal with pests in their gardens and homes.