What's in insecticide and how does it kill bugs?

Pesticides has a chapter devoted to pesticides. SLEEP COOL insect killer supplier Although I graduated in "Human Pharmacy," it's fair to say that I've read a few books on pesticides by chance.

Moreover, pesticide science and pharmacy, veterinary medicine can be said to be a brother discipline, many foreign pharmaceutical companies are also pesticide and veterinary drug companies, such as Novartis, such as Bayer, such as Takeda Pharmaceutical. Chinese EASY ON Spray starch manufacturer There are also some pesticide companies that do not have strong knowledge of pharmaceutical background, such as Mitsui Chemical in Japan and Jiangsu Suhua in my dynasty.

There are many types of insecticides, each with a different mechanism.

This is going to be a long answer. If you have chemistry, you can read all the answers. Chinese EASY ON Spray starch supplier If not, read boldface.

There are four main ways that insecticides get into insects: touch, stomach poison, fumigation and ingestion. You can tell that from the name. Touch is directly from the skin into the insect; Stomach poison is to eat it; Fumigation is when the drug enters the insect's spiracles and kills it; Endorption is the most special - when a pesticide is absorbed by a plant and then enters the insect's body and kills the insect when it eats the plant.

Different types of pesticides have different effects, and many pesticides have only one or more of the above four effects.

Four generations have passed since the invention of pesticides, and possibly a fifth.

First generation: inorganic pesticides, arsenic preparations, copper preparations (Bordeaux liquids, as in the middle school chemistry book)(Bordeaux liquids, as in the reminder, are actually fungicides), these and some native plant insecticides;

The second generation: organophosphorus, organochlorine, carbamate, pyrethrin, the pursuit of broad spectrum, acute neurotoxicity, rapid killing of pests of synthetic pesticides;

Third generation: growth regulators, juvenile hormones, which have chronic effects and interfere with normal growth and development of insects, or insecticides;

The fourth generation: pheromones, antifeedants, which are insecticides that directly regulate the behavior and activity of insects, develop more slowly, but we can significantly curb the next generation of insect populations in China;

Fifth generation: For example, the brain hormones that act on insects, the so-called insect "mind control agents," do not kill insects, but are only defensive repellents.

At present, the second, third and fourth generation pesticides are basically mixed, mainly as follows:

1) Organochlorine pesticides.

Organochlorine is divided into two categories, one is not allowed to use phenyl DDT (666), generally believed to pollute the environment, causing harm to humans and animals; The other category is newer non-phenyl pesticides, including toxaphene and endosulfan, currently the most widely used pesticide (Endosulfan is also now banned and arguably no new organochlorine pesticide varieties are available).

endosulfan

Organochlorine compounds are basically nerve agents that act on all parts of an insect's nervous system. DDT is an axon sodium channel agonist; When 666 acts on synapses, it can cause excessive release of acetylcholine from synapses, which causes insects to be in an abnormal state of excitement for a long time and eventually die.

2) Organophosphorus pesticides.

Organophosphorus is a large category of insecticides, and the well-known dichlorvos belongs to organophosphorus insecticides. Divided into the following categories:

Phosphate esters: such as domestic animals can eat gastrointestinal insect repellent naphthalene peptide phosphorus, but can not eat fast phosphorus;

thiophosphate: less toxic than phosphate, chemical stability. Now it is widely used, but also the most important, such as internal absorption of phosphorus;

systox

(It is worth noting that the endophosphorus structure is a mixture of sulfur and sulfur, while parathion seems to be more suitable for typical sulfur-phosphorus pesticides:

)

Dithiophosphate esters: the toxicity is even lower, and now the fastest growing class. For example, malathion, a low-toxicity insecticide, has no absorption effect and can only play toxicity in insects, and will be quickly hydrolyzed by phosphatase after entering the body of warm-blooded animals and lose some toxicity. At present, the ternary asymmetric organophosphate in dithiophosphate is a research focus in the field of asymmetric synthesis and pesticide science.

malathion

thiophosphate esters: In fact, dithiophosphate esters are activated by modification, not to mention;

Phosphoramidic acid derivatives: the famous methamidophos is this;

Meflon: Meflon doesn't seem to be used much now;

pyrophosphate derivatives: pepper flavor octamethylphosphorus is this;

Phosphonate (see that you are not through phosphate, is phosphonate) : trichlorfon is of this class;

trichlorphon

phosphonates: This one can only be used with clodronate.

The toxicity mechanism of organophosphorus pesticides is more complex than that of organochlorine, after all, there are many kinds.

But basically, it's all about interfering with the nervous system and inhibiting the action of cholinesterase. So once inside the insect, the nervous system will continue to be abnormally excited, overstimulated, and eventually die. Unfortunately, humans have similar neuroconduction mechanisms to insects, so many early organophosphorus chemical insecticides were also harmful to humans and animals, causing acute organophosphorus poisoning (aOPP). Therefore, at present, the main research direction of organophosphorus chemical pesticides is to study organophosphorus chemical pesticides that can be rapidly metabolized by the human body in order to reduce their toxicity to humans and livestock.

3) carbamate insecticides.

One of the earliest examples of aminogenic formates is the famous physostigmine.

Physostigmine

Physostigmine was synthesized in 1935. Over the next few decades, a large number of carbamate insecticides emerged and established their position. The most important property of carbamates is that they are particularly suitable for use as agricultural pesticides. They are highly absorbable, but have no residual toxicity. The disadvantages of some carbamate insecticides are obvious.

Carbamate is also a nervous system poison that inhibits cholinesterase (but not the same as organophosphorus pesticides). However, organophosphorus pesticides and carbamate pesticides are easy to make insects resistant, so attention should be paid to changing varieties often when using.

4) Pyrethroids.

Once upon a time, pyrethroid insecticides were considered the only choice for home insecticides. Pyrethroids are synthetic and modified compounds of pyrethroids found in natural plant pyrethroids. Pyrethrum is much more toxic than older insecticides, so only a very small amount of application can achieve the same insecticidal effect. The insecticidal spectrum is very wide, non-toxic or low toxic to mammals, does not pollute the environment, has no chronic toxicity, does not produce cumulative poisoning, is considered to be the ideal type of insecticide.

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