A group of substances isolated by extraction with organic solvents is pesticides. Pyrethrin and synthetic pyrethroids Pyrethroids decomposition time

STYLAB offers test systems for the analysis of pyrethroids in water samples and washes from food products.

Pyrethroids (sometimes mistakenly spelled "peritroids" or "perethroids") are synthetic analogs of pyrethrins, natural insecticides found in some plants of the Asteraceae family. Especially many of these substances are contained in representatives of the genera Pyrethrum (it includes various types of chamomiles), Chrisanthemum (chrysanthemums) and Tanacetum (tansy). These plants have been used by humans as insecticides, repellents, and for scenting clothing and rooms, ultimately serving the same purpose since ancient times.

Pyrethrins act very quickly: they damage the nervous system of insects when they eat or come into contact with leaves, stems or flowers. This allows plants to effectively resist pests and receive as little damage as possible. For plants, pyrethrins are not dangerous.

However, many insects have developed resistance to pyrethrins. In addition, the synthesis of these substances is expensive, and the pyrethrins themselves are rapidly degraded by sunlight. Thus, using them to protect crops is expensive and difficult. Pyrethrins are currently used in some anti-mosquito coils.

Obtaining substances comparable to pyrethrins in efficiency, speed of action and safety for plants and humans, but more persistent and cheaper, has been of interest to researchers since the beginning of the twentieth century. Pyrethroids became such compounds. Their properties are very similar to those of pyrethrins, but pyrethroids are more stable and cheaper. The first of these, allethrin, was obtained from the chlorine-containing compound of chrysanthemum acid in 1949 in the United States. Other 1st generation pyrethroids were synthesized on its basis. However, these insecticides degrade in light as quickly as pyrethrins.

In the 1960s, second generation pyrethroids, which are more stable to light, were developed. The potency of these substances is hundreds of times greater than that of pitrethrins. The effectiveness of 3rd generation pyrethroids is even higher, and these substances allow you to fight a wide range of insects.

Pyrethroids are divided into two types, depending on whether their molecule contains a cyano group (the same as in hydrocyanic acid). Cyanopyrethroids, or type II pyrethroids, are more toxic than type I pyrethroids precisely due to this group. These include, for example, cyfluthrin, cyhalothrin and its isomers, cypermethrin and its isomers, deltamethrin and others.

All pyrethroids are fat-soluble and persist for a long time in the cuticle of the leaves, which provides effective plant protection. The same property allows them to be retained in the skin and adipose tissues of mammals, including humans, and excreted in milk. Pyrethroids can cross the blood-brain barrier into the brain and cross the placental barrier. The latter means that they can harm the embryos.

Pyrethroids are toxic to mammals. However, the minimum toxic doses of these substances for insects are much lower than for mammals, which allows the widespread use of these insecticides. In addition, pyrethroids are excreted from the mammalian organism rather quickly.

The mechanism of action of pyrethroids is based on overexcitation of the nervous system. This results in muscle spasms, seizures, and subsequent paralysis and death. Cyanopyrethroids, in addition, prevent its inhibition (i.e., the restoration of the normal state of the nervous system), which enhances the effect. Insects quickly die from this effect. In mammals, including cats especially sensitive to pyrethroids, fatal poisoning occur much less frequently, but such cases are known.

Acute pyrethroid poisoning is characterized by an increase in temperature, which can last for several days, headache and dizziness, weakness, itching, impaired coordination of movements. Tremors, hyperactivity, agitation, and involuntary muscle contractions may occur. Poisoning with type II pyrethroids, such as cypermethrin, is more severe, with convulsions and seizures, and increased salivation.

Chronic exposure to pyrethroids, such as permethrin, causes impaired motor coordination in rats or skin irritation (when applied to it) in rabbits. Some studies talk about the connection of chronic exposure to pyrethroids with serious pathologies of the nervous system, a decrease in immunity and the occurrence of allergies. However, such conclusions are questionable due to the methods of sampling (in particular, in some cases a vacuum cleaner was used for this) or the statistical unreliability of the results.

Some pyrethroids, for example, are recognized as possible carcinogens. Permethrin at high promotes the formation of non-cancerous tumors, in particular liver tumors, in mice. But in general, the effect of chronic exposure to pyrethroids on humans has not been studied. However, these substances are unstable and are rapidly eliminated from the body, which reduces the likelihood of chronic effects.

Pyrethroids are rapidly destroyed by sunlight and air. They are unstable in the soil and practically do not penetrate into groundwater... These substances are poorly soluble in water. Therefore, pyrethroids are among the most environmentally friendly pesticides. However, these substances should not be allowed to enter waterways, as they are very dangerous for fish and aquatic invertebrates. For birds, these substances are of low toxicity.

Pyrethroids are dangerous not only for harmful, but also for beneficial insects, including bees. Therefore, these drugs, like other pesticides, should be used with caution. Agricultural pests are capable of developing resistance (resistance) and cross-resistance (resistance to several similar drugs at once) to these insecticides. Therefore in agriculture insecticides containing several active ingredients, including pyrethroids, are often used. Preparations based on cypermethrin, alpha-cypermethrin (cis-isomers of cypermethrin), permethrin, bifenthrin, beta-cyfluthrin, lambda-cyhalothrin (cyhalothrin, cichalothrin), tefluthrin, prometrin, gamma-cyhalothrin (cyhalothrin), deltamethrin, deltamethrin , esfenvalerate are approved for use in the Russian Federation.

The content of pyrethroids in water, soil, air and food products regulated by the "Unified Sanitary and Epidemiological and Hygienic Requirements for Goods Subject to Sanitary and Epidemiological Supervision (Control)", as well as TR CU 015/2011 "On grain safety"... The current legal regulations can be found on the website compact24.com.

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Natural pyrethroids (pyrethrins) are found in the flowers of pyrethrum (Dalmatian chamomile), their analogs are artificially created synthetic pyrethroids.

The benefits of pyrethroids are the following:

In addition, synthetic pyrethroids are lipophilic substances that are well retained by the cuticle of the leaves and, penetrating into them limitedly, provide a deep insecticidal effect.

One of the most common pyrethroids at the moment is his.

History

The dried flowers of some types of chamomile were used as more by the soldiers of Alexander the Great, then in ancient China and in the Middle Ages in Persia. The beginning of scientific research of these substances can be considered 1694, when the plants of the Dalmatian, or ash-leaved, chamomile were first described, which grew wild in the Caucasus and Dalmatia (region of Yugoslavia).

Later it was found that flowers of several species of chamomile (genus Chrysanthemium of the family Asteraceae - Asteraceae) have insecticidal properties, but Dalmatian chamomile (Chrysanthemium cinerafolis or Pyrethrum cinerariifolium), whose inflorescences contain up to 1.5% pyrethrin, is most widespread.

Precursor to pyrethroids

Precursor to pyrethroids

Insecticide "Killer of flying" against household flying insects, produced in the 30-40s of the last century. Contains an extract of Pyrethrin 1 and Pyrethrin 2, as evidenced by the inscription on the package.

In Europe, dried and crushed inflorescences (pyrethrum), which have a remarkable property of killing cockroaches, bedbugs, flies and mosquitoes, became known more than 200 years ago thanks to traders from Armenia who sold them as Persian dust (insect powder) ... Dalmatian chamomile has been introduced and grown successfully in Japan, Brazil and the United States. Since 1890, the production of mosquito sticks began in Japan, and later spirals, which burned for a long time and scared away midges. By 1938, the world produced about 18 thousand tons of dried flowers per year, of which about 70% in Japan.

The chemical study of the factors of insecticidal activity of pyrethrum began in 1908. In the 1920s, the presence of a cyclopropane ring in pyrethrum molecules was proved and the structure of pyrethrin I and pyrethrin II was established. It was found that the insecticidal components of pyrethrum flowers contain six ketoesters of chrysanthemum and pyrethrinic acids, which are very similar structurally and determine the insecticidal activity of pyrethrum.

In the 30s of the XX century, based on the extraction of pyrethrins with organic solvents from chamomile flowers, the production of pyrethrum preparations - viscous, heavy, white oils almost odorless, insoluble in water and containing from 2-10 to 90% of a mixture of pyrethrins - was started. Pyrethrins are used primarily for control and storage. The drugs were harmless to humans and animals, but they were expensive to manufacture, unstable and quickly lost their insecticidal activity.

The study of the mechanism of their insecticidal action has played a decisive role in the further direction of the synthesis of new pyrethroids. As a result of further research on the synthesis of pyrethroids carried out at the Rotterdam Experiment Station (England), a highly active and stable external environment preparation NRDC-143 () obtained by including dicacid in the pyrethrin I molecule.

In the USSR, the study of pyrethroid compounds was first begun at VIZR in 1977.

Effects on harmful organisms

High lipophilicity provides instant penetration of pyrethroids through insect integuments, ensuring rapid defeat. Further, pyrethroids act on, causing paralysis and death.

Unlike many other compounds, pyrethroids act at low positive temperatures, which makes it possible to use them in the early spring. According to other sources, best results when using pyrethroids, they are possible at moderate positive temperatures.

The protective effect lasts 15 - 20 days, - 20-30 days.

Pyrethroids are especially effective against Lepidoptera, Hemiptera, Diptera, Homoptera and Coleoptera.

A number of pyrethroids also have acaricidal action. For example, pronounced insectoacaricides are (talstar) and (maurik).

Enzyme attack on pyrethroids

Enzyme attack on pyrethroids

Directions of attack of enzymes, leading to the deactivation of pyrethroids in a living organism. The arrows show the sites of hydrolysis under the action of esterases and hydroxylation (insertion of an oxygen atom along communication C-H) or epoxidation with subsequent oxidation and cleavage. The thickness of the arrows reflects the relative importance of a particular direction of attack:

Also, cross-resistance is often manifested, in which the use of drugs based on one active substance leads to the emergence of insect races resistant not only to this, but also to other active substances. Overcoming is a major challenge.

The emergence of resistant races is also associated with an increase in the activity of certain enzymes: in resistant insects, enzymes are more effective in deactivating toxic substances entering the body. If an insect is simultaneously acted upon with a pyrethroid by another compound that suppresses the activity of these enzymes, then the functional effect of the pyrethroid will increase when the deactivation process is slowed down. Knowing the mechanism of occurrence, this is what they do in practice, using a pyrethroid in combination with a substance () that does not have insecticidal activity, but by inhibiting certain enzymes that enhance the effect of pyrethroid.

Application

In agriculture

In private households

Toxicological characteristics

Pyrethroids are relatively stable in sunlight; on inanimate surfaces they can persist for up to one year (). They poorly migrate in the soil, under the influence of microflora they are destroyed within 2 - 4 weeks, almost do not penetrate into plants. Their half-life (DT 50) on the surface of plants is 7 - 9 days, the remains are found within 20 - 25 days.

Due to their lipophilicity, the substances are well retained by the cuticle of the leaves and are not washed off by rain, and the low vapor pressure provides a long residual effect and prevents the spread of pyrethroids in the environment by air currents. The same physical properties limit the mobility of pyrethroids in the soil: due to good adsorption, the spread of pyrethroids is possible only with soil erosion.

In water

When introduced to animal organism pyrethroids enter fat deposits and, moreover, they are excreted from adipose tissues within 3-4 weeks, and from the brain - much faster. Pyrethroids are eliminated from the body the faster, the more toxic the drug.

For warm-blooded

Cumulative properties are poorly expressed, with the exception of deltamethrin.

Into the human body

Symptoms

As a result of many years of research on pyrethrins, chemists have succeeded in obtaining photostable pyrethroids suitable for use in agriculture.
The first synthetic pyrethroids based on permethrin, cy-permethrin, deltamethrin and fenvalerate entered the market in 1976 ... 1977.
High insecticidal activity, long-term protective effect at low consumption rates, which are not kilograms, as in COS, not hundreds of grams, as in FOS, but only tens of grams, were highly appreciated by plant protection specialists.
The range of pyrethroids has been expanding every year, and now they dominate the world among plant protection products from pests.
Modern pyrethroids are esters of 3-substituted 2,2-di-methylcyclopropanecarboxylic (chrysanthemic) acid (I) or isosteric acid that has lost the propane ring (II) and the corresponding alcohol containing one or two saturated bonds. A feature of these substances is the presence of 4 ... 8 optical or geometric isomers, which differ in biological activity. For example, drugs that differ in the content of isomers based on cypermethrin, alpha-, beta-, zeta-cypermethrin are on sale.
Chrysanthemum acid is based on molecules of permethrin, cypermethrin, deltamethrin, isosteric acid - fenvalerate.
Synthetic pyrethroids - lipophilic substances, are well retained by the cuticle of the leaves and, penetrating into them limitedly, provide a deep insecticidal effect. They are not volatile, photostable, and can persist on an inanimate surface for up to 12 months (permethrin).
Synthetic pyrethroids are not toxic to plants, their half-life is different plants 2 ... 20 days, residual amounts of drugs retain their biological activity on herbs for a longer time.
Pyrethroids poorly move in the soil and decompose in it with the participation of microorganisms. Their half-life in soil is 1 ... 10 weeks. The metabolites are non-toxic and further decompose to carbon dioxide.
Synthetic pyrethroids are preparations of contact-intestinal action, they have high insecticidal activity, are effective against lepidoptera, beetles, flies. Pyrethroids, which have entered the market in recent years, also have acaricidal action.
By the mechanism of action, pyrethroids are similar to COS. They disrupt the function of the nervous system, acting on sodium-potassium channels and calcium exchange in synapses, which leads to the release of an excessive amount of acetylcholine (ACh) during the passage of a nerve impulse. Poisoning is manifested in strong agitation, damage to the motor centers.
With prolonged use of synthetic pyrethroids, insects develop acquired resistance (group and cross).
When injected into the stomach, pyrethroids can be highly, medium and low toxic for warm-blooded animals, cause severe skin irritation, some of them have a weak carcinogenic and embryotoxic effect. However, they are not considered particularly dangerous for humans, since they are used at very low consumption rates.
Decis. The active ingredient is Deltamethrin - (1R) -cis-3- (2,2-dibromovinyl) -2,2-dimethyl-cyclopropanecarboxylic acid (S) -3-phenoxy-a-cyanobenzyl ether.
Deltamethrin is effective against sucking insects at a consumption rate of 5 ... 12 g. per 1 ha, gnawing - 12 ... 17, coleoptera - 25 ... 50 g. per 1 hectare.
The efficiency of potato treatment with Decis, EC (25 g / l) against the Colorado potato beetle at a consumption rate of 0.15 l / ha on the 3rd day was 95 ... 99%. The duration of the protective action is 15 days.
Deltamethrin-based preparations are approved for use in wheat, barley, corn, sunflower, potatoes, beets, peas, cabbage, tomato, carrots, alfalfa (consumption rate 0.1 ... 0.6 l / ha, waiting period 15. .30 days), as well as for the processing of many medicinal, woody plants, grasslands inhabited by locusts, unloaded storage facilities (0.2 ... 0.4 ml / m2) and grain (20 ml / t).
For use in personal subsidiary plots, deltamethrin is produced in the form of a pencil (K) (1 pencil weighing 30 g per 10 liters of water is used to spray an area of \u200b\u200b100 m2) and briquettes (B) (5 g are used per 10 liters of water).
Deltamethrin is highly toxic for warm-blooded animals and humans (SD50 for rats 128 ... 138 mg / kg). Cumulative properties are not expressed, weak allergen, embryotoxic effect is noted. It irritates the skin, mucous membranes, and non-healing ulcers form upon repeated application.
This pyrethroid is not persistent in the environment. The results of tens of thousands of experiments indicate that when used correctly, residual amounts of deltamethrin do not accumulate in the soil and are not found in plants.
MPC in soil - 0.01 mg / kg (tr.), In water - 0.01 mg / l, in air - 0.1 mg / m3. The ML in most types of agricultural products is 0.01 mg / kg, residual quantities are not allowed in carrots.
Rovikurt. The active ingredient is 3-phenoxybenzyl- (1 / R, 1S, cis, trans) -2,2-dimethyl-3- (2,2-dichlorovinyl) cyclopropylcarboxylate. The pure substance is a light oily liquid with a slight odor, readily soluble in organic solvents. There are four known isomers of permethrin. The technical product contains a mixture of cis and trans isomers (2: 3).
Permethrin is an intestinal contact insecticide with a protective effect for about 15 days. It is highly effective against gnawing and sucking insects, dangerous for bees.
Low toxicity for humans and warm-blooded animals (SD50 for rats 4000 mg / kg), has a weakly expressed property to accumulate in the body.
Recommended on apple trees against apple moth, golden moth, aphids, moths, on cherries against cherry flies, on cabbage against scoops, whites and moths, on sugar beets against weevils, aphids and fleas, on gooseberries against sawflies and on currants against leaf rollers, aphids, moth.

13. Synthetic pyrethroids

The use of pyrethroids in the form of powdered flowers of the Persian, Dalmatian and Caucasian chamomile of the genus Pyrethrum is known even before our era, but the chemical structure was established only in the 50s of the last century. The active insecticidal substances in the powder are cyclopropanecarboxylic acid derivatives - cinerin 1 and 2, pyrethrin 1 and 2, and in small amounts dehydro-derivatives - jasmoline 1 and 2. These substances are liquids with a faint odor and are quickly inactivated due to oxidation and hydrolysis. Due to the fact that the synthesis of cinerins and pyrethrins is difficult, their analogs - synthetic pyrethroids - are obtained for practical use.

The synthesized and studied pyrethroids are derivatives of cyclopropanecarboxylic acids, in particular, chrysanthemum and monocarboxylic acids. Most of the drugs used in practice are based on permethrin, cypermethrin, deltamethrin, fenvalerate and other synthetic pyrethroids.

Almost a quarter of all insecticides and acaricides (40 out of 185) included in the list of pesticides approved for use in 2000 are synthetic pyrethroids. The main advantage of substances in this group is their high insecticidal and acaricidal activity with a pronounced selectivity of action, which is many times higher than the selectivity of FOS. Therefore, pyrethroids are used in very small quantities - hundreds of grams per hectare. These compounds are unstable, however, when used in agriculture and veterinary medicine, they can get into the environment and cause poisoning of people and animals.

The toxicity of pyrethroids to warm-blooded animals varies. Among them there are high-, medium- and low-toxic drugs. For warm-blooded animals, pesticides containing a cyanogen group (decis, sumicidin, etc.) are more toxic.

The cumulative properties of most pyrethroids are not clearly expressed, so the likelihood of chronic intoxication is low.

Rovikurt. Light oily liquid with a weak odor, slightly soluble in water (10 mg / l), well - in most organic solvents. Contains the active ingredient permethrin. Used in agriculture. In veterinary medicine, permethrin is used (ambush, corsair). Produced in the form of an emulsion concentrate containing up to 25% of the active substance. Preparative forms - Stomazan (Hungarian drug), Creopyr, Anometrine and Pirvol.

Plants are protected from insects and mites with 0.01-0.02% water emulsions at the rate of 0.1-0.2 kg / ha (based on the active ingredient). It is used for spraying industrial, grain, vegetable crops during the growing season, as well as for the treatment of fruit shrubs, grapes, medicinal plants, deciduous and coniferous trees. The animals are treated by spraying or bathing in floating baths with 0.05-0.1% aqueous emulsion of the drug. It is not allowed to handle lactating animals.

Permethrin toxicity data is inconsistent. LD50 for white mice and rats varies from 455 to 4000 mg / kg, which, apparently, is associated with different content of isomers in the technical product.

The pesticide is very toxic to bees and fish.

In sheep treated by bathing in a 0.05% water emulsion of pirvola, after 3 days, 0.051 mg / kg is found in muscle tissue, 0.045 mg / kg in the liver, and 0.043 mg / kg permethrin in the kidneys. Through Shsut, pesticide residues are found only in muscle tissue in trace amounts (EK Rakhmatullin, 1997).

Arrivo, inta-vir, cymbush, cyperkil, cyrax, scherpa, cytkor, cy-pershans. Contains the active ingredient cypermethrin. Most drugs are colorless liquids with a weak odor, slightly soluble in water (Yumg / l), well in most organic solvents.

Produced in the form of ke and tablets. They are used for spraying during the growing season of grain, industrial, vegetable and melon crops, grapes, deciduous and coniferous trees, urban green spaces, grain storage areas and in other cases to combat insects and ticks.

To protect animals from insects and ticks, water emulsions of Creoquine and Zipek are used in 0.005-0.01% concentration. Preparations containing cypermethrin are moderately hazardous pesticides with LD50 for white rats of 250-300 mg / kg. Highly toxic for bees, CK5o for fish 0.0012 mg / l.

When processing sheep by bathing in aqueous emulsions containing cypermethrin at 0.005% concentration, the residues in fat, liver, kidneys and heart after 5 days are 100, 89, 72 and 62 μg / kg, respectively. After 10 days, traces of the drug are found only in fat. The release of the pesticide in sheep milk has not been established.

After the treatment of calves with an aqueous emulsion of the Inta-vir preparation containing cypermethrin at 0.05% concentration (based on the active ingredient), the greatest amounts of pesticide residues are found in fat: after 5 days - 0.033 mg / kg, after 10 - only traces. After 15 days, there are no pesticide residues in organs and tissues (AN Mitasov, 1994). ",

Decis, biorin, deltacid, K-edema, K-obiol, Fas. Contains ^ the active substance deltamethrin. Combined npena ^ S rats bifetrin (deltamethrin + fenthion) and decis-quick (delta * [metrin + heptenophos), like the above pesticides ^, are used mainly for spraying plants during the growing season, sometimes in the beginning of flowering on the same crops as c\u003e other peritroids, as well as for the processing of pastures (for the destruction of locust larvae), forage and medicinal plants, fruit, many deciduous and coniferous trees.

In preparative form, these can be emulsion concentrates, briquettes and wettable powders. These drugs are effective in cases where the pests are resistant to FOS, COS and carbamates. Practically insoluble in water, readily soluble in organic solvents. For plant protection they are used in the form of water emulsions at a rate of 0.01-0.05 kg / ha.

Animals are treated by spraying or bathing in baths containing an aqueous emulsion of preparations in 0.005% concentration. LD50 for rats when taken orally is 128-139 mg / kg, with cutaneous application of aqueous emulsions LD50 2500 mg / kg. Highly toxic to bees, beneficial insects and fish; CK5o for fish 0.1 mg / l. Unstable in the environment. Residual amounts are not found in the soil, nor are they detected in plant foods. According to EK Rakhmatullin (1997), they are retained in animal tissues for a longer time compared to permethrin and cypermethrin.

In samples of muscle tissue, liver and kidneys of sheep treated by bathing in an aqueous emulsion of butox containing 0.005% decamethrin (based on the active ingredient), the amount of residues 7 days after treatment was 0.3, 0.044 and 0.042 mg / kg, and after 10 days -0.014, 0.019 and 0.02 mg / kg, respectively. No pesticide residues were found 35 days after treatment.

Other synthetic pyrethroids - danitol (fenpropatrin), zeta and fury (zeta-cypermethrin), karate (lambda-cyhalothrin), kinmix (beta-cypermethrin), mavrik (tau-fluvalinate), sumi-al-fa (esfenvalerate), sumicidin phenaxine and phoenix (fenvalerate), talstar (bifenthrin), fastak (alpha-cypermethrin) and others are used in field cultivation, horticulture and forestry.

The disadvantage of pyrethroids is that insects and ticks get used to them. A multiple increase in the concentration of solutions and the frequency of treatments is ineffective. In such cases, it is required to change the drug or replace it with pesticides from other chemical groups. All drugs in this group have high selective toxicity towards insects and ticks.

Toxicodynamics. E.K. Rakhmatullin (1997) in experiments with puron containing cypermethrin, proposed for application to the skin of the back of animals, found that the insecticide in therapeutic doses and 10 times higher doses did not cause clinical symptoms of intoxication in animals, but significantly increased in the first 5 days after application to the skin, blood cholinesterase activity, especially when using large doses.

In the following days, cholinesterase activity decreased by 30-40% compared to the control.

S. Cosida (1973) observed inhibition of the activity of microsomal oxidases under the action of natural pyrethroids.

In laboratory animals (white rats), pyrethroids (decis, sumicidin, cymbush) act on the central nervous system in toxic doses. In animals, depression is observed, followed by excitement, tremor, convulsions, cholinesterase activity decreases in all studied substrates, including in the brain. This leads to the accumulation of the mediator of cholinergic synapses - acetylcholine, therefore, its cholinomimetic effect is manifested. Pyrethroids in rats act hepatotoxic, which leads to a decrease in transamination enzymes, alkaline phosphagase, liver and serum cholinesterase, total protein and urea.

In the body of warm-blooded animals, pyrethroids are rapidly metabolized and excreted in the urine, part of the drugs are excreted in the feces. The metabolic rate of pesticides depends on their chemical structure.

Long-term effects have not been identified in pyrethroids.

Clinic. There were no cases of poisoning of cattle, sheep, deer, pigs and other animals when they were treated with preparations containing permethrin, cypermethrin, deltamethrin and fenvalerate.

Pyrethroids have a therapeutic index of more than 10, therefore, animal poisoning is unlikely even with a 5-fold increase in doses.

An increase in the recommended concentration (0.005%) by 10 times (0.05%) when using drugs based on cypermethrin and deltamethrin for treating sheep, cattle, pigs against psoroptosis, sarcoptic mange and other diseases caused by ticks and insects is not accompanied by the appearance of clinical symptoms of intoxication.

When laboratory animals are poisoned with deltamethrins, salivation, chewing movements, tremor, hyperactivity, muscle contraction, and convulsions are noted. Skin sensitivity and neuro-reflex excitability are reduced.

In farm animals, symptoms are nonspecific.

When drugs are taken inside, excitement is first noted, and then depression, appetite is reduced, skin sensitivity and neuro-reflex excitability are reduced.

Treatment. No antidote therapy is available. When pyrethroids are ingested in large quantities with treated plants, activated charcoal with water should be administered.1 Vomiting can be induced in pigs. Subsequently, the animals are prescribed saline laxatives, oil laxatives should not be given. Symptomatic treatment is carried out depending on the indicator; knowledge.

Pathological changes. They were established in laboratory animals, which were injected with synthetic pyrethroids in the most toxic and lethal doses. Characterized by hemodynamic disorders in internal organs and the brain, punctate hemorrhages under the epicardium and endocardium, degenerative changes under the epicardium !, and the endocardium, degenerative changes in the liver, catalysm inflammation of the mucous membranes of the gastrointestinal tract (E. K. Rakhmatullin, 1997).),

Vetsanexpertiza... The remains of pyrethroids are determined by the method | GLC. Establishing the presence of synthetic pyrethroids in tissues ”! bees and fish provides a basis for the diagnosis of poisoning.

When processing the skin by spraying or bathing, synthetic pyrethroids remain in the body for an average of 10-14 days. According to EK Rakhmatullin (1997), the remains of pyrethroids containing deltamethrin, in case of poisoning, linger for up to 30 days. Therefore, depending on the type of insecticide-acaricide, the treated animals should be killed after 20-35 days. MRLs for residues in animal tissues have not been established in our country. In fish, the MRL for pyrethroids is 0.0015 mg / kg. In case of forced slaughter, products are examined for the presence of drug residues, and if they are available, meat and by-products should not be allowed in food. MLs for vegetables, fruits and grains are listed in the annexes.

Prevention. Preparations of synthetic pyrethroids are used only in accordance with the instructions. It is prohibited to graze animals near treated plantations before the end of the waiting period.

POISONING WITH CHEMERITSIA

Poisoning of animals with hellebore (Veratrum L. continues to be a significant problem. In Bulgaria, hellebore is a widespread meadow plant in the foothill and mountain regions. The country is especially represented by white hellebore (Veratrum var. Lobeliana) and black, which in some areas account for 15 20% of the total herbage.It is known that hellebore contains several alkaloids, of which the toxic effect is exerted by protoveratrin, protoverathridine, zhervin, etc. Their content in individual parts of the plant is not the same. In the rhizome, the level of alkaloids reaches 1%, in the aerial part - up to 0, 5% When drying and ensiling, the alkaloids content does not decrease.Due to the solubility of protoveratrin in water, it turns into a liquid mass in the lower layers of the silage.

Cattle, pigs, sheep, goats, poultry are sensitive to hellebore. Young animals are more sensitive than adult animals. There is also a breed predisposition. Animals of improved breeds are more easily poisoned. The toxic dose of the aboveground part of hellebore for cattle is 400-800 g, for pigs -50-100 g, lambs - 20-50 g, adult sheep and goats - 50-80 g. Toxic dose of seeds and rhizomes for poultry - 2-5 g.

Toxic effect. The hellebore, which entered the digestive apparatus, is digested under the influence of various enzymes and secretes the alkaloids contained in it, which have a local irritating effect on the mucous membrane and motor endings. After resorption, alkaloids exhibit a strong toxic effect on the central nervous system. In the digestive tract, inflammation develops, and in ruminants, the contraction of the proventriculus increases and their motility slows down, and then atony sets in. In the central nervous system, some motor centers of the subcortical layer are excited, which may result in the manifestation of spasm. After the resorption of protoverin, dysfunctions of the central nervous system occur, as a result of which the eyelids of the eyes in animals close. In the medulla oblongata, the nuclei of N. vagus, the respiratory center and vasomotor nerves are excited, which, respectively, causes disturbances in breathing, blood circulation and cardiac activity.

Clinical signs... In cattle, intoxication is manifested by increased salivation, attempts to rotate in place, spasms of the esophagus, strengthening and then slowing down.

scar motility until it stops completely, increased sweating, spasms of the striated muscles and muscle tremors. The animals are disheveled, restless and frightened. The general condition is also disturbed. Cardiac activity is at first slowed down, and later accelerated. Blood pressure is high, blood vessels pulsate distinctly, breathing is difficult due to spasm of the respiratory intercostal muscles and diaphragm. The death of animals occurs due to respiratory paralysis and vasomotor collapse.

In pigs, the first typical sign of poisoning is trying to rotate in place. In addition, they constantly move and rummage in the litter, often lie down and get up. They have muscle tremors all over their bodies. Cardiac activity and breathing are at the same time speeded up. Death occurs due to respiratory paralysis.

For a bird, a characteristic sign of poisoning is the inability to stand on its feet due to muscle weakness. Rotational head movements and progressively worsening diarrhea are also noted. Cardiac activity and breathing are quickened. Birds die due to respiratory paralysis a few hours after poisoning.

Pathological changes. Autopsy reveals a pronounced hemorrhagic inflammation of the stomach and intestines. Sometimes ulcers can be seen on the mucous membrane of the abomasum and scar. The liver is filled with blood, enlarged and has rounded edges; the gallbladder is also enlarged and filled with bile. In the kidneys, subcapsularly and in the cortical part, a pronounced hyperemia and punctate hemorrhages are observed.

The prognosis for animal poisoning with hellebore is negative.

The diagnosis is made on the basis of the determination of an excessive amount of leaves and stems of hellebore in the feed and their remains in the contents of the stomach. A laboratory chemical study of feed and stomach contents, in which a positive reaction to alkaloids (protoverathrin) is determined, is of decisive importance for the diagnosis.

Treatment. Muscle relaxants or antipsychotics are used. The results of the studies of the authors of the book indicate that a good effect can be achieved from the use of chlorazine (ampoules of 25 ml), as well as glucose (3 ampoules of 250 ml of 20% glucose solution for large animals and one ampoule of 50 ml of 20% glucose for small ruminants). Chlorazine is administered intravenously (1-2 times a day). An even better effect can be achieved by the combined use of magnesium sulfate with chlorazine or the use of magnesium sulfate alone.

For gastroenteritis, enveloping agents are used - a decoction of flaxseed or a 1.5% solution of pectin in water at a dose of 250 ml for large and 20-30 ml for small species of animals alone or in combination with magnesium sulfate - a saline laxative.

To maintain cardiac and pulmonary activity, therapy with cardiotonin and ephedrine is prescribed. For liver damage, methionine is used (intravenously).

Prevention. It is necessary to control the botanical composition of feed mixtures. Hay should not contain more than 2% hellebore leaves.

The history of pyrethroid insecticides may well be called floral, since natural pyrethroids are found in Dalmatian chamomile flowers. But progress, in the form of chemical synthesis, has made pyrethroid-based insecticides an affordable means of controlling harmful insects in agricultural crops. different types... At one time, more than 70 years ago, it was an incredible breakthrough in the segment of insecticides, the prevailing number of which were organophosphorus compounds, which have a number of disadvantages and limitations. usually act on the central nervous system of insects. At the same time, a distinction is made between contact preparations and systemic insecticides. The mechanism of attack of synthetic pyrethroids is also associated with an effect on the nervous system, it is implemented systemically, causing paralysis a few hours after the application, and then the death of the insect. These contact-intestinal preparations have selective toxicity, high insecticidal activity and minimal ecotoxicity. It was the last property of pyrethroids that made it possible to switch to the creation of soil insecticides and effective fumigants. Of the technological advantages in the context of "insecticide characteristics", it is important that synthetic pyrethroids act at low positive temperatures from + 5-8 C, which implies their use in the early spring period.
Synthetic pyrethroids are effective against gnawing and sucking pests, especially against Lepidoptera, Hemiptera, Diptera, Homoptera, and Coleoptera. Most often they are used against leaf-eating insects.
However, as with any group chemicals plant protection for pyrethroids have properties that must be treated with understanding (namely, first to understand and then to apply). 1) Unlike organophosphate insecticides (FOS) and carbamates, pyrethroids do not kill hidden pests. But this is solved by using their tank mixtures with FOS, neonicotinoids. For example, against sucking pests (cereal aphids, bugs, and thrips), mixtures of synthetic pyrethroids with FOS are most effective, since they provide high initial toxicity and duration of protective action. 2) The limiting factor for pyrethroids is the air temperature during processing - up to 25 C. What if the temperature is higher? It is not difficult to assess the risks (for an experienced agronomist) and predict the loss of biological effectiveness, which are at the level of 15% (in the heat, the evaporation of the drug is higher and insects hide deeper), comparing them with the probable loss of yield (of course, in product prices). Insecticides of the new generation easily overcome the temperature barrier up to 28 C and ensure the reliability of the effect.
The classic representative of synthetic pyrethroids is the insecticide Zepellin, which contains alpha-cypermethrin. It is effective in the fight against the main types of harmful insects on cereals, sugar beets, sunflowers and other crops (harmful bug, flea beetles, aphids, thrips, leafhoppers, piavitsa, flies, etc.), is characterized by the rapid development of the effect, the so-called "knockdown - Effect", high efficiency at the larval stage of insect development, a strong deterrent (repellent) effect, which together prolongs the protective effect of the drug. Zeppelin is used at low consumption rates, the drug is compatible with many pesticides and agrochemicals, which makes the choice of this insecticide more attractive for many business executives.
Combined insecticide Dexter contains a synthetic pyrethroid lambda-cyhalothrin and acetamiprid, which belongs to the neonicotinoid class, thanks to which the effect is prolonged up to three weeks. Dexter infects pests (including hidden ones) directly when spraying, as well as when feeding on the treated plant and inside it: the contact-systemic properties of the drug provide exceptional activity against a wide range of pests at all stages of their development.
Synthetic pyrethroids or preparations containing substances of this chemical class provide effective protection of plants both during routine treatments of crops with a wide range of insect pests and in case of force majeure (in case of danger of epizootics, edge and local treatments ). In a word, pyrethroids are always an instant "blow" to the pest and a guarantee of the success of insecticidal treatments in difficult weather conditions.