Hormonal insecticides

Hormonal insecticides are a class of chemicals that mimic or disrupt hormonal processes in insects. They affect the endocrine system of pests, disrupting their development, metamorphosis, and reproductive functions. Hormonal insecticides are widely used in agriculture and horticulture for effective control of insect pest populations, reducing their numbers and preventing damage to crops.

Objectives and importance in agriculture and horticulture

The main goal of using hormonal insecticides is to manage pest insect populations by disrupting their life cycles. This helps reduce pest numbers, increase crop yields, and improve product quality. In horticulture, hormonal insecticides are used to protect ornamental plants, fruit trees, and shrubs from various insects, preserving their health and aesthetic appeal. Due to their specificity, hormonal insecticides are an important component of integrated pest management (ipm), ensuring sustainable and efficient agriculture.

Relevance of the topic

Given the growing global population and increasing food demand, effective management of insect pests has become critically important. Hormonal insecticides offer more environmentally safe and targeted control methods compared to traditional chemical insecticides. However, improper use of hormonal insecticides can lead to the development of resistance in pests and negative environmental consequences, such as reducing populations of beneficial insects and polluting the environment. Therefore, studying the mechanisms of action of hormonal insecticides, their impact on ecosystems, and developing sustainable application methods are key aspects of modern agrochemistry.

History

Hormonal insecticides are a group of chemicals that affect the hormonal system of insects, disrupting their normal development, which can lead to death or cessation of reproduction. They do not kill insects directly but instead block their natural physiological processes, such as molting or metamorphosis, disrupting their life cycle. The development of these insecticides began in the mid-20th century, and during this period, they evolved from experimental chemicals to widely used crop protection agents.

• Early research and discoveries

Research into hormonal insecticides began with the study of insect metamorphosis biology. In the 1920s and 1930s, scientists began to recognize the importance of hormones in the molting and metamorphosis processes, particularly those that regulate the transformation of larvae into pupae and pupae into adults. During this time, it was established that insect hormones control their growth, development, and behavior.

In the 1930s, a group of scientists began searching for substances that could affect the hormonal system of insects and use them as pest control agents. One of the first steps in this direction was the discovery that exogenous hormones introduced into an insect’s body could disrupt the molting process. Soon after, chemists began developing synthetic chemicals that could mimic these hormones' effects and be used in agriculture.

• Development of the first products

The first wave of research on hormonal insecticides took place in the 1950s. One of the first products to use the hormonal action principle was ethiproximide, which disrupted molting in insects. However, it was not as effective as expected and did not gain widespread use. In the 1960s, chemists began working to improve these products, and propoxur was synthesized, which turned out to be more effective and environmentally safe.

A significant achievement was the creation of insecticides that act on the metamorphosis process. These products began to be used to control pests like aphids, flies, weevils, and many other agricultural pests. Their advantage was that they affected insects at different stages of their life cycle, especially during the larval and pupal stages.

• Rapid development and use of hormonal insecticides

The 1960s and 1970s saw the widespread use of hormonal insecticides in agriculture. Products based on chlorfenapyr, diflubenzuron, and other chemical compounds became the primary means of protecting various crops from pests. They were especially effective in combating insect pests on crops like cotton, tobacco, vegetables, and fruits. These products acted on the exogenous hormones of insects, blocking their ability to molt, which eventually led to their death or developmental halt.

This period also saw the active use of hormonal insecticides for protecting plants from insect-borne diseases. The products were used not only in agriculture but also in forestry and in the fight against parasites in public health.

Safety and environmental issues

Despite their high effectiveness, hormonal insecticides were not without problems. They proved to be highly toxic not only to insects but also to other organisms, including beneficial insects such as bees and ladybugs, as well as animals. Their high volatility and accumulation in ecosystems became a serious issue. Hormonal insecticides polluted the soil, water bodies, and plants, leading to long-term environmental consequences.

Additionally, many of these products caused resistance problems in insects, which reduced their effectiveness over time. As a result, in the late 1970s and 1980s, restrictions were introduced on the use of some hormonal insecticides, especially in countries with advanced environmental standards.

Modern approaches and issues

Today, hormonal insecticides are still in use, but their application has become more limited. Due to safety concerns, many countries have implemented strict environmental and toxicological requirements. However, hormonal insecticides remain an important part of pest control in agriculture and forestry.

Resistance problem and new approaches

Since the 2010s, it has become evident that hormonal insecticides, like other chemical agents, are subject to resistance problems in insects. Many pest species have adapted to these products, reducing their effectiveness. Resistance has become a major topic for researchers, and many studies have been focused on solving this issue.

One approach that has been actively developed is the creation of insecticides with more specific actions to avoid destructive effects on ecosystems. Specifically, new molecules and combinations of substances have been developed to activate hormonal processes only in certain insect species, without affecting others.

Another solution has been the combined use of hormonal insecticides with other protection methods, such as biological agents or integrated pest management techniques. This approach has allowed for reduced chemical use while maintaining high effectiveness in plant protection.

Classification

Hormonal insecticides are classified based on various criteria, including the type of hormone used, the mechanism of action, and the spectrum of activity. The main groups of hormonal insecticides include:

• Moloskinal: synthetic juvenile hormone analog, used to prevent the proper development of insects.
• Lyroil: hormonal insecticide affecting metamorphosis, causing developmental disorientation in larvae.
• Tripectanil: insecticide mimicking ecdysteroids, disrupting molting and metamorphosis processes.
• Virfenfuron: synthetic effectin analog, used to control pests by disrupting their hormonal balance.
• Depenrol: hormonal insecticide affecting reproductive processes in insects, reducing their ability to reproduce.

Each of these groups has unique properties and mechanisms of action, making them suitable for different conditions and for various crops.

Mechanism of action

How insecticides affect the nervous system of insects

• Hormonal insecticides affect the nervous system of insects by modulating hormonal signals that control development and metamorphosis. These insecticides mimic or block the actions of natural hormones, such as juvenile hormone and ecdysteroids, leading to the disruption of normal growth and development processes in insects.

Impact on insect metabolism

• Disruption of hormonal signals leads to breakdowns in metabolic processes such as feeding, reproduction, and movement. This reduces the activity and vitality of pests, effectively controlling their populations and preventing damage to plants.

Examples of molecular mechanisms of action

• Hormonal insecticides, such as moloskinal, bind to juvenile hormone receptors, blocking its action and preventing normal larval development. Other insecticides, such as tripectanil, mimic ecdysteroid action, causing disruptions in the molting and transformation processes. These molecular mechanisms ensure high effectiveness of hormonal insecticides against various insect pests.

Difference between contact and systemic action

• Hormonal insecticides can have either contact or systemic action. Contact hormonal insecticides act directly when they come into contact with insects, penetrating through the cuticle or respiratory pathways and causing local disruptions in hormonal balance. Systemic hormonal insecticides penetrate plant tissues and spread throughout all parts, providing long-term protection from pests that feed on various plant parts. Systemic action allows for the control of pests over a longer period and in a wider application range.

Examples of products in this group

Moloskinal

• Mechanism of action: synthetic juvenile hormone analog, blocks normal larval development.
• Examples of products: moloskinal-250, agromolos, juvenil.
• Advantages: high efficiency against larvae, low toxicity to mammals, systemic action.
• Disadvantages: toxicity to beneficial insects, possible resistance development, environmental risk.

Lyroil

• Mechanism of action: affects metamorphosis, causing developmental disorientation in insects.
• Examples of products: lyroil-150, agrolyro, metamorphozin.
• Advantages: effective against a wide range of pests, systemic action, low toxicity to mammals.
• Disadvantages: toxicity to bees and other beneficial insects, potential soil and water contamination, resistance development.

Tripectanil

• Mechanism of action: mimics ecdysteroids, disrupting molting and metamorphosis.
• Examples of products: tripectanil-200, agripect, ecdysterol.
• Advantages: high efficacy against larvae and pupae, systemic action, low toxicity to mammals.
• Disadvantages: toxicity to beneficial insects, potential accumulation in soil and water, resistance development.

Virfenfuron

• Mechanism of action: synthetic effectin analog, disrupts the hormonal balance of insects.
• Examples of products: virfenfuron-100, agrovirfen, effectofuron.
• Advantages: broad spectrum of action, high stability, systemic action.
• Disadvantages: toxicity to bees and other beneficial insects, potential environmental contamination, resistance development.

Depenrol

• Mechanism of action: affects reproductive processes, reducing insect reproduction ability.
• Examples of products: depenrol-50, agropen, reproductol.
• Advantages: effective for long-term population control, low toxicity to mammals, systemic action.
• Disadvantages: toxicity to beneficial insects, potential accumulation in soil and water, resistance development.

Hormonal insecticides and their impact on the environment

Impact on beneficial insects

• Hormonal insecticides are toxic to beneficial insects, including bees, wasps, and other pollinators, as well as predatory insects that naturally control pest populations. This leads to reduced biodiversity and disruption of ecosystem balance, negatively impacting agricultural productivity and biodiversity.

Residual insecticide levels in soil, water, and plants

• Hormonal insecticides can accumulate in the soil for long periods, especially under high humidity and temperature conditions. This leads to the contamination of water sources through runoff and infiltration. In plants, hormonal insecticides are distributed throughout all parts, including leaves, stems, and roots, which promotes systemic protection but also results in the accumulation of insecticides in food products and soil, potentially affecting human and animal health.

Photostability and decomposition of insecticides in nature

• Many hormonal insecticides have high photostability, which increases their environmental persistence. This prevents rapid decomposition of insecticides under sunlight and contributes to their accumulation in soil and aquatic ecosystems. The high resistance to decomposition complicates the removal of hormonal insecticides from the environment and increases the risk of their impact on non-target organisms.

Biomagnification and accumulation in food chains

• Hormonal insecticides can accumulate in the bodies of insects and animals, transferring through the food chain and causing biomagnification. This leads to higher concentrations of insecticides at higher trophic levels, including predators and humans. Biomagnification of hormonal insecticides creates serious ecological and health issues, as accumulated insecticides can cause chronic poisoning and health disorders in animals and humans.

Insect resistance to insecticides

Causes of resistance

• Resistance in insects to hormonal insecticides is caused by genetic mutations and selection of resistant individuals through repeated use of the insecticide. Frequent and uncontrolled use of hormonal insecticides accelerates the spread of resistant genes among pest populations. Insufficient adherence to dosages and application schedules also speeds up the development of resistance, making the insecticide less effective.

Examples of resistant pests

• Resistance to hormonal insecticides has been observed in various species of insect pests, including whiteflies, aphids, moths, and some beetles. These pests show reduced sensitivity to insecticides, making them harder to control and leading to the need for more expensive and toxic products or a switch to alternative control methods.

Methods to prevent resistance

• To prevent the development of resistance to hormonal insecticides in insects, it is necessary to use insecticide rotation with different modes of action, combine chemical and biological control methods, and apply integrated pest management strategies. It is also important to follow recommended dosages and application schedules to avoid selecting resistant individuals and maintain the effectiveness of products in the long term.

Safety application guidelines

Preparation of solutions and dosages

• Proper preparation of solutions and precise dosing of insecticides are critical for effective and safe use of hormonal insecticides. It is essential to strictly follow the manufacturer's instructions for preparing solutions and dosing to avoid overdosing or inadequate treatment of plants. Using measuring tools and quality water helps ensure the accuracy of dosage and treatment efficiency.

Use of protective gear when working with insecticides

• When working with hormonal insecticides, appropriate protective gear, such as gloves, masks, goggles, and protective clothing, should be used to minimize the risk of exposure to the insecticide on the human body. Protective gear helps prevent contact with the skin and mucous membranes, as well as inhalation of toxic insecticide fumes.

Recommendations for plant treatment

• Apply hormonal insecticides to plants during morning or evening hours to avoid exposure to pollinators, such as bees. Avoid application during hot and windy weather, as this may cause the insecticide to spread and contaminate beneficial plants and organisms. It is also recommended to consider the plant's growth phase, avoiding treatment during active flowering and fruiting stages.

Adhering to waiting periods before harvesting

• Adhering to recommended waiting periods before harvesting after the application of hormonal insecticides ensures the safety of consumption and prevents insecticide residues from entering food products. It is important to follow the manufacturer's instructions regarding waiting times to avoid poisoning risks and ensure product quality.

Alternatives to chemical insecticides

Biological insecticides

• Using entomophages, bacterial, and fungal preparations provides an environmentally safe alternative to chemical insecticides. Biological insecticides, such as bacillus thuringiensis, effectively control insect pests without harming beneficial organisms and the environment. These methods contribute to sustainable pest management and biodiversity conservation.

Natural insecticides

• Natural insecticides, such as neem oil, tobacco infusions, and garlic solutions, are safe for plants and the environment for controlling pests. These products have repellent and insecticidal properties, allowing for effective insect population control without synthetic chemicals. Natural insecticides can be used in combination with other methods for the best results.

Pheromone traps and other mechanical methods

• Pheromone traps attract and destroy insect pests, reducing their numbers and preventing spread. Other mechanical methods, such as sticky surface traps and barriers, also help control pest populations without chemical use. These methods are effective and environmentally safe for pest management.

Examples of most popular insecticides in this group

Moloskinal

• Active ingredient: moloskinal
• Mechanism: binds with juvenile hormone, blocking normal larval development
• Application: vegetable crops, fruit trees
• Products: moloskinal-250, agromolos, juvenil

Lyroil

• Active ingredient: lyroil
• Mechanism: affects metamorphosis, causing disorientation in insect development
• Application: vegetable and fruit crops, horticulture
• Products: lyroil-150, agrolyro, metamorphozin

Tripectanil

• Active ingredient: tripectanil
• Mechanism: mimics ecdysteroids, disrupting molting and metamorphosis
• Application: vegetable and fruit crops, ornamental plants
• Products: tripectanil-200, agripect, ecdysterol

Virfenfuron

• Active ingredient: virfenfuron
• Mechanism: disrupts hormonal balance, causing paralysis and death of pests
• Application: vegetable, fruit, and ornamental crops
• Products: virfenfuron-100, agrovirfen, effetofuron

Depenrol

• Active ingredient: depenrol
• Mechanism: affects reproductive processes, reducing insect reproduction ability
• Application: vegetable and fruit crops, horticulture
• Products: depenrol-50, agropen, reproductol

Advantages and disadvantages

• Advantages
  • High effectiveness against a wide range of insect pests
  • Specificity of action, minimal impact on mammals
  • Systemic distribution in the plant, providing long-term protection
  • Low toxicity to beneficial insects when applied correctly
• Disadvantages
  1. Toxicity to beneficial insects, including bees and wasps
  2. Potential development of resistance in insect pests
  3. Possible contamination of soil and water sources
  4. Higher cost of some products compared to traditional insecticides

Risks and precautions

• Impact on human and animal health hormonal insecticides can significantly affect human and animal health if used improperly. When ingested, they can cause symptoms of poisoning, such as dizziness, nausea, vomiting, headaches, and in severe cases, seizures and loss of consciousness. Animals, especially pets, are also at risk of poisoning if the insecticide comes into contact with their skin or if they ingest treated plants.
• Symptoms of poisoning symptoms of hormonal insecticide poisoning include dizziness, headaches, nausea, vomiting, weakness, difficulty breathing, seizures, and loss of consciousness. If the insecticide comes into contact with the eyes or skin, irritation, redness, and burning may occur. In case of ingestion, seek medical attention immediately.
• First aid for poisoning if poisoning with hormonal insecticides is suspected, stop contact with the insecticide immediately, rinse affected skin or eyes with plenty of water for at least 15 minutes. If inhaled, move to fresh air and seek medical help. If ingested, call emergency services and follow first aid instructions provided on the product packaging.

Pest prevention

• Alternative pest control methods cultural methods such as crop rotation, mulching, removing infected plants, and introducing resistant varieties help prevent pest emergence and reduce the need for insecticides. These methods create unfavorable conditions for insect pests and strengthen plant health. Biological control methods, including the use of entomophages and other natural insect predators, are also effective prevention tools.
• Creating unfavorable conditions for pests proper watering, removal of fallen leaves and plant debris, and maintaining garden cleanliness create unfavorable conditions for pest reproduction and spread. Installing physical barriers such as nets and borders helps prevent pests from reaching plants. Regular plant inspection and timely removal of damaged parts also reduce plants' attractiveness to pests.

Conclusion

The rational use of hormonal insecticides plays an important role in plant protection and increasing the yield of agricultural and ornamental plants. However, it is essential to follow safety regulations and consider environmental aspects to minimize negative impacts on the environment and beneficial organisms. An integrated pest

Management approach, combining chemical, biological, and cultural control methods, promotes sustainable agricultural development and biodiversity conservation. It is also crucial to continue researching new insecticides and control methods to reduce risks to human health and ecosystems.

Frequently asked questions (FAQ)

• What are hormonal insecticides and what are they used for?

Hormonal insecticides are chemicals that mimic or disrupt hormonal processes in insect organisms. They are used to manage pest insect populations by interfering with their development, metamorphosis, and reproductive functions.

• How do hormonal insecticides affect the nervous system of insects?

Hormonal insecticides affect the nervous system of insects by modulating hormonal signals responsible for development and metamorphosis. This leads to the continuous activation of nerve impulses, paralysis, and death of insects.

• Are hormonal insecticides harmful to beneficial insects, such as bees?

Yes, hormonal insecticides are toxic to beneficial insects, including bees and wasps. Their use requires strict adherence to regulations to minimize the impact on beneficial insects.

• How can we prevent resistance development in insects to hormonal insecticides?

To prevent resistance, it is necessary to rotate insecticides with different modes of action, combine chemical and biological control methods, and adhere to recommended dosages and application schedules.

• What ecological issues are associated with the use of hormonal insecticides?

The use of hormonal insecticides leads to reduced populations of beneficial insects, soil and water contamination, and accumulation of insecticides in food chains, causing serious ecological and health problems.

• Can hormonal insecticides be used in organic farming?

No, hormonal insecticides do not meet the requirements for organic farming due to their synthetic nature and potential negative impact on the environment and beneficial organisms.

• How should hormonal insecticides be applied for maximum effectiveness?

It is necessary to strictly follow the manufacturer's instructions for dosage and application, treat plants during morning or evening hours, avoid treatment during pollinator activity, and ensure uniform distribution of the insecticide over the plants.

• Are there alternatives to hormonal insecticides for pest control?

Yes, there are biological insecticides, natural remedies (neem oil, garlic solutions), pheromone traps, and mechanical control methods that can be used as alternatives to hormonal insecticides.

• How can the environmental impact of hormonal insecticides be minimized?

Use the insecticide only when necessary, follow recommended dosages and application schedules, avoid contaminating water sources, and apply integrated pest management methods to reduce reliance on chemical agents.

• Where can hormonal insecticides be purchased?

Hormonal insecticides are available at specialized agricultural stores, online shops, and plant protection suppliers. Before purchasing, ensure the legality and safety of the products used.