Insecticides affecting insect growth and development

Insecticides affecting the growth and development of insects are a class of chemical substances designed to disrupt biological processes related to growth, metamorphosis, and reproductive functions in pest insects. These insecticides interfere with hormonal regulation and cellular mechanisms, leading to developmental delay, morphogenesis disorders, and reduced reproductive capabilities. As a result, the application of such insecticides leads to a reduction in pest populations, contributing to the protection of agricultural crops and ornamental plants.

Goals and importance in agriculture and horticulture

The primary goal of using insecticides that affect insect growth and development is to effectively control pest populations, thereby increasing crop yields and product quality. In agriculture, these insecticides are used to protect cereal crops, vegetables, fruits, and other agricultural plants from pests such as aphids, whiteflies, fruit flies, and others. In horticulture, they are employed to protect ornamental plants, fruit trees, and shrubs, maintaining their health and aesthetic appeal. Due to their specificity and focus on the biological processes of insects, growth- and development-affecting insecticides are an important component of integrated pest management (ipm), ensuring sustainable and effective agriculture.

Relevance of the topic

Given the growth of the global population and increasing food demands, effective pest management has become critically important. Insecticides that affect growth and development offer innovative approaches to pest control, reducing the need for more toxic chemical agents. However, improper use of these insecticides can lead to the development of resistance in pests and negative ecological consequences, such as reduced populations of beneficial insects and environmental contamination. Therefore, studying the mechanisms of action, ecosystem impact, and developing sustainable application methods are important aspects of modern agrochemistry.

History

Insecticides that affect insect growth and development form a distinct group of chemicals that disrupt the normal development of insects by preventing their transformation from larvae to pupae and from pupae to adults. These insecticides affect the hormonal system of insects, interfering with processes that regulate their metamorphosis and development. This group of insecticides is used to control pest populations at different stages of their life cycle and is applied in agriculture, horticulture, and pest control.

1. Early research and discoveries

the development of insecticides affecting insect growth and development began in the 1940s. Initially, scientists attempted to use hormonal substances that could affect the metamorphosis of insects, thus preventing their development. These substances were typically synthetic analogs of hormones that control molting and metamorphosis in insects.

2. 1950–1960s: the beginning of hormonal drug application

the first hormonal insecticides began to be developed in the mid-20th century. Drugs that disrupted hormonal processes in insects affected molting by interrupting larval development and preventing transition to the pupal stage. One of the first such drugs was aldrin, which was used to control pest populations, but its use led to environmental problems, such as long-term accumulation in the soil.
Example:

• Kallochem (1960s) – a synthetic insecticide that disrupted hormone synthesis in insects and affected their metamorphosis. Kallochem was used to combat pests but was quickly replaced by more effective agents.

3. 1970–1980s: development of a new generation of insecticides

during this period, new chemical compounds based on hormonal insecticides aimed at disrupting metamorphosis were developed. These compounds had a more targeted effect on the developmental stages of insects. Some of them affected hormone synthesis, stimulating abnormal molting or complete molting failure.
Example:

• Teflubenzuron (1980s) – an insecticide that affects the synthesis of chitinizing hormones, blocking the molting process in insects. This drug was actively used to control pests in agriculture, especially to protect crops from insects that damage plants in the larval stage.

4. 1990s: increased efficiency and reduced toxicity

with the development of the chemical industry in the 1990s, insecticides were created that acted even more selectively, minimizing the impact on other organisms and increasing efficacy against pests. These agents were used not only to combat pests at early developmental stages but also to protect agricultural crops during periods of maximum vulnerability.
Example:

• Loveness (1990s) – a synthetic compound that influences hormonal regulation in insects, leading to developmental disruption. It is especially effective against pests in the larval stage.

5. Modern trends: innovations and new molecules

modern insecticides affecting the growth and development of insects continue to evolve to provide more specific impacts and minimize environmental harm. In recent decades, scientists have been working on creating new molecules that will be more resistant to external factors and offer more precise effects on insect metamorphosis.
Example:

• Fenoxycarb (2000s) – a modern insecticide that disrupts insect metamorphosis, used to control pests in agriculture and horticulture. Fenoxycarb is effective against a number of insects by disrupting their development during the larval stage.

Problems of resistance and innovations

• The development of resistance in insects to growth- and development-affecting insecticides has become one of the main problems associated with their use. Pests exposed to repeated applications of these insecticides may evolve and become less susceptible to their effects. This requires the development of new insecticides with different mechanisms of action and the implementation of sustainable control methods, such as rotating insecticides and using combined preparations. Modern research focuses on creating insecticides with improved properties that help reduce the risks of resistance development and minimize ecological impact.

Classification

Insecticides affecting the growth and development of insects are classified based on different criteria, including chemical composition, mechanism of action, and spectrum of activity. The main groups of insecticides in this category include:

• Moluskinals: synthetic analogs of juvenile hormones used to prevent normal development of insect larvae.
• Ecdysteroids: insecticides that mimic the action of ecdysteroids, hormones that regulate metamorphosis in insects.
• Hormonal inhibitors: compounds that block the action of natural hormones such as metabolic hormones and growth hormones.
• Insecticides affecting mutational processes: agents that disrupt genetic material in insects, hindering normal growth and development.
• Synthetic bioactive compounds: modern insecticides developed from natural substances with enhanced efficacy and safety profiles.

Each of these groups has unique properties and mechanisms of action, allowing them to be used in various conditions and to control different types of insect pests.

Insecticides affecting the growth and development of insects are a specialized group of plant protection products that disrupt the physiological processes of insects, preventing their normal development, metamorphosis, or reproduction. These products do not always kill the insect directly but can suppress its vital functions at various stages of development, leading to the cessation of growth, death of larvae, or the inability to complete metamorphosis.

1. Insecticides acting on metamorphosis
These insecticides interfere with the normal physiological processes associated with the transformation of insects from larvae to pupae and from pupae to adult forms. This occurs by suppressing or distorting the synthesis of hormones that regulate insect development.

1.1. Insecticides affecting ecdysteroid hormones

Ecdysteroids are hormones that control the process of molting and metamorphosis in insects. Insecticides in this group interfere with the synthesis of these hormones, disrupting the molting process and the transformation of larvae into more mature forms.

Examples:

• Chlorfenapyr — affects the synthesis of ecdysteroids, disrupting insect molting.
• Sfenodon — blocks the action of ecdysteroids, preventing normal metamorphosis.

1.2. Insecticides affecting juvenile hormone

Juvenile hormone controls the development of insects during their larval stage. Some insecticides block the synthesis or action of this hormone, preventing the insect from developing into an adult.

Examples:

• Methoprene — inhibits the action of juvenile hormone, leading to developmental disruptions in larvae.
• Propioconazole — disrupts the synthesis of juvenile hormone, hindering the transformation of larvae into imagos.

2. Insecticides acting on feeding and growth

These products affect the metabolism of insects, disrupting their ability to properly digest food and absorb nutrients. This can lead to stunted growth, exhaustion, or death.

2.1. Insecticides disrupting protein synthesis
Some insecticides block protein synthesis in the insect's body, slowing down their growth and development, and causing death during the larval stage.

Examples:

• Selesol — prevents protein synthesis, disrupting the normal growth of insects.
• Pyriproxyfen — affects protein metabolism, slowing growth and development.

2.2. Insecticides blocking food absorption

These insecticides affect digestion, preventing the absorption of nutrients, which slows down insect growth and leads to starvation.

Examples:

• Tramcarb — affects carbohydrate and protein metabolism, reducing food absorption.
• Lambda-cyhalothrin — blocks enzymes necessary for food digestion.

3. Insecticides disrupting reproduction

Some insecticides affect the reproductive organs of insects, disrupting their ability to reproduce. These products may either block the development of gametes or interfere with the action of sex hormones, leading to an inability to reproduce.

3.1. Insecticides affecting hormones regulating reproduction

These insecticides block or disrupt the production of hormones responsible for the development of gametes in insects.

Examples:

• Acetamiprid — disrupts the production of hormones regulating reproduction.
• Moxifene — blocks the action of reproductive hormones, preventing mating and reproduction.

3.2. Insecticides affecting reproductive organs

These insecticides directly affect the reproductive organs of insects, blocking their normal development and function.

Examples:

• Resamet — affects the reproductive organs, preventing their development.
• Oxidophen — disrupts the function of the gonads in insects, inhibiting their ability to reproduce.

4. Insecticides affecting the nervous system and growth

Some insecticides not only block the development of insects but also affect their nervous system, disrupting not only growth but also behavior.

4.1. Insecticides affecting the nervous system

These products may block the transmission of nerve impulses, affecting the coordination of insect movements, their ability to search for food, and reproduce.

Examples:

• Pyrethroids (e.g., permethrin) — affect the nervous system, causing paralysis in insects.
• Fipronil — disrupts nerve impulse transmission and slows down insect growth.

Mechanism of action

How insecticides affect the nervous system of insects

• Insecticides affecting the growth and development of insects affect the nervous system indirectly by disrupting biological processes related to growth and metamorphosis. For example, moluskinals and hormonal inhibitors interfere with hormonal regulation, leading to disrupted nerve impulse transmission and muscle contraction. Ecdysteroids, which mimic natural hormones, disrupt normal metamorphosis processes, also affecting the nervous system, causing paralysis and death of insects.

Impact on insect metabolism

• Disruption of hormonal regulation and metamorphosis leads to failure in metabolic processes such as feeding, growth, and reproduction. This reduces the level of adenosine triphosphate (atp), decreasing the energy required for nervous system and muscle function. As a result, insects become less active, their ability to feed and reproduce is diminished, which reduces pest populations and prevents damage to plants.

Examples of molecular mechanisms of action

• Inhibition of acetylcholinesterase: some insecticides block acetylcholinesterase activity, causing an accumulation of acetylcholine in the synaptic cleft and disrupting nerve impulse transmission.
• Blocking sodium channels: pyrethroids and neonicotinoids block sodium channels in nerve cells, causing continuous excitation of nerve impulses and paralysis of muscles.
• Modulation of hormonal receptors: ecdysteroids and hormonal inhibitors interact with hormonal receptors, disrupting normal growth and metamorphosis regulation, leading to abnormal development and insect death.
• Disruption of genetic processes: insecticides affecting mutational processes cause dna and rna damage, preventing normal cell growth and insect development.

Difference between contact and systemic action

• Insecticides affecting the growth and development of insects can have both contact and systemic action. Contact insecticides act directly when insects come into contact with them, penetrating through the cuticle or respiratory system and causing localized disruptions in hormonal regulation and metabolism. Systemic insecticides penetrate plant tissues and spread throughout all parts of the plant, providing long-term protection against pests feeding on different plant parts. Systemic action allows for longer-term pest control and is effective over a wide application area, ensuring effective protection for crops.

Examples of products in this group

Moluskinals

• Mechanism of action: synthetic analogs of juvenile hormones, blocking the normal development of insect larvae.
• Examples:
  • Moluskin-250
  • Rostopal
  • Juvenil

Ecdysteroids

• Mechanism of action: mimics the action of ecdysteroids, disrupting molting and metamorphosis processes.
• Examples:
  • Pyritrox
  • Ecdisterol
  • Metamorphosin

Hormonal inhibitors

• Mechanism of action: blocks the action of natural growth and metamorphosis hormones, disrupting normal insect development.
• Examples:
  • Hormonal
  • Inhibium
  • Regulit

Insecticides affecting mutational processes

• Mechanism of action: disrupts genetic processes like dna and rna synthesis, hindering normal growth and development.
• Examples:
  • Genotyp
  • Mutacid
  • Dna-spar

Synthetic bioactive compounds

• Mechanism of action: developed from natural substances with specific action mechanisms targeting insect growth and development biological processes.
• Examples:
  • Biogrow
  • Actaxis
  • Sintophyt

Environmental impact of growth- and development-affecting insecticides (continued)

Impact on beneficial insects

• Insecticides that affect the growth and development of insects can have toxic effects on beneficial insects, including bees, wasps, and other pollinators, as well as predatory insects that naturally control pest populations. This can lead to a reduction in biodiversity and the disruption of ecological balance, negatively affecting agricultural productivity and biodiversity. The impact of insecticides on pollinators is especially dangerous, as it can reduce crop yields and product quality.

Residual insecticide levels in soil, water, and plants

• Insecticides that affect insect growth and development can accumulate in the soil for extended periods, especially under conditions of high humidity and temperature. This can lead to contamination of water sources through runoff and infiltration. In plants, insecticides are distributed across all parts, including leaves, stems, and roots, providing systemic protection but also resulting in insecticide buildup in food products and soil. This accumulation can negatively impact the health of humans and animals.

Photostability and degradation of insecticides in nature

• Many insecticides affecting insect growth and development are highly photostable, which extends their persistence in the environment. This prevents the rapid degradation of insecticides under the influence of sunlight and contributes to their accumulation in soil and aquatic ecosystems. High resistance to degradation complicates the removal of insecticides from the environment and increases the risk of their impact on non-target organisms.

Biomagnification and accumulation in food chains

• Insecticides that affect growth and development can accumulate in the bodies of insects and animals, moving up the food chain and causing biomagnification. This leads to higher concentrations of insecticides at the upper levels of the food chain, including predators and humans. Biomagnification of insecticides causes serious ecological and health issues, as accumulated insecticides may lead to chronic poisoning and health problems in animals and humans.

The problem of insect resistance to insecticides

Causes of resistance development

• The development of resistance in insects to insecticides affecting growth and development is driven by genetic mutations and the selection of resistant individuals during repeated applications of insecticides. Frequent and uncontrolled use of insecticides leads to the rapid spread of resistant genes among pest populations. Inadequate adherence to recommended dosages and application schedules also accelerates the resistance development process, making the insecticide less effective. Additionally, the prolonged use of the same mechanism of action contributes to the selection of resistant insects and reduces the overall effectiveness of pest control.

Examples of resistant pests

• Resistance to insecticides affecting growth and development has been observed in various pest species, including whiteflies, aphids, mites, and some moth species. For example, resistance to moluskinals has been recorded in certain populations of aphids and whiteflies, making their control more difficult and leading to the need for more expensive and toxic agents or the transition to alternative control methods. Resistance development has also been observed in some colorado beetle species, increasing the challenges in controlling this pest and requiring more complex approaches.

Methods to prevent resistance

• To prevent the development of resistance in insects to insecticides affecting growth and development, it is necessary to use a rotation of insecticides with different mechanisms of action, combine chemical and biological control methods, and apply integrated pest management strategies. It is also important to strictly follow recommended dosages and application schedules to avoid the selection of resistant individuals and maintain the effectiveness of insecticides in the long term. Additional measures include the use of mixed formulations, implementing cultural methods to reduce pest pressure, and using biological controllers to maintain ecological balance.

Guidelines for safe application of insecticides

Preparation of solutions and dosages

• Proper preparation of solutions and precise dosage of insecticides affecting growth and development is critical for effective and safe application. It is essential to strictly follow the manufacturer's instructions for mixing solutions and dosing to avoid overdosing or insufficient treatment of plants. The use of measuring tools and quality water ensures dosing accuracy and treatment effectiveness. It is recommended to conduct trials on small plots before large-scale application of insecticides to determine optimal conditions and dosages.

Use of protective equipment when handling insecticides

• When working with insecticides that affect growth and development, appropriate protective gear, such as gloves, masks, goggles, and protective clothing, should be used to minimize the risk of insecticide exposure to humans. Protective equipment helps prevent contact with the skin and mucous membranes, as well as inhalation of toxic fumes from insecticides. Additionally, safety precautions should be followed when storing and transporting insecticides to avoid accidental exposure to children and pets.

Recommendations for plant treatment

• When treating plants with insecticides that affect growth and development, it is best to apply them during the early morning or evening hours to avoid exposure to pollinators such as bees. Avoid treatment during hot and windy weather, as this may cause insecticide spray drift and contamination of beneficial plants and organisms. It is also recommended to consider the growth stage of the plants, avoiding application during active flowering and fruiting periods to minimize the impact on pollinators and reduce the risk of insecticide residue on fruits and seeds.

Compliance with waiting periods before harvesting

• Adhering to recommended waiting periods before harvesting after applying insecticides that affect growth and development ensures the safety of consumption and prevents insecticide residues from entering food products. It is important to follow the manufacturer's instructions for waiting periods to avoid the risk of poisoning and to ensure the quality of the produce. Failure to comply with waiting periods can lead to the accumulation of insecticides in food products, negatively affecting the health of humans and animals.

Alternatives to chemical insecticides

Biological insecticides

• The use of entomophages, bacterial, and fungal agents provides an ecologically safe alternative to chemical insecticides that affect growth and development. Biological insecticides, such as bacillus thuringiensis and beauveria bassiana, effectively control insect pests without harming beneficial organisms or the environment. These methods promote sustainable pest management and biodiversity conservation, reducing the need for chemical agents and minimizing the ecological footprint of agricultural practices.

Natural insecticides

• Natural insecticides, such as neem oil, tobacco infusions, and garlic solutions, are safe for plants and the environment and provide effective pest control. These substances have repellent and insecticidal properties, allowing for the control of insect populations without synthetic chemicals. Neem oil, for example, contains azadirachtin and nimbolide, which interfere with insect feeding and growth, causing paralysis and death. Natural insecticides can be used in combination with other methods to achieve the best results and reduce the risk of resistance development in insect pests.

Pheromone traps and other mechanical methods

• Pheromone traps attract and destroy insect pests, reducing their numbers and preventing their spread. Pheromones are chemical signals used by insects for communication, such as for attracting mates. The use of pheromone traps allows for targeted control of specific pest species without affecting non-target organisms. Other mechanical methods, such as sticky surface traps, barriers, and physical nets, also help control pest populations without the use of chemicals. These methods are effective and environmentally safe, promoting biodiversity conservation and ecological balance.

Examples of popular insecticides from this group

Product name	Active ingredient	Mechanism of action	Application area
Moluskin	Moluskinal	Blocks juvenile hormone, preventing normal larval development	Vegetable crops, fruit trees
Ecdisterol	Ecdisterol	Mimics ecdysteroids, disrupting molting and metamorphosis processes	Vegetable and fruit crops, horticulture
Regulit	Regulit	Blocks hormonal receptors, disrupting growth and metamorphosis	Vegetable crops, ornamental plants
Genotyp	Genotyp	Disrupts dna and rna synthesis, preventing cellular growth	Vegetable crops, cereals, fruits
Biogro	Biogro	Synthetic bioactive compounds targeting hormonal processes	Vegetable and fruit crops, ornamental plants
Actaxis	Actaxis	Synthetic bioactive compounds affecting metamorphosis	Vegetable crops, horticulture
Bacillus thuringiensis (bt)	Bacillus thuringiensis	Produces cry proteins that destroy insect intestines	Vegetable crops, fruit trees
Bacillus bassiana	Beauveria bassiana	Fungi that parasitize insects, destroying their intestines	Vegetable and fruit crops, horticulture
Imidacloprid	Imidacloprid	Binds to nicotinic acetylcholine receptors, stimulating the nervous system	Vegetable and fruit crops, ornamental plants
Methomyl	Methomyl	Inhibits acetylcholinesterase, causing acetylcholine accumulation and paralysis	Cereal crops, vegetables, fruits

Advantages and disadvantages

Advantages

• High effectiveness against a wide range of insect pests
• Specific action with minimal impact on mammals
• Ability to control various developmental stages of insects
• Can be combined with other control methods for enhanced efficacy
• Rapid action leading to quick pest population reduction
• Systemic distribution in plants providing long-term protection

Disadvantages

• Toxicity to beneficial insects, including bees and wasps
• Potential development of resistance in insect pests
• Possible contamination of soil and water sources
• High cost of some insecticides compared to traditional methods
• Need for strict adherence to dosages and application schedules to avoid negative consequences
• Limited spectrum of activity for some insecticides

Risks and precautionary measures

Impact on human and animal health

• Insecticides affecting insect growth and development can have serious effects on 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 when insecticide comes into contact with their skin or if they ingest treated plants.

Symptoms of poisoning with insecticides

• Symptoms of poisoning from insecticides affecting growth and development include dizziness, headaches, nausea, vomiting, weakness, difficulty breathing, seizures, and loss of consciousness. When insecticide comes into contact with eyes or skin, irritation, redness, and burning sensations may occur. If insecticide is ingested, immediate medical attention should be sought.

First aid for poisoning

• In case of suspected poisoning by insecticides affecting growth and development, contact with the insecticide should be stopped immediately, and affected skin or eyes should be flushed with plenty of water for at least 15 minutes. If inhaled, move to fresh air and seek medical attention. If insecticide is ingested, call emergency services and follow the first aid instructions on the product label.

Conclusion

The rational use of insecticides affecting insect growth and development plays a crucial role in plant protection and enhancing crop yields in agriculture and ornamental plant cultivation. However, safety guidelines must be followed, and environmental considerations taken into account to minimize the negative impact on the environment and beneficial organisms. An integrated approach to pest management, combining chemical, biological, and cultural control methods, supports sustainable agricultural development and biodiversity conservation. Continued research on the development of new insecticides and control methods is also important to reduce health risks to humans and ecosystems.

Frequently asked questions (FAQ)

1. What are insecticides affecting growth and development, and what are they used for?
   Insecticides affecting growth and development are a class of chemicals designed to disrupt biological processes related to growth, metamorphosis, and reproductive functions in pest insects. They are used to control insect populations, improve yields, and prevent damage to agricultural and ornamental plants.
2. How do insecticides affecting growth and development impact the insect nervous system?
   These insecticides affect the nervous system of insects indirectly by disrupting hormonal regulation and metamorphosis, which impairs nerve impulse transmission and muscle contraction. As a result, insects become less active, leading to paralysis and death.
3. Are insecticides affecting growth and development harmful to beneficial insects like bees?
   Yes, insecticides affecting growth and development can be toxic to beneficial insects, including bees and wasps. Their use requires strict adherence to regulations to minimize impact on beneficial insects and prevent a reduction in biodiversity.
4. How can the development of resistance to growth and development insecticides be prevented?
   To prevent resistance, insecticides with different mechanisms of action should be rotated, chemical and biological control methods should be combined, and recommended dosages and application schedules should be followed. Integrated pest management strategies should also be implemented to reduce pest pressure.
5. What environmental problems are associated with the use of growth- and development-affecting insecticides?
   The use of these insecticides leads to a reduction in beneficial insect populations, contamination of soil and water, and the accumulation of insecticides in food chains, causing significant ecological and health problems.
6. Can growth- and development-affecting insecticides be used in organic farming?
   Some insecticides affecting growth and development may be allowed in organic farming, especially those based on natural microbes and plant extracts. However, synthetic insecticides typically do not meet organic farming standards due to their chemical origins and potential environmental impact.
7. How should growth- and development-affecting insecticides be applied for maximum effectiveness?
   It is important to strictly follow manufacturer instructions for dosage and application schedules, treat plants in the early morning or evening hours, avoid treatment during pollinator activity, and ensure even distribution of the insecticide on plants. Testing on small plots before large-scale application is recommended.
8. Are there alternatives to growth- and development-affecting insecticides for pest control?
   Yes, biological insecticides, natural remedies (neem oil, garlic solutions), pheromone traps, and mechanical control methods can serve as alternatives to chemical insecticides. These methods help reduce reliance on chemicals and minimize environmental impact.
9. How can the environmental impact of growth- and development-affecting insecticides be minimized?
   Use insecticides only when necessary, follow recommended dosages and application schedules, avoid contamination of water sources, and apply integrated pest management methods to reduce chemical dependence. It is also important to use insecticides with high specificity to minimize impact on non-target organisms.
10. Where can growth- and development-affecting insecticides be purchased?
    These insecticides are available at specialized agro-technical stores, online retailers, and plant protection suppliers. Before purchasing, ensure the legality and safety of the products and their compliance with organic or conventional farming standards.