Insecticides are an essential tool in pest management, and there are various types of insecticides available. Systemic and contact insecticides are two common types of insecticides that are used to control pests in different ways. Understanding the differences between these two types of insecticides is crucial in determining the most effective pest control strategy.
Systemic insecticides are designed to be absorbed by plants and move through their tissues, making them effective against pests that feed on plants. These insecticides are applied to the soil or foliage and are taken up by the plant’s roots or leaves. Once inside the plant, the insecticide moves through the vascular system and reaches all parts of the plant, including the leaves, stems, and roots. This makes systemic insecticides an excellent option for controlling pests that are difficult to reach with contact insecticides.
Contact insecticides, on the other hand, kill pests when they come into contact with the insecticide. These insecticides are applied directly to the pest or the plant’s surface, and they work by either suffocating or poisoning the pest. Contact insecticides are effective against pests that are visible and accessible, making them an excellent option for controlling pests that are on the plant’s surface. However, they may not be effective against pests that are hidden, such as those that feed on the plant’s interior.
Definition of Systemic Insecticide
Systemic insecticides are a type of pesticide that are designed to kill pests that feed on plants. These insecticides are absorbed by the plant and transported throughout its vascular system, including the phloem and xylem. This means that the insecticide is present in all parts of the plant, including the leaves, stems, and roots.
Systemic insecticides are typically applied as a spray or soil drench, and they are taken up by the plant’s roots and transported to the rest of the plant. Once the insecticide is present in the plant, it can kill pests that feed on the plant tissue, including aphids, mealybugs, and whiteflies.
Systemic insecticides are often preferred over contact insecticides because they provide longer-lasting control and are less likely to be washed off by rain or irrigation. Additionally, systemic insecticides can be effective against pests that are difficult to control with contact insecticides, such as those that feed on the undersides of leaves or inside plant tissues.
Definition of Contact Insecticide
Contact insecticide is a type of insecticide that kills pests when they come into direct contact with the insecticide. This type of insecticide works by affecting the nervous system of the insect, causing paralysis and death. Contact insecticides are often used to control crawling insects, such as ants and cockroaches, and flying insects, such as mosquitoes and flies.
Contact insecticides are usually sprayed directly onto the pests or applied to surfaces where the pests are likely to come into contact. They are effective in killing insects that are visible and accessible, but may not be effective against hidden or protected pests.
One advantage of contact insecticides is that they have a quick knockdown effect, meaning they can kill insects almost immediately upon contact. However, they may need to be reapplied frequently to maintain their effectiveness, especially in areas with high pest populations.
Mode of Action of Systemic Insecticide
Systemic insecticides are chemicals that can move through the vascular systems of plants and poison insects that feed on them, regardless of where they are applied. These insecticides are water-soluble and are taken up by a plant and transported throughout its body. The chemicals can thus be found in every part of the plant, including the leaves, roots, stems, fruits, flowers, and even the pollen and nectar.
Systemic insecticides are intended to kill via ingestion of plant tissue contaminated from the inside over time, while non-systemics are designed to kill via contact with or ingestion of surface residues shortly after application. Systemic insecticides are particularly useful in controlling pests that are difficult to reach with contact insecticides, such as those that are hidden in plant tissues or those that feed on the roots of plants.
Systemic insecticides can kill insects directly on contact or through the ingestion of treated plant tissue. Once the insects consume the treated plant tissue, the insecticide enters their bodies and disrupts their nervous system or other vital physiological processes, leading to their death. Some systemic insecticides can also inhibit the growth and development of insects, preventing them from reaching maturity or reproducing.
Systemic insecticides are classified based on their mode of action, which refers to the specific biochemical target or process that the insecticide affects in the insect’s body. The Insecticide Resistance Action Committee (IRAC) has developed a mode of action classification system to help farmers and pest control professionals choose the right insecticides and manage resistance effectively. The mode of action of systemic insecticides varies depending on the active ingredient, but most of them target the nervous system or other vital physiological processes of insects.
Mode of Action of Contact Insecticide
Contact insecticides are designed to kill insects when they come into direct contact with the insecticide. The active ingredients in contact insecticides are usually fast-acting and toxic to insects. When applied to plants or other surfaces, contact insecticides form a layer of protection that kills insects on contact.
The mode of action of contact insecticides varies depending on the type of active ingredient used. For example, pyrethroids disrupt the functioning of sodium channels in neuronal membranes, while organophosphates and carbamates increase cholinesterase inhibition. Contact insecticides can also affect aquatic biota via several different modes of action, and the mode of action can vary with the type of insecticide.
Contact insecticides are often used to control insects that are easily visible, such as aphids, whiteflies, and spider mites. They are also effective against flying insects, such as mosquitoes and flies. However, contact insecticides have some limitations. They do not provide long-term protection, and they are not effective against insects that feed on plant tissue, such as root-feeding insects and boring insects.
Overall, contact insecticides are a useful tool for controlling insect infestations, but they should be used in conjunction with other control methods, such as cultural practices and biological control agents. When using contact insecticides, it is important to follow the label instructions carefully and to use them only as directed to minimize the risk of environmental contamination and harm to non-target organisms.
Application of Systemic Insecticide
Systemic insecticides are applied to the soil, seed, or foliage of a plant, and are absorbed by the plant’s vascular system which includes the phloem and xylem. The movement of systemic insecticides takes place within the plant, and it can move throughout the entire plant including new shoots. This makes it an effective method of controlling pests that feed on plants.
When applying systemic insecticides, it is important to follow the manufacturer’s instructions carefully. The amount of insecticide applied will depend on the size of the plant, the type of insecticide being used, and the severity of the infestation.
Systemic insecticides can be applied as a soil drench, granular application, or foliar spray. Soil drenches are applied directly to the soil around the base of the plant and are absorbed by the roots. Granular applications are sprinkled over the soil surface and are absorbed by the roots when watered in. Foliar sprays are applied directly to the leaves and are absorbed through the stomata.
It is important to note that systemic insecticides can take time to move up to the new shoots and control doesn’t happen until the toxic material is present where the insects or mites are feeding. Therefore, it may take several days or even weeks for the full effects of the insecticide to be seen.
When using systemic insecticides, it is important to take precautions to avoid harming non-target organisms such as bees and other beneficial insects. It is also important to rotate the use of insecticides to prevent the development of resistance in pest populations.
Application of Contact Insecticide
Contact insecticides are used to kill pests when they come into contact with the insecticide. They are applied directly to the surface of the plant or the soil to control insects and mites that are present on the surface. Contact insecticides are generally used for controlling pests that are visible and accessible, such as aphids, whiteflies, and spider mites. They are also used for spot treatments, such as treating ant hills or individual plants that are infested with pests.
Contact insecticides can be applied using different methods, such as spraying, dusting, or drenching. Spraying is the most common method, and it involves applying the insecticide as a fine mist using a sprayer. Dusting involves applying the insecticide as a powder using a duster. Drenching involves applying the insecticide as a liquid directly to the soil around the plant.
Contact insecticides have a short residual activity, which means that they only provide protection for a short period of time. They are not absorbed by the plant, so they do not provide long-lasting protection. Contact insecticides are also more likely to harm beneficial insects, such as bees and ladybugs, because they are applied directly to the surface of the plant.
When using contact insecticides, it is important to follow the label instructions carefully. Wear protective clothing, such as gloves and a mask, and avoid applying the insecticide on windy days to prevent drift. It is also important to avoid applying the insecticide when bees and other pollinators are present, as they can be harmed by the insecticide.
Advantages of Systemic Insecticide
Systemic insecticides have several advantages over contact insecticides. Here are some of the key benefits:
- Long-lasting effects: Systemic insecticides are absorbed by the plant and provide longer-lasting protection against pests. They can remain effective for weeks or even months after application.
- Effective against hidden pests: Systemic insecticides can reach pests that are hidden inside the plant, such as those that feed on the roots or inside the stem. Contact insecticides, on the other hand, only affect pests that come into direct contact with the spray.
- Reduced environmental impact: Because systemic insecticides are absorbed by the plant, they are less likely to be washed away by rain or irrigation. This means that less of the chemical ends up in the surrounding environment.
- Convenient application: Systemic insecticides can be applied to the soil or foliage of the plant, making them easy to use and reducing the risk of exposure to the applicator.
However, it is important to note that systemic insecticides can also have some drawbacks. They can be toxic to beneficial insects, such as bees and butterflies, and can accumulate in the soil over time. It is important to use systemic insecticides judiciously and only when necessary.
Advantages of Contact Insecticide
Contact insecticides have several advantages over systemic insecticides. Some of the advantages are:
- Contact insecticides act quickly and provide immediate results. They kill insects on contact with the plant surface.
- Contact insecticides are less expensive than systemic insecticides.
- They have a shorter residual effect, which means they don’t stay in the environment for long periods of time.
- They are less likely to cause harm to non-target organisms, such as beneficial insects and animals.
- Contact insecticides can be used in specific areas where pest infestations are localized, reducing the amount of chemical exposure to the environment.
However, contact insecticides also have some disadvantages. They only provide protection to the plant surface and do not penetrate the plant’s tissues. Therefore, they may not be effective against insects that feed on the plant’s internal tissues. Additionally, contact insecticides need to be applied more frequently than systemic insecticides to maintain their effectiveness.
Overall, contact insecticides are a useful tool in pest management programs, especially when used in combination with other pest control strategies.
Disadvantages of Systemic Insecticide
While systemic insecticides have several advantages, they also have some disadvantages that should be considered before using them. Here are some of the drawbacks of using systemic insecticides:
- Environmental Impact: Systemic insecticides can harm non-target organisms, including beneficial insects, birds, and mammals, as well as contaminate soil and water sources. They can also accumulate in the food chain, leading to long-term effects on ecosystems.
- Resistance: Overuse of systemic insecticides can lead to the development of insecticide resistance in pest populations, making them less effective over time. This can result in the need for higher doses or more frequent applications, which can further harm the environment and increase costs.
- Slow Action: Systemic insecticides may take longer to control pests than contact insecticides, as they rely on the pest to ingest the insecticide before it can take effect. This can be a disadvantage when immediate control is necessary.
- Cost: Systemic insecticides can be more expensive than contact insecticides, which can be a disadvantage for growers or homeowners on a budget.
It is important to weigh the advantages and disadvantages of systemic insecticides before using them. While they can be an effective tool for controlling pests, they should be used judiciously and with caution to minimize their impact on the environment and non-target organisms.
Disadvantages of Contact Insecticide
Contact insecticides are one of the most commonly used types of insecticides, but they have some downsides. Here are some of the disadvantages of contact insecticides:
- Short residual effect: Contact insecticides have a short residual effect, meaning they only remain effective for a short period of time. This means that they need to be reapplied frequently, which can be costly and time-consuming.
- Only effective on surface pests: Contact insecticides are only effective on pests that come into direct contact with the insecticide. This means that they are not effective against pests that are hidden or that feed on the plant’s internal tissues.
- Can harm beneficial insects: Contact insecticides can harm beneficial insects such as bees and ladybugs, which can have a negative impact on the ecosystem.
- Can build up resistance: Pests can build up resistance to contact insecticides over time, which can make them less effective.
Overall, while contact insecticides can be effective against some pests, they have some significant disadvantages that should be taken into account when deciding which type of insecticide to use.
Safety Concerns of Systemic Insecticide
Systemic insecticides are designed to be taken up by the plant and transported to all parts of the plant, including flowers, leaves, and stems. Because of this, there are some safety concerns that should be considered when using systemic insecticides.
One of the main concerns is the potential for the insecticide to be present in the plant tissue when it is consumed by humans or animals. While many systemic insecticides are considered safe for humans and animals when used according to label instructions, there is still a risk of exposure if the insecticide is not used properly.
Another concern is the potential for the insecticide to persist in the environment. Some systemic insecticides have been found to persist in soil and water for extended periods of time, which can lead to unintended exposure for non-target organisms, such as beneficial insects or wildlife.
It is important to follow all label instructions when using systemic insecticides, including wearing appropriate personal protective equipment, applying the insecticide at the recommended rate and timing, and avoiding application near water sources or areas with high wildlife activity. Additionally, it is important to properly dispose of any unused insecticide and follow all local regulations for disposal.
Safety Concerns of Contact Insecticide
Contact insecticides are known to have certain safety concerns that users should be aware of. While they are effective in killing pests on contact, they can also pose risks to humans and animals if not used properly. Here are some safety concerns to keep in mind when using contact insecticides:
- Direct exposure to the skin or eyes can cause irritation, redness, and itching. Always wear protective clothing and goggles when handling contact insecticides.
- Inhaling the fumes or dust from contact insecticides can cause respiratory problems, such as coughing, wheezing, and shortness of breath. Always use contact insecticides in well-ventilated areas and avoid breathing in the fumes or dust.
- Accidental ingestion of contact insecticides can cause nausea, vomiting, and diarrhea. Keep contact insecticides out of reach of children and pets, and always follow the instructions on the label.
- Contact insecticides can also harm beneficial insects, such as bees, butterflies, and ladybugs, which play important roles in pollination and pest control. Use contact insecticides sparingly and only when necessary to avoid harming beneficial insects.
It is important to read the label and follow the instructions carefully when using contact insecticides. Always wear protective clothing and goggles, use in well-ventilated areas, keep out of reach of children and pets, and avoid harming beneficial insects. By following these safety precautions, users can effectively control pests while minimizing risks to themselves and the environment.
Conclusion
Systemic and contact insecticides are two different types of pesticides that are used to control insect pests. Both types of insecticides have their own advantages and disadvantages, and they are used in different situations depending on the type of pest and the crop being grown.
Systemic insecticides are absorbed by the plant and are transported throughout the plant’s tissues, making the entire plant toxic to insects. This makes systemic insecticides very effective against herbivorous insects that feed on the plant’s tissues. However, systemic insecticides can be harmful to beneficial insects that feed on the plant’s tissues, and they can also be harmful to humans and other animals that consume the plant’s tissues.
Contact insecticides, on the other hand, are applied directly to the surface of the plant and are effective against insects that come into contact with the insecticide. Contact insecticides are generally less toxic to beneficial insects and other animals than systemic insecticides, but they may not be as effective against certain types of pests that feed on the plant’s tissues.
It is important to carefully consider the type of insecticide that is used in any given situation, taking into account the type of pest being controlled, the crop being grown, and the potential impact on beneficial insects and other animals. Integrated pest management (IPM) strategies that combine the use of multiple control methods, including biological control, cultural control, and chemical control, are often the most effective approach to managing insect pests in a sustainable and environmentally friendly manner.
Also Read: Thiocyclam Insecticide
Sources: Egwuatu, R. I. (1982). Field trials with systemic and contact insecticides for the control of Podagrica uniforma and P. sjostedti (Coleoptera, Chrysomelidae) on okra. International Journal of Pest Management, 28(2), 115-121. Link: https://www.tandfonline.com/doi/abs/10.1080/09670878209370687
Kubik, Marek, et al. “Pesticide residues in bee products collected from cherry trees protected during blooming period with contact and systemic fungicides.” Apidologie 30.6 (1999): 521-532. Link: https://www.apidologie.org/articles/apido/abs/1999/05/Apidologie_0044-8435_1999_30_6_ART0007/Apidologie_0044-8435_1999_30_6_ART0007.html
