What is the Difference Between Systemic and Contact Insecticide

The main difference between systemic and contact insecticide is that systemic insecticide kills pests that feed on plants whereas contact insecticide kills pests when they come into contact with the insecticide.

Systemic and contact insecticides are two types of insecticides that destroy, suppress, or inhibit insects. Generally, they differ in the mode of action.

Key Areas Covered

1. What are Systemic Insecticides
– Definition, Structure, Function
2. What are Contact Insecticides
– Definition, Structure, Function
3. Similarities Between Systemic and Contact Insecticide
– Outline of Common Features
4. Difference Between Systemic and Contact Insecticide
– Comparison of Key Differences

Key Terms

Contact Insecticide, Systemic Insecticide

What is Systemic Insecticide

Systemic insecticides are insecticides that are absorbed and transported throughout the plant. Therefore, some parts or the entire plant become toxic to insects. Therefore, this type of insecticide is important to suppress insects that feed on plant tissue. Systemic insecticides can be used against sucking or chewing insects like aphids, caterpillars, and root nematodes. However, one drawback of systemic insecticide is that it kills both harmful insects and beneficial insects.

Figure 1: Systemic Insecticides

Furthermore, plants absorb systemic insecticides and transport them throughout the plant. Insects ingest systemic insecticides along with the plant parts that they feed on. Transgenic plants produce systemic insecticides. Therefore, this type of plant contains plant-incorporated protectants. Moreover, these plants produce proteins that kill insects.

What is Contact Insecticide

Contact insecticides are the type of insecticides that kills insects when they come into direct contact with the plant. They penetrate the skin of the insect and kill it. These insecticides are important for killing insects such as aphids that pierce the plant surface in order to suck the juice. There are two types of contact insecticides: naturally occurring compounds and synthetic inorganic, organic ones. Some of the naturally occurring contact insecticides include nicotine, pyrethrum, and rotenone obtained from flowers of Chrysanthemum cinerariaefolium and Tanacetum coccineum,  and oils, from petroleum.  

Figure 2: Aphids

Meanwhile, inorganic insecticides include sulfur, arsenate, copper, and fluorine compounds. In addition, organic chemical compounds can work as synthetic insecticides.

Similarities Between Systemic and Contact Insecticide

• Systemic and contact insecticides are two types of insecticides that kill insects.
• Both differ in their mode of action.

Difference Between Systemic and Contact Insecticide

Definition

Systemic insecticide refers to insecticides that are absorbed and transported through plants while contact insecticide refers to insecticides that kill on contact, rather than after ingestion or absorption.

Significance

Usually, systemic insecticide kills pests that feed on the plant while contact insecticide kills pests when they come into contact with the insecticide.

Function

Importantly, systemic insecticide makes all of a plant toxic to insects; therefore, it kills the insects that feed on plant tissue such as herbivorous sucking or chewing insects like aphids, caterpillars, and root nematodes, while contact insecticides help to remove insects that pierce the surface of the plants; they penetrate the skin of the pest to kill them.  

Conclusion

In brief, systemic and contact insecticides are two types of insecticides that kill insects on plants. Systemic insecticides kill the insects that feed on the plant. Therefore, these types of insecticides are absorbed and transported throughout the plant. Generally, systemic insecticides are useful for insects that feed on plants such as aphids, caterpillars, and root nematodes. In contrast, contact insecticides remain outside the plant and they penetrate the skin of the insects. Usually, contact insecticides are important for insects that come into contact with the plants such as aphids. Hence, the main difference between systemic and contact insecticides is their mode of action.

References:

1. “Insecticide.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
2. “Systemic Insecticides: A Reference and Overview.” The Xerces Society for Invertebrate Conservation.

Image Courtesy:

1. “Tractor Fertilize Field Pesticide And Insecticide” By Aqua Mechanical – Own work (CC BY 2.0) via Commons Wikimedia
2. “Treehopper, adults, nymph & eggs, Calloconophora sp.” By Andreas Kay – Own Work (CC BY-NC-SA 2.0) via flickr