Before delving into the main types of insecticides, it is important to consider the various properties of insecticides, which can impact their utility and effectiveness of the product.
Toxicity
The toxicity of an insecticide refers to its ability to act as a poison. To manage specific pests, rigorous testing is conducted on new insecticides to assess their toxic effects on these pests.
Hazard
This refers to the risk associated with handling and using pesticides. The hazard level can vary, A highly toxic pesticide may be used in a low-risk manner, while a less toxic pesticide could pose a higher risk if used inappropriately. Several factors such as the pesticide chosen, the type and condition of equipment, and weather conditions, can affect the overall hazard level in a pest control operation.
Spectrum of activity
This refers to the variety of pests the insecticide can effectively target. Insecticides with the capability to eliminate a wide range of insects, such as pyrethrins, are described as having a broad spectrum of activity. On the other hand, insecticides that are effective against only specific types of insects are characterised as having a narrow spectrum of activity.
Mammalian toxicity
The assessment of the toxicity of an insecticide to mammals is typically conducted through testing with experimental animals, often rats. The comparative indicators of mammalian toxicity for an insecticide are commonly presented as: Oral LD50 (mg/kg; that is, in milligrams of poison per kilogram ofbody weight); Derman LD50 (mg/kg); and Inhalation LC50 (usually in mg/m3 for 4 hours)
Persistence
Most insecticides experience a decline in effectiveness after application. When this decline is gradual, the insecticides are termed persistent or stable. Dieldrin, for example, remains active in solid for over 40 years, making it a stable and persistent insecticide. In contrast, some insecticides have a short residual life, like dichlorvos, which may break down rapidly, often within hours of application. The stability of insecticides varies chemically, ranging from hours to many years. Environmental factors and the characteristics of the applied surface, including sunlight, moisture, and heat, can also impact their residual life and stability.
Volatility
The volatility of an insecticide indicates how easily it transitions from a liquid to a gaseous state. Insecticides with high volatility, such as dichlorvos, have the potential to function as inhalation poisons.
Repellency
An insecticide’s repellency is its ability to keep insects away from a treated area. Pyrethrins, known for their repellent action, are sometimes used in low concentrations as a space spray to repel flying insects.
Flushing action
An insecticide’s flashing action agitates insects in treated areas, causing them to leave their hiding spots. Pyrethrins are known for this effect. Flushing agents, when permitted by label directions, may be added to surface sprays to improve contact with treated surface. Alternatively, they can be used independently to uncover hidden insect activity. Operators often use a small aerosol or pyrethrins in cracks and crevices to reveal information about a cockroach infestation.
Knockdown action
This refers to the rapid intoxication and partial paralysis of an insect by a fast-acting insecticide. Pyrethrins, and some synthetic pyrethroids, known as knockdown agents are commonly included in products for this purpose.
Compatibility
Chemical compatibility pertains to the ability of two chemicals to be combined without adverse effects. When it comes to pesticides, it is crucial to mix them only if the label instructions confirm the compatibility of one product with another.
Phytotoxicity
The phototoxicity of an insect signifies its level of toxicity to plant life. Insecticides labelled as phytotoxic should not be used on plants.
Withholding period
This is the duration that needs to pass between applying a pesticide