Azadirachtin: How It Works, Target Pests & Precautions
Azadirachtin is a compound that is extracted alongside other compounds from the seed kernels, leaves, and barks of the neem tree. The extract is used as an organic insecticide and fungicide owing to its natural ability to kill, harm, and repel some species of insects through various modes of action including feeding inhibition, growth regulation, and sterilization among others. Products containing Azadirachtin are largely considered non-toxic to mammals though potentially toxic to some beneficial insects including bees, ladybugs, and aquatic organisms.
Where Does Azadirachtin Come From?
Harvested from the neem tree (Azadirachtin indica), a member of the mahogany family, azadirachtin comes from different parts of the world key among them being India, Africa, and Iran. Although it is available in the barks and leaves of the plant, the seed kernel is its richest source with seeds from Ghana having as much as 3.5g/kg of the compound compared to Indian seeds which range between 0.2 g/kg to 0.75 g/kg.
Therefore, although native to India, Azadirachtin is found in all regions of the world that support neem tree growth. It is worth noting that the neem tree thrives in subtropical and tropical conditions specifically in areas with deep permeable soils.
In the US, the compound is registered as a technical powder as well as an end-use product for indoor and outdoor use.
How It Works
This organic insecticide possesses multiple modes of action against pathogens. As such, it is a highly versatile compound that is not only useful for crop management but also in the management of fleas and ticks in household pets like dogs and cats. Some of its modes of action include:
*Antifeedancy
The substance works by preventing insect feeding or suppressing (slowing down) further feeding. It particularly achieves this by hindering the abilities of herbivorous insects to feed thereby preventing them from attacking the leaves in the first place.
*Growth Regulation
This natural insecticide acts as an insect growth disruptor by inhibiting the production of the ecdysone hormone which is responsible for molting. As a result, this causes the insects to die when transitioning from one stage of life to another thereby preventing the emergence of future generations.
*Fecundity Suppression & Sterilization
This mode of action involves weakening female fertility and causing male sterilization. By impeding their ability to mate and multiply, Azadirachtin effectively helps reduce insect populations over time thereby leading to substantial reductions in harmful insect populations.
*Oviposition Repellency
One way to manage insect pests is by reducing their ability to lay eggs. Azadirachtin achieves this by altering the physical and chemical properties of the insects’ immediate environment thereby interfering with their usual behaviors. This helps reduce the number of eggs laid per insect thereby helping impede their population growth over time.
*Changes in Biological Fitness
Insect populations tend to develop certain adaptational responses to their immediate environment; something that enables them to grow and thrive. With its ability to cause changes in the developmental and reproductive activities of the insects, azadirachtin triggers changes in insect biological fitness which, in turn, interferes with their growth and survival abilities.
*Blockage of Development
This organic insecticide can hinder the development of insect larvae. It accomplishes this by disrupting the normal hormonal processes in the insects it is targeted at triggering development impediments. Also, by preventing molting, it prevents larvae from progressing to the next stage of development.
Common Pests It Is Effective Against
This biopesticide is mostly effective against insects that feed on plant leaves, flowers, and fruits. Some of those include:
Aphids – Aphids feed on plant sap leaving significant damage behind. As a feeding deterrent, azadirachtin causes aphids to reduce or completely stop eating, leading to their eventual death. Besides that, it acts as an aphid repellent causing the soft-bodied pests to avoid the treated plants.
Whiteflies – Azadirachtin helps in the management of plant-attacking insects by inhibiting their natural ability to reproduce and feed. When whiteflies come into contact with the pesticide, it interferes with their normal growth eventually causing them to die.
Thrips – Besides interfering with their development cycle, azadirachtin also acts as an antifeedant and oviposition repellent to thrips consequently reducing their rate of reproduction. The organic extract’s repellent effect also causes the thrips to stay away from treated plants.
Caterpillars – This plant-derived insecticide acts as a “stomach poison” meaning caterpillars usually end up ingesting it during feeding something that makes it highly effective against caterpillars. Besides that, it hinders molting effectively preventing caterpillars from advancing into moth or butterflies – as a result helping in controlling their populations.
Azadirachtin Safety & Precautions
Although generally considered safe for agricultural and gardening applications, Azadirachtin should always be used as directed to avoid potential health risks. Some precautions worth taking include:
- Wearing protective clothing when using it.
- Storing it safely in a cool dry place away from open flames.
- Avoiding its use during the blooming period to protect bees.
- Applying azadirachtin early in the morning or late in the evening when beneficial insects like bees and ladybugs are less active.
- Avoiding applications directly into water bodies to prevent the pesticide from killing aquatic organisms.
- Using appropriate equipment and techniques to reduce excessive runoffs that could affect beneficial insects or aquatic organisms.
Application
Azadirachtin can be applied through seed treatment, soil drenches, or foliar sprays depending on the target pest. Clinical experiences (1, 2) suggest that the neem extract should be sprayed every few days. Worth noting is that the extract has a residual life of 7 days in the field and although its effects may last longer under the soil due to reduced exposure to sunlight hence regular applications may help sustain its effectiveness over time.
Conclusion
In conclusion, Azadirachtin is an organic compound that is commonly sourced from the seed kernels of neem trees. The biopesticide is largely safe for humans when applied to plants as directed although potentially toxic to aquatic organisms and some beneficial insects. Therefore, it should be used with caution to ensure it achieves its intended effects as an organic pesticide and fungicide.
