Are you considering using neem oil as a natural insecticide in your garden, but worried about the potential harm it may cause to earthworms?
You’re not alone. Many gardeners are concerned about the impact of neem oil on these beneficial creatures. However, the good news is that neem oil is generally safe for earthworms, and may even have some positive effects on their activity and reproduction.
In this article, we’ll explore the research on neem oil and earthworms to help you make an informed decision about using this natural pest control method in your garden.
So, let’s dive in and find out if neem oil will hurt worms!
Will Neem Oil Hurt Worms?
Neem oil is a natural insecticide that has been used for centuries to repel, harm, or kill over 200 different kinds of pests. However, many gardeners are concerned about the impact of neem oil on earthworms, which are beneficial creatures that play a vital role in maintaining healthy soil.
The good news is that neem oil is generally safe for earthworms, and may even have some positive effects on their activity and reproduction. According to research, neem products are used to improve soils in India and other countries where neem grows. The neem product used as soil conditioner is called Neem cake, which is the solid residue that is left after neem seed kernels have been crushed to extract neem oil.
All parts of the neem tree contain the active ingredients, though in varying concentrations. That means, even if neem cake has been thoroughly de-oiled, it still contains all the active substances in the dry matter that’s left. And that dry matter improves soils, increases the number of beneficial organisms and helps protect plants from soil born pests and diseases.
Farmers know from experience that neem cake stimulates earthworm activity. Earthworms do great in soils treated with neem cake. Researchers have also done some studies to get hard numbers and facts regarding neem and earthworms. Either neem leaves or neem seed kernels were ground and then added to the potting soil in a greenhouse. The number of earthworms in the soil increased by 25%. In a similar field trial various neem products were added to the soil. The worms did not move into the soil as fast as they moved into untreated soil. But once the worms entered the soil they grew a lot better. The number of earthworms was the same as in untreated soil, but the weight of the worms in the neem treated soil was higher.
Researchers even vermicomposted neem itself. The worms loved the neem, fed on it voraciously, and as a result grew a lot faster and multiplied more than if fed with mango leaves.
While traditional chemical pesticides can harm earthworms, neem oil has the opposite effect by encouraging earthworm activity. Earthworms are beneficial to garden soil as they tunnel through the dirt, creating pathways that allow air and rainwater to reach plant roots. These little guys also leave behind excrement, known as casts, that contain nutrients for the soil, including potassium, nitrogen and phosphorous. When earthworms die, their decaying bodies also help fertilize the soil.
What Is Neem Oil And How Does It Work As An Insecticide?
Neem oil is a natural insecticide that is derived from the seeds of the neem tree. It contains many components, with azadirachtin being the most active. Azadirachtin reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed.
When neem oil is applied to plants, it affects insects during all phases of their development, including when they are eggs, larvae (grubs), pupas, and adults. This makes it effective at controlling over 200 different kinds of pests, including whitefly, aphids, Japanese beetles, moth larvae, scale, and spider mites. Neem oil is also listed as a miticide because it kills mites, which are not insects but are related to spiders and ticks. Additionally, sprays containing clarified hydrophobic neem oil extract are used as fungicides against rust, black spot, mildew, leaf spot, scab, anthracnose, blight, and botrytis.
Neem oil works by interfering with the normal life cycle of insects. This includes feeding, molting, mating, and egg-laying. Neem oil does not harm birds or beneficial insects and soil-loving creatures such as bees, butterflies, lady beetles, and earthworms. In fact, neem oil can be used to encourage earthworm activity in garden soil.
To use neem oil as an insecticide, it should be sprayed on foliage in the morning or evening when beneficial bugs are dormant and not feeding or pollinating. It should be avoided in the middle of the day when the sun and heat could burn the sprayed foliage. Neem oil is effective at any time during a season because it affects insects during all phases of their development. It is safe for the environment and has a residual effect of helping earthworms.
The Importance Of Earthworms In The Garden Ecosystem
Earthworms play a crucial role in maintaining healthy garden soil. As they consume organic matter, they help to aerate the soil and improve its structure. This, in turn, can improve drainage and air circulation, making it easier for plant roots to penetrate the soil. Earthworms also bring value to the soil by taking nutrients from deep inside the soil and bringing them to the surface.
In addition to improving soil structure, earthworms also contribute to soil fertility. As they consume organic matter, they excrete casts that contain nutrients such as nitrogen, phosphorus, and potassium. These nutrients are then available for plants to use, which can lead to stronger and healthier growth.
Earthworms also help to break down organic matter in the soil, which can help prevent the buildup of harmful toxins and chemicals. This is particularly important if you’re using synthetic fertilizers or pesticides in your garden.
Research On The Effects Of Neem Oil On Earthworms
There aren’t many studies examining the effects of neem oil on earthworm growth, activity, and reproduction. However, the available research suggests that neem oil is generally safe for earthworms, as long as it’s applied in normal, recommended amounts. In fact, neem oil may even have positive effects on earthworm activity and reproduction.
In greenhouse studies, when neem leaves and seed kernels were incorporated into potting soil containing earthworms (Eiseniafoetida), the number of young worms produced increased by 25%. In a similar field trial, various neem products were added to the soil. The worms did not move into the soil as fast as they moved into untreated soil. But once the worms entered the soil, they grew a lot better. The number of earthworms was the same as in untreated soil, but the weight of the worms in the neem treated soil was higher.
Researchers even vermicomposted neem itself. The worms loved the neem, fed on it voraciously, and as a result grew a lot faster and multiplied more than if fed with mango leaves.
However, it’s important to note that neem oil can harm or kill earthworms if applied in excessively high doses. The LC50 of commercial neem extract on filter paper in the earthworm Pheretima peguana at 48 h and 72 h was 3.79 and 3.33 g, respectively. In earthworms exposed to five NEEM concentrations from 0.39 to 3.13 g, the radial thickness of the epidermis and body wall significantly decreased, and thickness of intestinal epithelium increased but only at high doses, approximately 25-fold above the concentration permitted for use as an insecticide in field applications (0.09 g). NEEM significantly increased the number of binucleated coelomocytes in the micronucleus test (detects chromosomal aberrations) at 3.13 g, approximately 35-fold higher than the recommended dose, but it did not cause coelomocyte DNA single-strand breaks in the comet assay.
Benefits Of Neem Oil For Earthworms
Neem oil is generally safe for earthworms, and may even have some positive effects on their activity and reproduction. Farmers and researchers have reported that neem cake, a byproduct of neem oil extraction, stimulates earthworm activity and improves soil quality. In fact, the number of earthworms in the soil increased by 25% when neem leaves or neem seed kernels were ground and added to the potting soil in a greenhouse. Additionally, various neem products were added to the soil in a field trial, which resulted in a higher weight of the worms in the neem treated soil. Researchers also vermicomposted neem itself and found that the worms fed on it voraciously, resulting in faster growth and multiplication compared to feeding them with mango leaves.
Earthworms are beneficial to garden soil as they create pathways for air and rainwater to reach plant roots. They also leave behind excrement, known as casts, that contain nutrients for the soil, including potassium, nitrogen, and phosphorous. When earthworms die, their decaying bodies help fertilize the soil. Traditional chemical pesticides can harm earthworms, but neem oil has the opposite effect by encouraging earthworm activity. Therefore, using neem oil in your garden can improve soil quality and promote a healthy ecosystem for earthworms and other beneficial organisms.
How To Safely Use Neem Oil In Your Garden To Protect Earthworms
If you plan on using neem oil in your garden, it’s important to take precautions to ensure that earthworms are not harmed. Here are some tips to safely use neem oil in your garden:
1. Use Recommended Amounts: Neem oil won’t harm or kill earthworms unless it’s applied in excessively high doses. If applied in normal, recommended amounts, neem oil has been shown to have positive effects on earthworm activity and reproduction, including a potential increase in the number of worms and their average weight.
2. Apply Neem Oil in the Evening: It’s important to apply neem oil in the evening when the sun is not as strong. This will give the oil time to dry before the sun comes up, which can cause burning on the leaves of plants.
3. Avoid Direct Spraying: When applying neem oil, be careful not to spray it directly on earthworms or their burrows. While neem oil won’t harm earthworms in small doses, direct spraying can still be harmful to them.
4. Use Soil Soak Method: Another way to use neem oil without harming earthworms is to soak the soil around your plants with a neem oil mixture. Pour 2 to 3 cups of the neem oil mixture around the base of each plant in your garden every 2 to 3 weeks until the insects have left the area or disease symptoms lessen. This will take at least 2 weeks for the effectiveness of neem oil to work on the garden soil.
By following these tips, you can safely use neem oil in your garden without harming earthworms. Remember, earthworms are beneficial creatures that play an important role in maintaining healthy soil, so it’s important to take care when using any type of pesticide or insecticide in your garden.
