I Frequently Read About How Gardeners Can Make A Homemade Slug Killer “Soup”, But There Are Many Reasons Why It Usually Fails To Kill Slugs.

The theory is that you make your own mix by drowning slugs and spraying the concoction on plants. The idea is that the slugs would either be repelled by the scent of the deceased slugs or killed by the nematodes. The reasons are often vague and confused! For me, and many others, Homemade Slug Nematodes simply usually don’t work – a classic example of pseudoscience!

Homemade Slug Nematodes Often Won't Kill Slugs

The article talks about nematodes that live inside slugs for part of their life cycle, killing the host, feeding, breeding, and then seeking new slug victims. One such species, Phasmarhabdatis hermaphrodita, is sold as a biocontrol under the trade name Nemaslug. These nematodes are safe for other animals, birds, worms, and plants, and even occur naturally in our soil in small numbers.

(Studies by Rae et al (2005) using the same nematode showed no effect on five earthworm species commonly used in composting. However Edmond Zaborski has found A Possible Phasmarhabditis sp. (Nematoda: Rhabditidae) Isolated from Lumbricus terrestris (Oligochaeta: Lumbricidae). It has been identified as using the earthworm as a phoretic host. That means it causes no harm to the host but uses it to travel on. Like using it as a taxi! )

As usual, things are more complex than simply sprinkling nematodes on the soil. These nematodes alone won’t kill slugs.Researchers found they need to be at a specific life cycle stage (dauer larvae) and infected with a particular bacteria (Moraxella osloensis). Neither of these partners is naturally abundant enough in our gardens to significantly impact slug populations.

So why aren’t the nematodes effective alone? The bacteria need to be inside the nematode, which in turn needs to be at the right stage and inside a slug. Then, the worms release the bacteria, which multiplies and releases a toxin that kills the slug.This toxin is particularly effective against the grey field slug, but results with other species, larger slugs, adult slugs, and snails are more variable.

Nemaslug Is Just Part Of The Solution

Mass producing nematodes requires specialised equipment, sterile conditions, and careful aftercare. They’re grown in giant vats with a specific food and nutrient matrix, then inoculated with the symbiotic bacteria. Both organisms need ideal temperatures and conditions throughout the process. The nematodes themselves are “nursed” through two or three generations before reaching the infected juvenile form lethal to slugs. Someone has to monitor their life cycle, and if conditions aren’t ideal, their numbers suffer.

Once at the right stage, the nematodes are harvested, mixed with an inert carrier, and partially dehydrated to conserve energy. They need to be kept cool (around 40°F), protected from freezing and sunlight, and packaged in special bags allowing air exchange but retaining moisture. Under refrigeration, they can survive up to 6 months. The homemade “soup” wouldn’t come close to meeting these requirements.

Nemaslug, patented in 1993 by Becker Underwood, is simple to use. Open the bag, add to clean water, stir, and apply to the soil surface with a watering can. Effectiveness depends on following the instructions: using clean water, applying during suitable conditions (soil temperature and moisture), and watering directly to the soil, not foliage. A typical package contains enough nematodes (around 12 million!) to treat a designated area, giving them a better chance to find a slug.Temperature, soil type, and moisture retention all affect the nematodes’ survival and dispersal. Failure to follow instructions can render them ineffective.

These products are made by experts in high-quality labs with state-of-the-art equipment. The commercial product is the result of teamwork between bacteriologists, nematologists, entomologists, malacologists, biochemists, molecular biologists, and industry experts, all working together to understand and exploit the unique attributes of symbiosis.

While the infected nematodes kill many slugs and snails, they’re not a universal solution. The grey field slug is certainly susceptible, but the larger leopard slug, for example, can trap invading nematodes by increasing its shell size. (Though not visible, slugs are actually snails with a hidden “shell” made of a thin calcium carbonate membrane.) So I recommend using nematodes in combination with Slug Pubs.

The nematode life cycle requires them to feed and reproduce within the infected slug. During this stage, both the slug and the nematodes are vulnerable to predation by ground beetles like Pterostichus melanarius. However, researchers found that slugs infected with nematodes actually deter the beetles from consuming them, even though the nematodes can’t infect insects. The nematode-bacteria combination essentially protects both itself and the slug from being eaten.

Homemade Slug Nematodes Conclusion

Image Attribution: slug.-Msmurugan1-CC-BY-SA-4.0-https-creativecommons.orglicensesby-sa4.0-via-Wikimedia-Commons
Tag: Homemade Slug Nematodes

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