Wednesday, December 19, 2012

A Slug's Life: Parasitism - Intro

It's time now to discuss a very disagreeable subject, but one which is nonetheless vital in understanding how a slug experiences the world. I first observed one of our slugs (Lehmannia valentiana) infected with a parasite a few months ago, and since then I've come across several more cases, including one in Deroceras laeve, which I will present to you in subsequent posts. For now I would simply like to introduce you to the topic of parasitism in slugs.

Without a laboratory and the proper equipment I cannot identify the species of parasite that has claimed the lives of several of our slugs, but I believe it is a kind of nematode (roundworm). According to the Nematology Department at the University of Nebraska-Lincoln, "nematodes are the most numerous multicellular animals on earth. A handful of soil will contain thousands of the microscopic worms, many of them parasites of insects, plants or animals." So unless I could actually take a sample from an infected slug, I have no way of knowing what this parasite is. However, I think the roundworm's small size and abundance makes it a likely culprit, and I can (and will) provide photos and descriptions of the manifestations of this presumed nematode, i.e. the characteristics of the exterior growths on the slugs' bodies.

Before I proceed, I would like to say that yes, I am aware that nematodes are used to curb slug populations in gardens. For instance, Nemaslug (produced by Nemasys) is a popular product. I've seen a photo of a slug being consumed by the commonly used nematode Phasmarhabditis hermaphrodita. The concentration of nematodes in such a "slug killer" is high, practically infesting the garden with them. Apparently this is considered the most effective way of controlling slugs. It may be effective, but is it humane? I beg to differ. From what I've seen, slugs are capable of experiencing suffering, admittedly not on a level with humans, but to some degree. Imagine yourself being consumed by microscopic worms or walking around with a huge tumor between your eyes! Of course I'm no advocate for "slug rights" on par with humans, but they are God's creatures, and we, as the stewards of God's earth, should treat them as such. Before you take any action against slugs, like sprinkling 300,000 nematodes per square meter of your garden, consider how much damage they're really doing to your plants and if there is another way to curb that. Some people kill slugs simply because they hate them and are disgusted by them. I was once disgusted by them too, but now that I understand more of their biology, I can appreciate the care with which God made them.

It's been emotionally difficult for me to observe so many infected slugs while being powerless to help them. If the time, effort, and money were worth the outcome, I would find an antidote for the nematode and inject my slugs with it. But God created nematodes too, however parasitic they are. Remember that whereas parasites attach themselves to a host from which they will feed, eventually killing it, we and other creatures kill our food right away. A parasite is nothing more than a live-in predator. It has to eat to survive, just as we do. I dislike parasites intensely; they make my skin crawl, and I detest their invasion of creatures that I love, such as slugs and dogs. But they, like other predators, control population growth. If animals were immune to everything and had no predators, the world would be bursting at the seams for want of space. Now, the killing of creatures by other creatures is the result of Sin's entrance into the world, but in its own way that element controls the excesses of reproduction. Without Sin, the population of all creatures would be stable and harmonious, not immune to death necessarily, but void of sickness or overabundance, so that every species would have room to flourish without imposing on another. Unfortunately, until the return of Christ, we must live in this Sin-filled world, and that means that we must witness the suffering of fellow creatures. I've had to come to terms with that, because I want so much to help my slugs, but a friend of mine helped me realize that even the silent suffering of a seemingly insignificant, often hated animal such as a slug, does not escape the notice of our Father in Heaven, who grieves for every one of His creatures that is sick or in pain.

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