Thursday, April 21, 2011

In Memory of Slugs

Yellow Garden Slug, Limax flavus
Why do slugs attack seedlings? For food, certainly, but why every year do gardeners and farmers have to spend millions on controlling their attacks on emerging crops? Take the Yellow Garden Slug, Limax flavus. This large yellowish slug with a mottled olive-brown body is found throughout Europe, as well as an introduction in America and Australia (1). Interestingly, it produces a lectin (LFA) that has been shown to disrupt neurotoxins produced by Clostridium botulinum and C. tetani (2). It feeds voraciously on seedlings and vegetables, often causing significant damage to root crops such as carrots and potatoes (3). Does L. flavus remember the specific food stuff that it likes, or does it use a trial and error feeding habit?
Yellow Garden Slug, Limax flavus
Well it seems that it has a very good memory indeed. L. flavus is attracted to smells and the range of it memory was demonstrated when the slug was conditioned to avoid carrots, a favoured food (4). This was achieved by presentation of carrot juice along with the bitter tasting quinidine sulfate. Retrograde amnesia of this event was achievable by cooling the slug, after which it continued to feed as normal. However a few days after conditioning, retrograde amnesia could not be induced by cooling. This showed that L. flavus has three memory states: short term, which is followed by long term-cooling sensitive, which is in turn followed by long term-cooling insensitive. Further investigation showed that reactivation of memory in L. flavus altered the memory state from cooling insensitive to cooling sensitive (5). These discoveries compare well with those found in other animals, showing that L. flavus remembers very much as we do.


  1. Sterry 2004, Collins Complete Guide to Irish Wildlife p. 156
  2. Bakry et al. 1991, Journal of Pharmacology and Experimental Therapeutics 258 pp. 830-836
  3. Davidson 1976, Oecologia 26 pp. 267-273
  4. Yamada et al. 1992, The Journal of Neuroscience 12 pp. 729-735
  5. Sekiguchi et al. 1997, Learning and Memory 4 pp. 356-364


  1. This shows that there is more to slugs than most people realise.

  2. "It feeds voraciously on seedlings and vegetables, often causing significant damage to root crops such as carrots and potatoes (3)" .. This sentence ascribed to Davidson is not a direct quote.. only his reference to assimilation of carrot and potato material. Davidson does not say they feed voraciously on seedlings and vegetables.