Effect of psychoactive drugs on Spiders

In 1948, German pharmocologist P. N. Witt started his research on the effect of drugs on spiders. The initial motivation for the study was a request from his colleague, zoologist H. M. Peters, to shift the time when garden spiders build their webs from 2am-5am, which apparently annoyed Peters, to earlier hours.

Effect of psychoactive drugs on spiders

Witt tested spiders with a range of psychoactive drugs, including amphetamine (alpha-methylphenethylamine), mescaline (3,4,5-trimethoxyphenethylamine), strychnine (C21H22N2O2), LSD (Lysergic acid diethylamide) and caffeine, and found that the drugs affect the size and shape of the web rather than the time when it is built. At small doses of caffeine (10 µg/spider), the webs were smaller; the radii were uneven, but the regularity of the circles was unaffected. At higher doses (100 µg/spider), the shape changed more, and the web design became irregular. All the drugs tested reduced web regularity except for small doses (0.1-0.3 µg) of LSD , which resulted in more ordered webs.

The drugs were administered by dissolving them in sugar water, and a drop of solution was touched to the spider’s mouth. In some later studies, spiders were fed with drugged flies. For qualitative studies, a well-defined volume of solution was administered through a fine syringe. The webs were photographed for the same spider before and after drugging.

Effect of Drugs on Spiders

Witt’s research was discontinued, but it became reinvigorated in 1984 after a paper by Nathanson in the journal Science, which is discussed below. In 1995, a NASA research group repeated Witt’s experiments on the effect of caffeine, benzedrine, marijuana and chloral hydrate on European garden spiders. NASA’s results were qualitatively similar to those of Witt, but the novelty was that the pattern of the spider web was quantitatively analyzed with modern statistical tools, and proposed as a sensitive method of drug detection.

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