Variation in the chemical composition of ore webs built by the spider Nephila clavipes (Araneae, Tetragnathidae)

The adhesive droplets in the orb webs of araneoid spiders contain, among ot her constituents, an aqueous solution of organic low-molecular-weight compo unds. The chemical composition of this solution has been investigated for p ooled web collections from several species, but little is known about how t he composition might vary among individuals or among environments. To begin addressing these questions, we analyzed serial collections of orb webs spu n by individual juvenile Nephila clavipes from three different populations held first under field conditions and then under laboratory conditions. Our results indicate that the composition of the organic low-molecular-weig ht solution is not fixed. We found significant differences in the droplet c omposition among individuals, among populations, and with the transfer of s piders to laboratory conditions. The possible origins and consequences of t hese differences are discussed.