VARIATIONS IN WEB CONSTRUCTION IN LEUCAUGE VENUSTA (ARANEAE, TETRAGNATHIDAE)

Abstract

The distribution of female Leucauge venusta (Walckenaer 1841) in a coffee plantation in southern Mexico was studied in order to determine the vertical distribution of this spider. Principal component analysis clearly identified the presence of three distinct groups of L. venusta webs, based on the number of spirals/web and principally on the height at which the webs were located; most L. venusta webs (63/100) were close to the ground. Spiders on high webs (153.8 ± 3.6 cm above ground, mean ± S.E.) were significantly larger and heavier than spiders on lower webs. Large spiders had significantly larger, better developed ovaries, than smaller conspecifics, presumably indicative of sexual maturity. Significantly more insects were captured by sticky traps placed at 50 cm height than in the traps placed at 150 cm height; the most numerous captures were Diptera. However, insects caught at 150 cm were significantly larger than those caught at 50 cm above ground. We concluded that as sexual development proceeds, the spider increases the height at which the web is constructed. This vertical migration is associated with changes in web construction and the type of prey captured. These results are discussed in terms of intraspecific competition, predation risks and sexual selection.