WEB ORIENTATION, STABILIMENTUM STRUCTURE AND PREDATORY BEHAVIOR OF ARGIOPE FLORIDA CHAMBERLIN & IVIE 1944 (ARANEAE, ARANEIDAE, ARGIOPINAE)

Abstract

This study was undertaken to describe the web orientation, stabilimentum structure and predatory behavior of Argiope florida Chamberlin & Ivie 1944 (Araneae, Araneidae, Argiopinae), a vir- tually unstudied orb-web spider of the southeastern United States. Adult female Argiope florida were sampled from five sandy ridge areas of Florida. Compass orientation of the spider's dorsum, incline of the web from vertical and hub height were measured. The presence of male A. florida, barrier webs, kleptoparasitic species of Argyrodes Simon 1864 (Araneae, Theridiidae), wrapped prey and large areas of web damage were noted. Predatory behavior was elicited by touching a radius with a 100 Hz tuning fork. The number of stabilimentum arms was measured, along with their arrangement, length and number of silk bands. On average, webs faced 100 8 E of N, were inclined 198 from vertical and were 1 m from the ground at the hub. Responses to the tuning fork, which closely resembled the responses to actual prey, were more vigorous when Argyrodes spp. were present on the web, but were not different when wrapped prey were present on the web. Most webs had stabilimenta and most stabilimenta had four arms in a cruciate pattern. The upper arms tended to be smaller and spaced further apart than the lower arms. Spider size was related to the angle between the lower arms of the stabilimentum, but not to other measures of the stabilimentum.