ASSESSMENTS AND DECISIONS IN METELLINA-SEGMENTATA (ARANEAE, METIDAE) - EVIDENCE OF A PHEROMONE INVOLVED IN MATE GUARDING

Assessments and decision-making underlying the initiation of mate guar ding in a common web-building spider, Metellina segmentata, are examin ed in a series of field and laboratory studies. Adult males do not bui ld webs but wander in search of females and mating opportunities. Adul t males then wait at the edge of the webs of females and guard them pr ior to courtship and mating. Guarded females were heavier, larger and carried more mature eggs than solitary females. An active process of i nformation gathering is apparent from introductions of males to the we bs of females. Males make accurate assessments about female quality, e ven in the absence of the resident female. Cues involving web architec ture are not used. Males may assess pheromonal cues on the web of the female in deciding whether to guard or abandon a female.