A study of disturbance behaviors in Uloborus glomosus (Araneae; Uloboridae) as possible predator avoidance strategies

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Virginia Tech


When touched with a contact stimulus, 50% of adult Uloborus glomosus jumped from the web; 33% remained motionless; 13% moved to the edge of the web; and 4% shook the web. In a population of juveniles, 45% moved to the edge of the web; 27% jumped from the web; 24% shook the web; and 4% remained motionless.

Adults with either stabilimenta or eggsac chains in their webs showed a tendency to shake their webs in the morning and move to the edge in the evening. Those without web structures jumped from their webs throughout the day. Juveniles with stabilimenta shook their webs in the afternoon; those without stabilimenta shook their webs in the evening. Adults aligned with web structures remained motionless when disturbed.

Marked adults observed over the course of 4 weeks moved to the edge of the web or remained motionless when contacted in the mornings and jumped in the afternoons and evenings. During this time, the frequency of the jumping behavior increased.

An adult U. glomosus jumped from its web in response to contact by a spider-hunting wasp. Other spiders tested with a contact stimulus and the combined visual and vibratory stimuli produced by a tethered wasp responded only to contact.

Females tending their eggsac chains exhibited two types of defensive behaviors when either the parasitoid Arachnopteromalus dasys or spiderlings were placed on their eggsacs. They jerked their webs and swept the eggsacs with their long front legs.