ONSET AND MAINTENANCE OF MATERNAL PREY-SUPPLY ACTIVITY IN THE SPIDER COELOTES-TERRESTRIS (ARANEAE, AGELENIDAE)

In the funnel-web spider Coelotes terrestris (Agelenidae) the young are provided with prey by their mother for several weeks following emergence from the egg sac. Such a maternal activity has previously been shown to be influenced by stimuli emitted by the young (i.e. during mother-offspring interactions), which ensures the tuning of the prey supply to the maintenance of prey-supply tendency. The experimental procedure consisted in confronting females, either sub-adult or at various stages of their reproductive life cycle, with a group of spiderlings constant in number and age, and in recording the behavioural interactions following the capture of a prey item. Females which did not yet have post-emergence offspring did not supply prey to the spiderlings and exhibited aggressive reactions towards them. In contrast, females which had had post-emergence offspring, even though their dispersal could have taken place many weeks before, provided prey to the experimental spiderlings, and behaved towards them as their real mothers would have done. When exposure to the experimental situation was prolonged for one week, the tendency to supply the young clearly appeared in previously unresponsive adult females (inseminated or incubating), but no change was observed in sub-adults. The results show that, in Coelotes terrestris, the maternal tendency to supply prey requires a particular internal state, which seems to develop at the time of the offspring's emergence but which does not become extinct after their dispersal. The results also suggest that the development of this internal state can somehow be influenced by stimuli from the young.