Environmental and genetic background of tiptoe-initiating behaviour in the dwarfspider Erigone atra

Ballooning is a widespread behavioural trait in invertebrates, which enhances passive aerial dispersal. We investigated the influence of common lineage (family effect) and postnatal environmental conditions on latency to initiate preballooning tiptoe behaviour (ballooning latency) in the dwarfspider Erigone atra (Blackwall, 1841). The ballooning latency of individual spiders was tested in a specially designed test chamber. In a 3-week experiment, in which the spiders were fed only during the first day of each week, ballooning latency had low repeatability at weekly intervals. Ballooning latency declined with increasing food deprivation during the first week but not during the second and the third weeks. At intervals of less than I h, however, ballooning latency showed high repeatability. We also investigated whether maternal and postnatal environmental conditions (i.e. during juvenile development) influence phenotypic variation in ballooning latency. We reared offspring of several families under two feeding and two temperature conditions. Environmental conditions explained more variation in ballooning latency than family. Ballooning latency was lower in spiders reared at 20degreesC than in those reared at 15degreesC. In addition, spiderlings fed four prey per 3 days were faster ballooners than those fed only four prey per week. An interaction between factors was present, indicating the existence of different reaction norms between the two environmental conditions. The expression of ballooning latency behaviour thus strongly depends on current nutrition, feeding history and the feeding and temperature conditions during juvenile development. (C) 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.