Effects of information asymmetries in contests between net spinning caddis larvae (Plectrocnemia conspersa)

During five days prior to the introduction of potential intruder larvae, residents were treated in four different ways. In one treatment the residents were unfed and their nets were taken away at daily intervals. Nets were not taken away in the other treatments, and residents were unfed, fed 2 or 4 items per day, respectively. Small intruders were equally successful as large ones in taking over low energy demanding nets of unfed, disturbed residents whose nets were taken away daily. Take overs of high ranked nets of larvae fed four prey items per day were mainly performed by large intruders. Low investment nets of unfed, disturbed resident larvae were often taken over during the first day upon the implantation of intruder larvae. On the contrary, unfed undisturbed larvae defending a five times as energy demanding net only suffered a slight net loss. Nets of unfed, undisturbed larvae were taken over somewhat more often than those from residents fed two prey per day. The results indicate prior treatment to inform these three resident categories of their resource values. Owners of high ranked nets fed two prey per day were most keen on defence during the first day upon introduction of potential intruders. Residents fed four prey per day suffered from a significantly higher number of take overs during the first day compared with larvae only fed two prey per day. The residents fed four prey per day stored some of the food in their nets making this resource more valuable also to intruders. After five days the number of take overs was about the same irrespective of previous treatment.