Feeding mediated web-building plasticity in a cobweb spider

We studied state-dependent web-building plasticity in cobweb spider Campanicola campanulata by manipulating food intake of adult females. We set up three spider groups with different feeding conditions: hungry, control and well-fed, and observed the differences of the web architectures in different groups. In addition, we measured the mechanical properties of anchor silk, and also calculated the foraging and behavioral investment of the spiders during web construction in different group. The results showed that hungry spiders build cobwebs with significantly longer length of anchor silk, lower retreat, more number and longer gumfooted lines, and larger capture area, while well-fed spiders build cobwebs with significantly bigger volume of retreat and higher height of retreat to the ground. In addition, hungry spiders spend significantly lower energy expenditure during the cobweb construction. However, there are no significant difference between the breaking force and elongation at break in anchor silk among different groups. These results demonstrated that hungry spider put more energy into foraging, and well-fed spider put more energy into defense, and the spider trades off between foraging and safety in response to changes in physiological state