Feeding mediated web-building plasticity in a cobweb spider.

Area of Science:

• Animal Behavior
• Ecology
• Arachnology

Background:

• Behavioral plasticity allows animals to adjust phenotypes to environmental changes.
• Cobweb spiders like Campanicola campanulata offer a model for studying web architecture plasticity.
• Retreat construction in cobweb spiders is often overlooked despite its defensive role.

Purpose of the Study:

• To investigate how feeding regimes influence web architecture and investment in foraging versus defense in C. campanulata.
• To quantify differences in web structure, mechanical properties, and resource allocation under varying nutritional states.

Main Methods:

• Campanicula campanulata spiders were divided into three feeding groups: marginally, moderately, and extremely well-fed.
• Web architecture, including retreat size and silk length, was measured.
• Mechanical properties of anchor silk were tested, and investment in foraging and defense was calculated.

Main Results:

• Marginally fed spiders built webs with longer anchor silk, more gumfooted lines, and larger capture areas, indicating increased foraging investment.
• Extremely well-fed spiders constructed larger retreats positioned higher off the ground, suggesting greater defense investment.
• No significant differences were found in the breaking force or elongation at break of anchor silk.

Conclusions:

• Campanicula campanulata exhibits behavioral plasticity, balancing foraging and defense investments based on nutritional status.
• Resource allocation shifts towards foraging when food is scarce and towards defense when food is abundant.
• This study enhances understanding of web construction costs and adaptive strategies in cobweb spiders.