PARENT SESSION
Poster Session 24: Agro-Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Silk reduces plant damage caused by pest insects.

Rypstra, Ann^*,1, Buddle, Christopher², ¹ Miami University, Hamilton, Ohio, USA² McGill University, Montreal, Quebec, Canada

ABSTRACT- Spiders dominate the terrestrial predatory arthropod community and can have strong effects on potential prey even in situations where there is no possibility of predation. Since spiders are ubiquitous predators and they all produce silk, we explored whether the silk dragline could serve as a signal causing pest insects to reduce their activity or relocate. We hypothesized spiders could reduce plant damage caused by herbivores if the insects reacted to the silk left behind by the spider. We applied freshly produced spider silk and commercially available silkworm silk to snap bean leaves enclosed with either Japanese Beetles or Mexican bean beetles in the laboratory and in field enclosures. In addition, we applied both types of silk to individual leaves of unenclosed leaves in the field. In separate experiments we applied silkworm silk to all the leaves of an entire plant and either enclosed the plant with beetles or left it exposed so that it could experience natural herbivory. In all cases, leaves treated with experienced less leaf damage. These results suggest that silk may be an important signal to insects that a predator is foraging in the area. Thus, silk may play an important role in integrated pest management or biological control.

Key words: silk, spiders, herbivory, indirect effects