Spider Silk Protects Plants from Pests

Spider silk helps in protecting plants from insects, reveals a new study.

A team of researchers led by Dr Ann Rypstra from Miami University has found that spider silk acts as a pest repellent and prevents them from attacking plants, even if the spider is not present.

The research team examined two species of beetles - Japanese beetles (Popillia japonica) and Mexican bean beetles (Epilachna varivestis), which are eaten by web spiders. These two beetle species are green bean pests.

Experts carried out experiments with the beetles in the laboratory and outdoors. They applied two kinds of silk on the green bean plants. One from silkworms (Bombyx mori) and the other from a long-jawed spider (Tetragnatha elongata), reported LiveScience.

They found that the silk had great effect on the pest insects. In the lab, researchers noticed that both types of silk stopped the insects from damaging plants. But in field experiments, spider silk reduced plant damage by about 50 percent, but the silkworm silk led to only about 20 percent reduction in damages caused by the beetles. This suggests that the spider silk protects the plants from pest attack more effectively.

"These results provide robust support for the hypothesis that the presence of silk reduces the foraging activity of pest insects leading to lower levels of herbivory," the researchers wrote in the paper.

"Spider silk consistently had the strongest impact on leaf damage, whereas silkworm silk tended to have more modest effects," they said.

Researchers believe that chemical signals released by the silk stop the pests from attacking plants. They suggest that the chemical signal from spider silk is stronger and easier to detect when compared with signals from silkworm silk. This could explain why spider silk is more effective in stopping pest insects than silkworm silk.

Experts hope the study will help in developing applications in pest management and protect crops.

The findings of the study, "Spider silk reduces insect herbivory", are published in the Royal Society journal Biology Letters.