Posted by: Glow-worm PJ29 JAN 2014
Recent research has shown that the presence of electrostatically charged, conductive glue on the silk of spiders’ webs causes them to move towards prey. Flying insects build up a positive electrostatic charge through the friction of their wings against air molecules, sufficient for the insects to draw pollen from a flower before it has actually alighted. It is thought that these naturally occurring charges may have driven the evolution of specialised webs.
Many insects use their antennae as so-called e-sensors to detect small electrical disturbances, for example, to detect other insects and different flowers. The tips of the antennae are separated from the insect’s body by insulating material, which means that the charge at the tips of the antennae is different from that of the rest of the insect. The presence of electrical charges causes the tips of the antennae to move slightly, and this movement can be sensed and interpreted by the insect. It is also thought that, as well as using their antennae to detect flowers and other insects, they are able to utilise them to avoid becoming ensnared in charged spiders’ webs.
It has also been shown that these charged webs attract not only prey, but also pollen and other pollutants such as aerosols and pesticides. They filter airborne pollutants with an efficiency comparable to expensive industrial sensors, and it has been suggested that the webs could used for environmental monitoring by being harvested and tested for pollution levels, for example of pesticides, suspected of harming insect pollinators.
The manner in which the webs collect pollen and dirt may also explain why certain species of spider rebuild their webs on a daily basis, irrespective of whether they appear physically damaged, or contain prey.