Typically DNA is extracted from live animals, but the process of capturing animals and extracting DNA isn’t always easy. For instance, spiders can be very mobile and difficult to catch. Spiders are also difficult to identify based on their appearance because there are so many species.
Scientists from the University of Notre Dame have found a much easier way of extracting DNA from spiders–from their webs. Similar methods of non-invasive DNA sampling have been used on things like fur that animals have shed or down feathers, but spider webs have never been used.
To test whether DNA could be extracted from spider webs, researchers used the webs of black widow spiders, which were from the Potawatomi zoo. Crickets, which are the normal food source of black widow spiders, were placed on the web to see if the DNA of prey could also be detected.
The team attempted to sequence portions of mitochondrial DNA in the spider webs made by the black widow spider. They did this by creating primers that detected a certain section of this part of DNA.
This proved successful and parts of this section of DNA were extracted. A similar method was also used to extract DNA from the crickets that were in the webs.
“The really cool part about our study is that we used non-invasive samples – so these web samples – where we don’t even have to directly observe or capture these spiders to get their DNA,” said Charles Xu, lead author of the study.
DNA extractions from spider webs could have huge implications in the study of spatial patterns of spiders. Spider webs are very abundant and easily collected, which could save a lot of time collecting live spiders.
By analyzing the DNA of spider webs in certain areas, scientists can now monitor where invasive or threatened spiders are located. According to the researchers, the range of endangered spiders is unknown. By taking DNA samples from webs, scientists can now find out where these endangered species are and how to stop their decline.
Spider web DNA can also be used to study the eating habits of spiders. If the DNA of a certain insect is consistently found on the web of the same species of spider, it can be inferred that this insect is the prey of the spider.