DNA sequencing of spider webs identified both the species of spider which created it and its prey in a new study. These new DNA techniques may replace previous approaches, improve species identification and allow monitoring of particular species leaving the spiders untouched and unobserved.
The spider may be a proven and integral organism within the ecosystem entitled to be preserved based on millions of years of co-evolution with other organisms. Fossil records suggest Spiders became established around 420 million years ago in the Silurian Period and spider webs have been revealed in fossils from around 318 million years ago, demonstrating how this ability may have evolved around this time. Of all the known spider species only one is herbivorous, the majority use the web to catch prey; commonly insects and other spiders.
The process of documenting spiders may provide important indicators of an ecosystems health, its habitat quality and any influence of man made particles. There are around 45,000 different known species of spider, with many new species still being discovered. This identification process may be challenging as many factors obscure the description of species, as spiders are normally identified through form and structure differences; particularly organs. DNA barcoding might reduce these challenges, reduce costs and identify species with greater accuracy than the human eye. Moreover, readily available cells are a healthy source of DNA as every one may contain thousands of mitochondria which also contain an independent source of DNA. In the past various ways of identifying and capturing spiders included shaking bushes, vacuuming, sweep netting, pitfall traps and visual cues although, many of these techniques may be detrimental to the spider. The techniques also lead to reduced species identification.
The importance of spiders to the ecosystem and the organisms’ omnipresent connection to man are fundamental considerations especially in some parts of the world. Particular species like the black widow spiders found in temperate regions may have venom 15 times stronger than a rattlesnake therefore, knowing the whereabouts of this spider is imperative. Finding a way to identify these spiders may support evasion of the black widow or other venomous species, protecting individuals worldwide and preserving the species from unnecessary interferences.
The new research by Xu and colleagues proposed a new bio monitoring tool which may compliment or replace previous methods utilising DNA acquisition from spider webs. This study is the first to assess spider webs as a possible source of DNA and to suggest spider and prey DNA may be collected from the web. The team used black widow spiders and house crickets and extracted the DNA of these species from the black widow’s cobweb, the DNA was then amplified and sequenced. The presence of spider and cricket DNA remained 88 days after the organisms were last in contact with the web giving evidence of further efficacy of the procedure. Charles Cong Xu lead author commented, “Sticky spider webs are natural DNA samplers, trapping nearby insects and other things blowing in the wind. We see potential for broad environmental monitoring because spiders build webs in so many places.”
Future DNA barcoding may provide further taxonomic information to identify many species of spider. An encouraging resolution of past challenges and detrimental effects on spiders may result and actually support the conservation of spider species. The research may have opened the possibility of technology identifying spider species for use in the home, by international shipping companies or pest management services. This may help protect families in some countries from particular species of spiders and lead to a greater peace of mind for individuals in the home.
How might knowledge of spider DNA support the wellbeing and numbers of spiders?