ZSI scientists use DNA metabarcoding to uncover hidden enemies of spider eggs

Kolkata, May 8 (PTI) We all know spiders catch insects, but now scientists from the Zoological Survey of India (ZSI) have discovered that even spiders eggs have their own tiny enemies — creatures so small, we usually can't see them.

A team of ZSI scientists used an advanced method called DNA metabarcoding to identify which tiny organisms attack spider eggs.

This is the first time anyone in the world has used this advanced technique to study these relationships directly from spider egg sacs, Dr. Rupam Debnath, a member of the team, told PTI on Thursday.

Spider egg sacs are protective, silken pouches created by female spiders to hold their eggs.

Led by Dr K Rajmohana, the team also includes V Sushama and Dr KP Dinesh.

Metabarcoding is a technique which allows simultaneous identification of multiple species within a single sample by analyzing DNA sequences from a set of genes which is different from traditional DNA barcoding which focuses on identification of individual species.

Using this DNA-based approach, the scientists discovered tiny, wasp-like creatures — Idris, Odontacolus and Baeus — living on spider eggs, the ZSI said in a statement.

"These tiny enemies are usually hard to find because they are smaller than a millimeter. You can't easily see them unless you spend a lot of time watching them closely under a microscope," Debnath explained.

"We hope by using this methodology and protocol, researchers will be able to explore hidden ecological relationships between insects and spiders the world over," he added.

"Using DNA metabarcoding helped us find new connections between spiders and their enemies that we wouldn't have found using old methods. It's like uncovering a hidden world," Debnath said.

Dr. Rajmohana elaborated that DNA metabarcoding is a powerful tool that reveals all the tiny organisms present in a sample—without the need to raise them in a lab.

"This method works best when we already know a lot about these creatures through traditional ways of studying them," the senior scientist said.

Sushama added, "This work helps us understand nature faster and shows us how surprisingly complex it is." The team even identified an unexpected insect, Aphanogmus, in the spider egg sacs.

"This shows that different creatures in nature are connected in more ways than we think," she said.

According to Debnath, the team analysed over two million DNA sequences and identified 28 different types of small creatures — 14 of which were confirmed as tiny enemies attacking spider eggs.

This DNA method also revealed information about what the mother spiders had been eating, giving a better picture of the food chain system.

"We will now focus on building better DNA libraries for these tiny wasps and spiders. This will help researchers identify these creatures more accurately in the future and keep a better eye on the health of our ecosystems," Suresh said.

ZSI Director Dr. Dhriti Banerjee congratulated the team, saying that "understanding how different living things are connected is important for nature." PTI SUS MNB