ZSI study decodes spider-parasitoid association through DNA metabarcoding

Our CorrespondentKolkata: A new study by scientists from Zoological Survey of India (ZSI) has uncovered a hidden dimension in spiders, usually celebrated as formidable predators revealing that even they have their tiny, unseen adversaries.

A team from the ZSI led by K Rajmohana and comprising Rupam Debnath, V Sushama and KP Dinesh has achieved a landmark scientific breakthrough by applying DNA metabarcoding to decode spider-parasitoid associations directly from spider egg sacs. Through DNA metabarcoding, the study recovered spider egg parasitoids such as Idris, Odontacolus and Baeus species. These groups remain generally underexplored due to their minute size — often less than a millimeter — making them extremely difficult to detect unless specifically targeted through detailed rearing or microscopic examination.

The study has been published in the globally reputed journal ‘Scientific Reports’, marking the first-ever attempt worldwide to uncover these associations using high-throughput sequencing.

Dhriti Banerjee, director of ZSI, said: “Sustainability begins with understanding the intricate web of life.

This groundbreaking work is a proud moment for Indian science. Employing modern tools like DNA metabarcoding to explore hidden ecological relationships reflects our commitment at ZSI to cutting-edge biodiversity research.”

K Rajmohana emphasised: “DNA metabarcoding is a revolutionary tool that allows us to unravel the full suite of organisms associated with a sample without relying solely on traditional rearing.

However, its true power is realised when it builds upon strong foundations laid by conventional approaches — detailed morphological studies, traditional rearing methods, and classical DNA barcoding. Once these pillars are strengthened, DNA metabarcoding can yield even deeper, more accurate insights into ecological interactions

and biodiversity.”

The team analysed over two million DNA reads, leading to the identification of 28 arthropod taxa, with 14 representing direct host-parasitoid associations.

They also demonstrated the ability of DNA metabarcoding to detect broader trophic interactions, including prey items transported by mother spiders, offering a fuller view of food web structures.

This achievement not only places Indian scientists at the forefront of global ecological research but also opens exciting new avenues for using molecular tools to explore, conserve and understand the hidden workings of nature’s fragile and fascinating networks.