Guwahati: Entomophagy, the practice of eating insects, is a centuries-old tradition, particularly among indigenous communities worldwide. Approximately 2 billion people globally include insects in their diet, with over 2,000 species recognized as edible. In Northeast India, this practice is deeply rooted, with insects serving as a vital source of food, nutrition, and medicine.
Recent research conducted by a team of entomologists from the Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangalore, documented more than 500 species of edible insects in this region. This includes grasshoppers, caterpillars, beetles, termites, bees, wasps, ants, cicadas, and various aquatic insects.
The study underscores that several of these species, though widely consumed by ethnic communities, remain largely unrecognized or undocumented.
During the research, “stink bugs” sold in local markets during specific seasons attracted special attention from the researchers. Upon closer examination, these bugs were identified as members of the genus Coridius from the family Dinidoridae (Hemiptera). These bugs, ranging from 15-25 mm in size, primarily feed on plant sap. The genus Coridius consists of 35 species of phytophagous terrestrial bugs found in the Afrotropical and Indo-Malayan regions.
Due to the taxonomically complex nature of this genus, conventional taxonomic methods based on morphological characteristics were insufficient. The researchers, therefore, conducted an integrative taxonomic study combining phylogenetics, morphometric analysis, and classical taxonomy.
This comprehensive study led to the discovery of three new species and multiple undescribed lineages within this genus, which could potentially be new species. Additionally, the research facilitated the rediscovery of Coridius fuscus, Coridius laosanus, and Coridius assamensis, which had not been recorded for over a century.
The newly identified species were named to reflect their unique characteristics and the cultural significance of the communities in the region. Coridius adii was named in honor of the Adi tribe, one of the major groups inhabiting the Siang Valley, who traditionally consume this species. Another species, Coridius insperatus, which means “unexpected” in Latin, was named to reflect the surprise of its discovery.
This species is distinct from all others in its group, having only four segments to its antennae and cupreous dorsal coloration, whereas other species in the genus are typically dark brown, yellow to black dorsally, with five-segmented antennae.
A socio-economic survey conducted among the local communities revealed that while these bugs are popular delicacies, the consumption of darker-colored bugs is neurotoxic. Those affected exhibit photophobic behavior, such as hiding under carpets or beds, a behavior reminiscent of the bugs themselves, which hide under stones or in cracks.
Without medical treatment, these symptoms can persist for an extended period. The researchers identified this neurotoxic bug as a new species, naming it Coridius esculentus. Furthermore, another bug, now identified as Coridius chinensis, was reported to cause dizziness, nausea, and vomiting in some individuals, potentially leading to a loss of strength and semi-consciousness.
The research team, led by Dr. Priyadarsanan Dharma Rajan, included Swapnil Boyane, Dr. Sandeep Sen, and Pavan Kumar Thunga from ATREE in Bengaluru, along with Dr. Hemant Ghate from Modern College, Pune.
Their findings were published in the recent issue of the open-access journal PLOS ONE.
“Entomophagy, or the practice of eating insects, is an age-old tradition widely practiced in Northeast India, where many communities rely on insects as a source of food, nutrition, and medicine.
Our findings are significant as they have important implications for public health, conservation, and engaging diverse audiences, including scientists, park managers, media, and the general public,” said Dr. Priyadarsanan Dharma Rajan, the senior author of the paper.
Northeast India, a major biodiversity hotspot, is home to over 500 tribes of different ethnic groups, each with distinct cultural identities and rich indigenous knowledge systems.
These communities have long relied on various components of biodiversity for their daily sustenance, including food, fodder, shelter, and healthcare.
“Many of these resources, despite their widespread use by traditional communities, have not been scientifically surveyed. People here have used insects and snails in varied ways, including for edible, medicinal, industrial, and cultural purposes. However, there is a serious threat of erosion and even complete loss of this valuable knowledge unless effective measures are taken to codify and protect it,” added Dr. Priyadarsanan.
The discovery of Coridius adii, Coridius esculentus, and Coridius insperatus suggests that many more species are yet to be described from this region, opening new avenues for scientific exploration and conservation efforts.
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