Silk Landscapes of India: How Climate, Topography, and Host-Plant Ecology Shape Indigenous Sericulture

印度丝绸版图：气候、地形与寄主植物生态如何塑造本土蚕桑业

Wang Yixuan1, Li Silong2

1. School of Foreign Language Studies, Zhejiang Sci-Tech University, Hangzhou 310018, China;

2. School of Humanities & Foreign Languages, Zhejiang Shuren University, Hangzhou 310015, China

Abstract:India, the world's second-largest producer of silk and the only country capable of simultaneously producing mulberry, tasar, eri, and muga silk, boasts a unique silk industry shaped by its complex and diverse physical geography. This study systematically analyzes the intrinsic relationships between key geographical factors—climate, topography, and vegetation—and India's major indigenous silk varieties. Available evidence suggests that climate, primarily through temperature and precipitation, macroscopically determines the voltinism of silkworms and the distribution of major production regions. For instance, the abundant rainfall from the southwest monsoon plays a crucial role in forming the prominent mulberry sericulture hub in southern India, often referred to as the "southern triangle." In contrast, topography, through factors such as elevation and slope aspect, influences the distribution of specific host plants (e.g., Machilus gamblei and Litsea monopetala at different altitudes), thereby delineating the ecological niches for wild silkworm species like tasar and muga. The diverse range of India's indigenous silk varieties is a direct reflection of its physical geography, which also shapes the industrial structure. The synergistic interaction of these factors has collectively contributed to the highly concentrated yet distinctly specialized geographical distribution of the country's silk industry.

Key words:India; silk; physical geography; climate; topography; host plants

Author:Wang Yixuan (2002–), male, master's student, main research interest in English translation.

1 Introduction

The production of India's major silk types is highly concentrated and regionally specialized. Mulberry silk production is predominantly centered in the south, tasar silk is concentrated in central and northern regions, while eri and muga silk production is largely distributed across the northeastern states, with Assam serving as the principal hub[1]. This distribution pattern is a direct outcome of India's distinctive natural environment. The country's predominantly warm conditions, with most regions characterized by a subtropical monsoon climate, contribute to the widespread prevalence of multivoltine silkworm races. In addition, specific topographic conditions restrict the cultivation of host plants such as mulberry and castor, thereby shaping the geographical extent of sericulture activities. Regional vegetation types further influence the production of wild silks, including tasar.

This study seeks to systematically examine the intrinsic relationships between India's key physical geographical elements—namely climate, topography, and vegetation—and its major indigenous silk types. By analyzing these core geographic characteristics, the research aims to elucidate the synergistic role these factors play in shaping the distinct spatial distribution patterns of India's various silk industries, thereby providing an economic-geographical perspective on the formation and development of regional specialty products.

2Overview of India's physical geography and silk resources

India, a vast landmass occupying much of the South Asian subcontinent, possesses a complex and highly diversified physical environment that forms the ecological foundation of its distinctive silk industry. To better understand the spatial distribution and biological characteristics of India's indigenous silk types, it is essential to first examine the key geographical elements upon which sericulture depends—climate, topography, and vegetation.

2.1 Physical geographical characteristics

Although India is generally characterized by a tropical monsoon climate, the climate varies substantially across regions due to pronounced topographic conditions[2]. These spatial variations in temperature and precipitation directly influence the distribution of silkworm host plants, thereby shaping regional sericultural systems.

The southwest monsoon delivers the majority of India's annual rainfall, but its effects are markedly uneven. Orographic uplift along the Western Ghats produces extraordinarily high precipitation on their windward slopes, often exceeding 4,000 mm per year[3]. The Deccan Plateau, flanked by the Eastern and Western Ghats, intercepts moisture-laden winds from both the Arabian Sea and the Bay of Bengal. While this orographic effect generates rainfall along the plateau margins, the interior experiences comparatively reduced precipitation due to the subsidence associated with the subtropical high-pressure belt. Nevertheless, rainfall in most central regions remains sufficient to sustain extensive agricultural and forestry development. These sharp gradients in moisture availability delineate distinct ecological niches for different silkworm host plants.India's topography can be broadly divided into three major units: the Himalayan mountain system in the north, the Indo-Gangetic Plain in the center, and the Deccan Plateau in the south. The towering Himalayas function as a formidable climatic barrier, blocking cold continental air masses and giving rise to unique temperate vegetation zones along their foothills. South of the mountains lies the Indo-Gangetic Plain, a vast, low-lying, and fertile alluvial region that forms the core of India's agricultural productivity. Further south, the Deccan Plateau occupies most of the peninsular landmass. Although its soils and water resources are generally less favorable than those of the alluvial plains, the plateau's undulating terrain combined with a monsoonal climate supports a wide variety of crops and natural vegetation types.

The interplay of India's climate and topography has produced distinct physical geographical patterns, which in turn have significantly influenced the spatial distribution of host plants essential for silkworm cultivation. The tropical monsoon climate provides the fundamental hydrothermal conditions, while the Himalayan barrier effect, the plains'tendency to concentrate water and soil resources, and the plateau's orographic and rain-shadow effects collectively generate further regional disparities in precipitation and temperature. These differentiated ecological environments ultimately determine the suitability of various host plants, thereby forming the physical geographical basis for the development of India's diversified silk industry.

2.2 Major silk resourcesAs the world's second-largest silk producer, India maintains an exceptionally diversified sericultural profile. Beyond mulberry silk—the predominant variety in global production—India uniquely sustains several indigenous wild silks, including muga, eri, and tasar, thereby supporting a distinctly multi-species silk industry.

Tab. 1 Production Share of Major Silk Varieties in India (2023‒24)

The muga silkworm (Antheraea assamensis), renowned for producing the lustrous "golden silk,"is endemic to Assam and neighboring northeastern states and is revered as the "Queen of World Silk."The term muga, derived from Assamese, refers to the amber hue of its cocoons. Muga silkworms feed primarily on Machilus gamblei and Litsea monopetala, host plants that thrive in the humid subtropical climate of northeastern India at elevations around 1500 feet. Assam remains the principal production center, yielding approximately 252 tons annually. To support this unique industry, the Central Silk Board of India has established specialized research and training institutions in the region[1].

Eri silk—also known as errandi—derives its name from its primary host plant, the castor (Ricinus communis). Because eri cocoons cannot be reeled into continuous filaments, they are predominantly processed into spun silk yarn, from which textiles with distinctly Indian aesthetic and cultural characteristics are produced. India is the world's largest producer of eri silk, with output rising from approximately 6,946 tons in 2020 to 7,183 tons in 2023–24[1]. In recent years, the country has also actively promoted the development of eri-silk blended fabrics, which have achieved strong acceptance in domestic and international markets[1].

India's tasar silkworms are categorized into tropical and temperate ecotypes, with the tropical tasar silkworm (Antheraea mylitta) serving as the primary source of production. This species feeds predominantly on tropical almond(Terminalia catappa L.). India produced approximately 1586 tons of tasar silk in 2023–24, with major production zones concentrated in the Central–Chhattisgarh and Bihar–Jharkhand belts[1].

Mulberry silk is the largest silk variety produced in India by volume. The country cultivates a diverse range of mulberry silkworm (Bombyx mori) breeds, broadly classified into yellow-cocoon and white-cocoon varieties. Based on the type of reeling equipment employed, raw silk generated from these cocoons is primarily categorized into three groups: hand-reeled silk, cottage-basin silk, and filature silk[1]. Mulberry sericulture in India is heavily concentrated in the "southern triangle,"comprising the states of Karnataka, Andhra Pradesh, and Tamil Nadu. This region overwhelmingly leads the nation in mulberry acreage, the number of silkworm seed dfls (disease-free layings) produced and utilized, and overall raw silk output[1].

Tab.2Contribution of Southern States to India's sericulture sector (area, DFLs, and raw silk production)

The unique silk varieties of India have developed in harmony with the country's diverse physical environment, adapting to local climatic, topographical, and vegetation conditions over time. This deep connection between silkworm species and their ecosystems has led to distinct regional patterns in silk production, where each variety thrives within specific ecological niches. As we move into the next chapter, we explore the crucial role that climate plays in shaping the geography of India's silk industry, followed by an examination of how topography and vegetation further refine the distribution of these indigenous silk varieties. Together, these environmental factors form the foundational constraints that govern the spatial concentration and specialization of sericulture practices across the country.

3Influence of the natural environment on indigenous silk varieties and their spatial distribution

India's indigenous silk varieties are deeply embedded in the country's heterogeneous physical environment. Over long periods of evolution and adaptation, different silkworm species—and, crucially, their host plants—have developed distinct regional ecological requirements in response to local climates, landforms, and vegetation structures. These biological constraints, interacting with human production practices and historically rooted livelihood systems, have ultimately produced the highly specialized and regionally concentrated geography of India's silk industry.

3.1 The decisive role of climate

Climate is the most fundamental component of the physical geographical environment shaping sericulture, because it directly influences silkworm physiology and determines the availability and phenology of host plants. Through temperature, humidity, and precipitation regimes, climate controls silkworm voltinism (the number of generations per year), rearing calendars, and the broader spatial boundaries within which different silk varieties can be produced.

Situated largely within tropical and subtropical monsoon climatic zones, much of India permits sericulture for extended periods of the year. Consequently, indigenous silkworm races in many regions are predominantly multivoltine, capable of completing multiple generations annually. For instance, the muga silkworm in Assam may complete approximately five to six generations per year, while eri silkworms generally exhibit little or no diapause, enabling flexible rearing schedules. By contrast, bivoltine mulberry silkworm varieties are comparatively sensitive to thermal stress and are therefore concentrated in relatively cooler northern areas or are reared during the cool season in southern India; as a result, both their spatial distribution and production cycles are more strictly constrained[4].

Spatial contrasts in precipitation and humidity further refine India's sericultural geography. Along the windward slopes of the Western Ghats, strong southwest-monsoon influence generates extremely high rainfall and persistent atmospheric moisture, conditions that support vigorous mulberry growth. This monsoon-fed hydrothermal regime helps underpin the dominance of the southern mulberry sericulture core—often described as the "southern triangle,"centered on Karnataka, Andhra Pradesh, and Tamil Nadu. In northeastern India, the host plants of the muga silkworm (e.g., Litsea monopetala) favor warm and humid conditions and are widely distributed in low-elevation hill environments. Accordingly, the humid, seasonally moderate hill climate of the Northeast provides an ecological fit for muga host-plant growth and silkworm rearing, fundamentally limiting muga production to this region[5].

3.2 Topography and vegetation as foundational constraints

Within the broader climatic envelope, topography and vegetation impose additional constraints by shaping microclimates and—most importantly—by delimiting the distribution of silkworm host plants. Elevation, slope position, and aspect influence temperature gradients, soil moisture, and sunlight exposure, thereby determining where suitable host-plant communities can persist. These relationships are particularly pronounced for wild and semi-domesticated silks, whose production remains closely tied to natural forest ecosystems.

Topography restricts host-plant ranges in ways that are especially evident in oak tasar silkworms, which depend on altitudinally zoned oak forests. In India, oak tasar cultivation is associated with multiple oak species distributed across distinct elevation belts—for example, Quercus incana (approximately 1,200–2,500m), Quercus semecarpifolia (approximately 2,500–3,500m), and Quercus serrata (approximately 600–1,800m)[6]. These elevation-defined forest belts generate differentiated microclimates and host-plant phenologies. In turn, they determine not only the spatial extent of oak tasar rearing but also its seasonal management strategies—for instance, winter de-budding practices in certain belts to stimulate earlier leaf flushing and better synchronize host-plant availability with silkworm growth.

A similar pattern is observed in muga production, where the principal host plants show marked sensitivity to terrain-related hydrothermal conditions. Two key host species—Machilus gamblei and Litsea monopetala—exhibit pronounced topographic preferences. The suitability of Machilus gamblei, for example, varies by slope position, with lower slope locations often providing more favorable moisture and nutrient conditions for growth[7]. As a consequence, high-quality muga rearing sites tend to cluster in well-watered landscape settings such as lower valley slopes. Litsea monopetala is likewise associated with sunny slopes in low-elevation hill terrain, further narrowing the geographical range in which stable muga production can be sustained.

India's silk-producing regions are structured by a layered set of environmental controls. At the broadest scale, climate—especially thermal conditions and monsoon-driven moisture regimes—defines the feasible limits of sericulture by shaping silkworm voltinism, rearing windows, and the seasonal reliability of host-plant resources. Within this climatic framework, topography and vegetation further differentiate production spaces by creating distinct microclimates and, more critically, by constraining the distribution and phenology of specific host plants. This is most evident in wild and semi-domesticated silkworms'cultivation, such as tasar and muga, where rearing is tightly coupled to altitude-dependent forest belts and terrain-conditioned host-plant habitats. These factors explain why India's silk industry exhibits both high spatial concentration (e.g., the southern mulberry core and the Northeast muga zone) and strong regional specialization, with each silk type occupying ecological niches defined by the intersection of climate suitability and host-plant geography.

4Contemporary challenges and future pathways for India's silk industry

The preceding analysis has shown that the distinctive geographic patterns of India's silk production—from the mulberry-rich "southern triangle"to the muga-bearing hills of Assam—are deeply rooted in the subcontinent's physical environment. Over centuries, sericulture has evolved through close adaptation to climate, topography, and vegetation, creating an industry whose strengths and vulnerabilities are inseparable from its ecological setting. Yet this historically resilient, ecology-dependent sector now operates in an increasingly unstable landscape. It confronts a range of contemporary pressures that challenge the endurance of traditional models while also opening the door to meaningful transformation. These pressures include the effects of climate change, socio-economic constraints, the demands of global markets, and shifting consumer expectations. This final chapter examines the core challenges facing India's silk industry and explores the integrated strategies—spanning ecological stewardship, social policy, technological progress, and international cooperation—that are shaping its future direction.

4.1 Navigating contemporary challenges: from ecological pressures to global markets

India's silk industry has long flourished by specializing within distinct ecological niches, such as the mulberry-dominated south and the muga-producing regions of Assam. Today, however, the delicate balance between geography and production is increasingly strained by multiple, overlapping disruptions.

Sericulture's dependence on highly specific climatic conditions and host plants makes it acutely vulnerable to environmental change. Altered monsoon cycles, unseasonal rains, prolonged droughts, and rising temperatures threaten the alignment between silkworm growth stages and the seasonal rhythms of their host plants. These disruptions jeopardize both yield and quality, particularly for wild silks like tasar and muga. Human-driven pressures—such as habitat fragmentation and unsustainable extraction of key host species like Machilus gamblei and Litsea monopetala—further erode the ecological foundations on which these industries rely.

At the community level, the sector struggles with issues of scale, productivity, and rural livelihood security. Sericulture in India is dominated by small, fragmented holdings that limit investment in improved technologies and infrastructure. Despite being the world's second-largest silk producer, the country continues to face a significant deficit in high-quality raw silk for power looms, prompting reliance on imports—especially from China. This gap highlights the urgent need to enhance domestic yarn quality, consistency, and cost competitiveness.

India's unique silk traditions must also contend with commoditization and threats to intellectual property. Global trade has heightened competition from mass-manufactured textiles while exposing heritage-rich products to misappropriation and counterfeiting. Past experiences—such as the disputes surrounding Basmati rice and turmeric—demonstrate the necessity of robust legal mechanisms to protect culturally significant products. Without systematic documentation and enforceable intellectual property rights, iconic silk types like Kanchipuram, Mysore, and Muga risk losing both market value and cultural identity.

4.2 Strategic Pathways: integrating sustainability, innovation, and governance

Meeting these challenges requires a comprehensive strategy that weaves together ecological sustainability, technological advancement, socio-economic development, and effective governance. Such an approach not only addresses the sector's immediate vulnerabilities but also lays the groundwork for long-term resilience.

The future of Indian sericulture depends on adopting practices that reduce environmental impact while improving productivity. For mulberry silk, this includes promoting water-efficient irrigation, integrated pest management, and organic cultivation methods. For wild silks, in-situ conservation of host plant ecosystems and sustainable harvesting protocols are essential. At the same time, research into climate-resilient silkworm breeds—such as thermotolerant bivoltine mulberry strains and disease-resistant muga varieties—will be critical for maintaining stability as environmental conditions fluctuate.

Value addition and vertical integration offer another pathway toward resilience and profitability. Small-scale, decentralized processing units—such as charkha-based spinning for eri silk—can generate income while preserving traditional craftsmanship. Furthermore, expanding the use of Geographical Indications (GI) for products like "ASSAM muga silk"and"KANCHIPURAM silk",can safeguard cultural heritage and strengthen market identity. GI certification not only provides legal protection but also enhancesbrand value and enables premium pricing, benefiting artisans, producers, and consumers alike.

5Conclusion

This study shows that the geography of India's silk industry has been shaped by a long interplay between natural conditions and human craftsmanship. The monsoon rains carve out the mulberry-growing regions of the south, the rising slopes of the central highlands determine where tasar thrives, and the humid valleys of the northeast nurture the golden muga. Together, this environmental diversity and deep reservoir of traditional knowledge have produced an unmatched variety of silk textiles—fabrics that carry both economic worth and cultural meaning.

Yet the industry now faces challenges that call for a fresh approach. The way forward is not to discard the geographical specializations that define Indian sericulture, but to strengthen and adapt them for a changing world. To remain competitive, the industry must pair its ecological strengths with technological innovation and broader market strategies. Scientific conservation, climate-resilient practices, and the safeguarding of intellectual property can help India shift from a focus on volume to a leadership position in sustainable, high-value, culturally grounded silk production.

Ultimately, the goal is to ensure that the golden sheen of muga, the textured depth of tasar, the comforting softness of eri, and the classic lustre of mulberry continue to create not only exquisite textiles but also secure livelihoods and a resilient cultural identity for generations to come. Like the fibre itself—strong, adaptable, and enduring—the future of India's silk industry will depend on its ability to evolve while remaining true to its roots.

Reference

[1] LI L. Studies on Sericulture Development in India[D]. Chongqing: Southwest University, 2008.

[2] SPATE OHK, LEARMONTH ATA. India and Pakistan: A General and Regional Geography[M]. London: Routledge,2017.

[3] VENKATESH B, NAYAK PC, THOMAS T, et al. Spatio-temporal analysis of rainfall pattern in the Western Ghats region of India[J]. Meteorol Atmos Phys, 2021, 133, 1089–1109.

[4] DONG ZP, WU KJ, YANG W, DING SM, LUO K, SHEN ZL, CHEN S. Mulberry Silkworm Rearing Methods in India[J]. Bulletin of Sericulture, 2005, (3), 69-71.

[5] ZHONG J, JIANG X J, YAO L P, ZHU S F, LIAO P F. Rearing Techniques of Indian Amber Silkworm[J]. China Sericulture, 2012, 33(4), 18-21.

[6] ZOU T. Rearing of Indian Tussah Silkworm[J]. Liaoning Silk, 2003, (2), 23-25.

[7] DING S F. Study on Germplasm Resource Characteristics of Machilus Gamblei in Guangdong Area[D]. South China Agricultural University, 2019.

[8] MOT, Government of India. Annual Report 2022‒23[R]. Bengaluru: Central Silk Board, 2022.

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