The Impact of Climate Change on Tea Plantations in South Asia
As global temperatures rise, tea estates in Bangladesh and India are facing unprecedented challenges. Extended summers, delayed monsoons, and shorter winters are contributing to a surge in pest infestations, threatening a crucial industry in two of the world’s largest tea-producing nations.
Entomologists have observed a marked increase in pests such as red spider mites (Oligonychus coffeae) and thrips (Scirtothrips dorsalis), which were previously minor concerns. Additionally, the resurgence of looper caterpillars (Biston suppressaria) has been noted, exacerbating the situation for tea growers.
The vulnerability of tea plants (Camellia sinensis) to pests is well-documented, with researchers in both countries sounding the alarm over the growing prevalence of tea mosquito bugs (Helopeltis theivora), red coffee borers (Zeuzera coffeae), green weevils (Hypomeces pulviger), and red slug caterpillars (Eterusia aedea).
Mohammad Shameem Al Mamun, a principal scientific officer at the Bangladesh Tea Research Institute, highlighted the changing pest dynamics due to rising temperatures. “Due to rising temperatures, pest infestation is increasing as well as pest status is changing,” he noted in a recent interview with Mongabay.
Data from the Bangladesh Tea Association reveals a decrease in average maximum daytime temperatures in the Sylhet region from 33.9°C to 31.2°C over the past decade, while nighttime temperatures have increased from about 16°C to 20.7°C.
In 2024, Bangladesh produced 93 million kilograms of processed tea, a decline from 102.9 million kilograms the previous year. This decrease mirrors a larger trend seen in India, where tea production fell from 1.4 billion kilograms to 1.3 billion kilograms.
Pest Challenges in Tea Gardens
The economic impact of these pest infestations is significant. According to a local news report, pests like looper caterpillars cost India’s tea industry approximately 147 million kilograms of tea annually, equating to a financial loss of around 28.65 billion rupees ($318 million).
Joydeep Phukan of the Tea Research Association of India notes that tea plantations, especially in Assam and West Bengal, are experiencing longer summers with temperatures reaching 35-40°C. This contributes to the increase in pest populations.
Phukan emphasized the importance of temperatures around 25°C for optimal tea cultivation, a condition increasingly rare due to climate change.
Integrated Solutions and Soil Health
With traditional pesticides losing effectiveness, experts advocate for integrated pest management (IPM) strategies. These include cultural control methods like plucking and pruning, shade regulation, and the use of pest-resistant plant varieties.
Shameem’s research suggests that mechanical methods, such as manual pest removal and biopesticides, could play a crucial role in managing infestations.
In addition to IPM, improving soil health is essential. Joydeep Phukan points out that the intensive monoculture in tea plantations has depleted soil quality. The introduction of biochar, a nutrient-rich soil additive, is one proposed solution to enhance soil health over a five-year period.
Building a comprehensive data hub on pesticide use and pest management across Bangladesh, India, and Sri Lanka is another recommended measure to help the industry adapt to climate change.
Despite facing different environmental challenges, Sri Lanka’s tea industry is recognized for its clean production practices, maintaining low pesticide residues while employing IPM techniques. This approach has helped Sri Lanka maintain a reputation for high-quality tea on the global market.
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Original Story at news.mongabay.com