Tea Research Association

Aim: To investigate the extent of insecticide resistance in H. theivora within Assam's tea-growing areas and to understand the defence mechanism that contribute to its development. Methodology: Adult population of H. theivora from an organic tea plantation were collected for susceptible laboratory culture and other seven adult populations were collected from major tea-growing parts of Assam following conventional practices and reared under controlled laboratory conditions. The leaf dip method was used to conduct concentration mortality bioassays with thiamethoxam, deltamethrin and quinalphos. Biochemical assays were carried out to assess the activity of major detoxifying enzymes in the insects, including general esterases involved in hydrolysis, oxidative enzymes of cytochrome P450 family, and transferases that conjugate glutathione to xenobiotics. Furthermore, synergistic assays with piperonyl butoxide and diethyl maleate were carried out to evaluate their influence on the efficacy of insecticides. Results: Resistance to thiamethoxam and deltamethrin was quite significant, with resistance coefficients ranging 2.04-22.14 and 1.56-23.90 times, respectively. All tested populations remained susceptible to quinalphos (RC<1). Increased enzyme activities exhibited a strong positive correlation with LC50 values, while the use of synergists significantly improved the insecticide efficacy. Interpretation: The findings highlight the field-evolved resistance in H. theivora and its association with elevated detoxifying enzymes. This study recommends the strategic use of insecticides, rotation, and synergists for better resistance management, contributing to more sustainable pest control in tea plantations. Key words: Esterase, H. theivora, Insecticides, Tea mosquito bug

Sewage water and sludge provide a viable option to meet crop water and nutrient demands in the face of rising climatic stress. Thus, a 2-year field study (2018 and 2019) was conducted to evaluate the effect of sewage water and sludge on soil properties and the growth response of green chili. The experiment comprised nine treatment combinations involving three types of irrigation water: normal water (I 1 ), treated sewage water (I 2 ), untreated sewage water (I 3 ) along with three soil amendments: farmyard manure (FYM) at 25 t ha −1 (SA 1 ), sewage sludge at 25 t ha −1 (SA 2 ), and a mix of sewage sludge at 12.5 t ha −1 + FYM at 12.5 t ha −1 (SA 3 ). Soil-available nutrient status of N, P, and K increased by ˜10%–15%, ˜14%–20%, and ˜13%–18%, respectively, in I 3 and SA 2 . Sewage water and sludge application further improved soil microbial populations, which included actinomycetes, fungi, and bacteria. Concurrently, multivariate analysis of variance (MANOVA) demonstrated a positive influence of irrigation and soil amendments on soil properties. Across both study years, I 3 and SA 2 recorded a higher mean green chili yield, with an improvement of approximately 25% over I 1 and SA 1 . Hence, the findings reveal the feasibility of harnessing sewage water resources as sustainable inputs, advancing both resource efficiency and short-term agricultural sustainability in the region.

One of the major findings of the research on the development and growth of the tea plantations in colonial Assam has been the consistency in implications of the British planters’ scientific knowledge in converting the wild periphery of the distant part of the newly annexed territory into the edenic manifestation of a garden .But we delve deeper into the historical background of the production of tea as one of the major mercantile goods in terms of its capacity to occupy a very respectable position in the world of commerce for the interests of the British colonial empire then we could see that it was the Chinese methods of scientific production of tea that was deployed in generating the knowledge about the further growth of tea cultivation in Assam. It was not the British science that was assumed to be the catalyst of making Assam a safe haven for increasing rate of export of tea instead of the Chinese import of tea but it was the art of scientific knowledge of producing tea which was utilized through the mercantile skill of the British tea entrepreneurs The paper would try to analyze how the British colonial state took help in the initial stage of production of tea from the Chinese experts in order to consolidate the hold over the methods of cultivation of tea in a more appropriate way .In today’s perspective , the chai diplomacy has a great leverage in increasing strong diplomatic relation of the Indian republic with the South East Asian countries through coming out of the colonial hangovers.

Tea is the most consumed beverage worldwide and is renowned for numerous health benefits. However, potentially toxic elements (PTEs) in tea leaves are a global concern. This study evaluates the bioavailability of PTEs in tea soils, their transfer to leaves and infusions, analyzing 100 samples from four different tea-growing zones in North Bengal, India. In zone 1 (North Dinajpur) the average transfer rate of Cr, Ni, Cu, Zn, and Pb from leaves to infusion were 16.19%, 17.08%, 3.81%, 5.66%, and 5.34%, respectively. Pb content in zone 1 tea samples marginally exceeded the permissible limit of 10mg/kg specified by the Prevention of Food Adulteration Act. The analysis revealed that PTE contamination in tea leaves followed a decreasing order of contamination: zone 1 > zone 2 > zone 3 > zone 4. Self-organizing map revealed an inverse relationship among pH, organic carbon content, and bioavailable forms of PTEs. Sobol sensitivity analysis identifies a strong influence of leaf infusion particularly on the gastric phase of humans and the Random Forest algorithm emerged as the best-performing model in the Taylor Diagram. The FIAM-based hazard quotient (HQ) was above 0.5 for Cr, Ni, and Pb indicating a potential risk for the consumers. However, carcinogenic risk assessed via the Severity Adjustment Margin of Exposure (SAMOE) model was negligible. This report could be useful for establishing tolerance limits for toxic elements to mitigate the health hazards associated with tea consumption.