Bhutan Journal of Natural Resources and Development

Diversity and Distribution of Ladybird Beetles (Coleoptera: Coccinellidae) under Different Habitats in Zhemgang, Bhutan

Jigme Wangchuk, Wangchuk Blon, Dorji Phuntsho, Karma Tenzin, Cheten Dorji — Mon, 30 Dec 2024 00:00:00 +0000

The diversity of ladybird beetles is of great importance due to their worldwide utilization as biological control and indicator. The present study was conducted to evaluate the diversity and distribution of ladybird beetles in three different habitats and regions of Nangkor Gewog under Zhemgang district. The stratified line transect sampling technique was employed for the collection of specimens using sweep net and beating tray. A total of 13 species under three tribes with 402 individuals were recorded. Widely found and used biological control species, Coccinella septempunctata was the most abundant species found in the study area with its relative abundance of 34.33% when compared to other species. Overall rank distribution based on relative abundance showed that 15 species distributed within 14 ranks. The study area had an overall diversity, H′ = 2.04, D_mg = 2.33 and J = 0.75. A series of diversity comparisons across different regions within the study area, including habitats and habits showed variable species diversity and host plant preferences. As anticipated, the forest area harboured the most diverse ladybird beetle species, with Brassica juncea being the most favoured plant, hosting 84 individuals. The present study offers insights into the ladybird beetle diversity, that enhance our understanding and potential future use of these insects as a biological control.

Whole-mount Bone Staining of Selected Cyprinidae Fishes of Punatsangchu, Bhutan

Yeshi Phuntsho, Karma Wangchuk, D.B.Gurung — Mon, 30 Dec 2024 00:00:00 +0000

Whole-mount bone staining was used to study skeletal system and reproductive toxicology for a long time. Alizarin red S and Alcian blue were used for a decade to stain specimens, and it is still widely used today. The study was conducted to standardize the rapid whole-mount bone staining protocol for larger specimens of selected cyprinidae and to compare meristic and morphometric data before and after staining, which further generates comparative information on the osteological characteristics of the fishes found in Punatsangchu River. The specimens were collected using purposive sampling and stored in 10% formalin. The protocol of the whole-mount bone staining method was modified by changing the concentration of reagent and the timing required based on the size of the specimens. Formalin, Triton X-100, and potassium hydroxide were used as fixative solutions. The enhancement solution consisted of ethylene glycol, Triton X-100, and potassium hydroxide. Alizarin red S and ethylene glycol were used as the bone staining solution and Alcian blue as the cartilage staining solution. Tween 20 and potassium hydroxide were used as clearing solutions. Details of the meristic counts were compared following both pre- and post-staining procedures. In all four species, the meristic counts revealed significant differences (p= .03, N=20). However, comparative morphometric measurements revealed no significant difference between and within species (p=1.00). The strong stout spines on the dorsal and anal fins remained the same, indicating that bone staining was useful in species identification.

Ethnomedicinal Uses and Phytochemical Concentration of Bergenia ciliata (Haw.) Sternb. from Three Districts in Bhutan

Ashika Rai, Tulsi Gurung, Bhagat Suberi — Mon, 30 Dec 2024 00:00:00 +0000

Bergenia ciliata (Haw.) Sternb., which is commonly known as elephant ears, is a perennial herb in the Saxifragaceae family. It is traditionally used in ethnomedicine to treat kidney stones, lung disorders, and gastrointestinal illnesses due to its rich secondary metabolites. This study documented twelve medicinal uses of B. ciliata through semi-structured interviews of 67 informants, using a snowball sampling technique across three study sites. Phytochemical analysis showed a significant difference (p ≤ 0.001) in tannic, phenolic, and flavonoid content across the study sites. Tannin content was highest in samples collected from Chapcha (0.77 ± 0.08 µg/ml), phenolic from Chendebji (2.85 ± 0.19 µg/ml), and flavonoid from Patshaling (340 ± 94.82 µg/ml). There were no significant differences in the concentrations of catechin, gallic acid, and bergenin. The highest catechin content was found in samples from Chendebji (29.85 ± 4.09 %), the gallic acid concentration was highest from Patshaling (17.67 ± 7.88 %), and Chapcha samples showed the highest bergenin concentration (196.0 ± 19.63 mg/kg). In general, the concentration of most of the phytochemicals was found lower than from other studies in the region which could be due to the differences in the extraction method, stage of maturity of the rhizomes, and the harvesting time apart from the environmental impact. This study suggests that further research on the phytochemical analysis of Bergenia is necessary, as it has not been previously explored in Bhutan. Additionally, documenting its uses from other regions of Bhutan is equally important.

Macroinvertebrates Diversity and Seasonal Dynamics in the Streams of Southwest Bhutan: Preliminary Findings and Implications for Future Research

Kinzang Dorji — Mon, 30 Dec 2024 00:00:00 +0000

Traditionally, assessing stream and river health in the Hindu Kush-Himalayan (HKH) region has relied primarily on physical and chemical data, which offer limited insights into aquatic ecosystems. The recent Assessment System to Evaluate the Ecological Status of Rivers in the Hindu Kush-Himalayan region (ASSESS-HKH) project marks a significant advancement by developing robust bio-assessment tools. This initiative was crucial for addressing the region’s unique ecological challenges, characterized by its rich biodiversity and essential freshwater resources. In Bhutan, however, the use of macroinvertebrates as bioindicators for water quality assessment has been limited. This study aimed to enhance stream health evaluation in southwest Bhutan by utilizing macroinvertebrates. Two representative streams were sampled using detailed techniques, revealing a diverse range of macroinvertebrate families - 39 families in one stream and 34 in the other - with notable variations in abundance among key taxa. Seasonal changes in community composition reflected ecological dynamics influenced by factors such as water temperature, flow regime, and substrate composition. HKH biotic scores indicated minimal stream impairment. The study highlights the need for sustainable monitoring and management of stream health in southwest Bhutan. Future research should investigate the effects of monsoonal patterns on macroinvertebrate diversity, conduct long-term monitoring, and assess the impact of anthropogenic activities to further refine conservation strategies.

Citrus Culture in Bhutan

Choki Dorji, Dophala, Dorji Phuntsho — Mon, 30 Dec 2024 00:00:00 +0000

Mandarin orange production and trade data were analyzed using semi-logarithmic trend analysis to evaluate growth rates and trends in mandarin orange production and trade. Results indicated a positive trend in mandarin orange production and yield, reflecting the resilience and adaptability of Bhutanese farmers despite challenges such as the Citrus tristeza virus (CTV) and Candidatus Liberibacter asiaticus (CLas). However, a declining trend in harvested areas raises concerns about constraints such as diseases or shifting agricultural priorities. Import trends revealed a growing demand for citrus products domestically, necessitating efforts to enhance domestic production capacity. While export values demonstrate growth, stagnant export quantities underscore the need to boost production, quality, and market positioning. Overall, the citrus industry in Bhutan demonstrates modest growth potential, but strategic interventions such as micro-budding and high-density planting are essential to address the challenges and unlock its full economic potential. This study provides valuable insights for policymakers and stakeholders to formulate targeted interventions in sustaining and enhancing the citrus sector’s contribution to economy.

Screening of Beans (Phaseolus vulgaris L.) Genotypes for Drought Tolerance

Jigme Thinley, Tulsi Gurung — Mon, 30 Dec 2024 00:00:00 +0000

Drought is a critical factor that limits crop yield and contributes to global food insecurity. In regions where beans are cultivated, 60% of the crop is vulnerable to drought, resulting in an 80% reduction in yield. This presents a growing threat to farming communities in Bhutan, where limited research on crop drought tolerance has been conducted. To address this issue, a study was undertaken to evaluate the drought tolerance of six bean genotypes: Orey serbu, Orey regtang, Orey brokchilu, Yadhipa orey, Kerongree orey, and Brokopali. The study employed a Completely Randomized Design (CRD) consisting of six treatments each with three replications. The genotypes were subjected to drought stress after 50% flowering until the onset of pod formation, with drought conditions maintained for 10 days during pod formation, followed by restored irrigation until harvest. Key parameters such as leaf area, root weight, shoot weight, as well as yield metrics including the number of pods and seed weight, were assessed at harvest. The findings indicated significant differences (p<.05) in all parameters measured under stressed versus non-stressed conditions. Water stress was found to adversely affect the growth and development of all bean genotypes. With performance as regards to Drought Susceptibility Index (DSI) which is a measure of yield stability (DSI = (1- Yd / Yw) / D. Brokpali, Yadhipa orey, and Orey serbu demonstrated the lowest values for the drought susceptibility index (DSI), suggesting a greater level of tolerance to drought for these specific genotypes.

Effects of Fagopyrum esculentum (Buckwheat) and Vigna radiata (Mung Bean) Cover Crops (Monoculture and Mixture) on Soil Organic Matter, Total Nitrogen, and Available Phosphorus

Tenzin Wangchuk, Pema Tamang — Mon, 30 Dec 2024 00:00:00 +0000

Cover crops play a vital role in enhancing soil health and agroecosystem sustainability. This study evaluated the effects of monoculture and mixed cover crops on soil nutrient dynamics under dry subtropical conditions in Bhutan. The experiment followed a randomized complete block design with four treatments: buckwheat (Fagopyrum esculentum) monoculture, mung bean (Vigna radiata) monoculture, buckwheat-mung bean mixture, and control (no cover crops). The biomass of the cover crops was sampled destructively 45 days after sowing and then incorporated into the soil. Five composite soil samples were collected at intervals of 15 days to determine the changes in soil nutrients after the incorporation of cover crop residue. By 60 days after residue incorporation, soil organic matter levels were significantly higher in the mung bean (7.64 ± 0.66%) and mixture plots (6.85 ± 0.62%) compared to the control plots (5.41 ± 0.28%). Total nitrogen was also significantly higher in the mung bean (0.38 ± 0.03%), and mixture plots (0.34 ± 0.03%), compared to the control plots (0.27 ± 0.01%). Buckwheat (monoculture) consistently enhanced available phosphorus levels (0.23 ± 0.01 ppm), followed by the mixture (0.14 ± 0.01 ppm), both significantly higher than mung bean (0.06 ± 0.01 ppm) and the control plots (0.09 ± 0.01 ppm). These findings emphasize the potential use of buckwheat and mung bean as cover crop mixtures to enhance soil health through complementary nutrient contributions. This study provides valuable insights for promoting cover cropping practices to address soil fertility challenges in Bhutan.

Environmental DNA (eDNA) as a Tool for Freshwater Fish Biodiversity Monitoring in Bhutan: A Review

Ugyen Dorji — Mon, 30 Dec 2024 00:00:00 +0000

Bhutan’s freshwater ecosystems are home to diverse and unique fish species, many of which are under threat from hydropower development, urbanization, and invasive species. Traditional fish biodiversity monitoring methods, such as net sampling and electrofishing, are limited by logistical challenges, species detection biases, and resource constraints, particularly in Bhutan’s rugged and remote landscapes. Environmental DNA (eDNA) offers a promising solution by enabling non-invasive, cost-effective, and highly sensitive species detection through the analysis of genetic material in environmental samples. This review explores the potential of eDNA to revolutionize fish biodiversity monitoring in Bhutan, highlighting its advantages in detecting cryptic and rare species, informing conservation efforts, and supporting long-term ecosystem monitoring. The challenges of implementing eDNA in Bhutan, such as the need for infrastructure, skilled personnel, and funding, are discussed, along with potential future applications for ecosystem management and invasive species control. By investing in eDNA technology, Bhutan can enhance its biodiversity conservation strategies, contributing to the global understanding of freshwater ecosystems in biodiversity hotspots.