Department of Zoology

Permanent URI for this collectionhttps://ir.nbu.ac.in/handle/123456789/184

Browse

Filters

2021 - 20238

Advanced Search

Filter by

Settings

Start date: 2020End date: 2023

Search Results

Now showing 1 - 8 of 8
  • Thumbnail Image
    ItemOpen Access
    A study on the defence system of the tea pest hyposidra talaca (Walker, 1860) (Lepidoptera : Geometridae) against chemical pesticides and entomopathogens
    (University of North Bengal, 2023) Ghosh, Saugata; Bahadur, Min
    Introduction: Tea, Camellia sinensis (L.) O. Kuntze, is an economic perennial monoculture crop in the sub-Himalayan region of West Bengal. This foliage crop is regularly infested by a large number of insect species. Of these, looper stage of black inch worm, Hyposidra talaca (Walker) (Lepidoptera: Geometridae), causes substantial crop loss in the Darjeeling Terai tea plantations and has emerged as a dominant tea pest in this region. The effective, eco-friendly pest management strategies against Hyposidra talaca demands the insight knowledge of the defense mechanisms of this lepidopteran pest against the chemical pesticides that are indiscriminately used in this region, as well as, against the entomopathogenic groups of organisms including viruses, fungi, bacteria, microsporidia, protists and nematodes, to provide a non-chemical alternative for insect pest management. Background: Insect defense system against chemical pesticides as well as entomopathogens comprises cellular or haemocyte-associated molecules, humoral plasma borne factors and the defense enzyme systems. Cellular immune responses, including phagocytosis, nodulation and encapsulation are mediated by haemocytes against any type of foreign agents that enter hemocoel. The success of the cellular defense depends on the number and types of haemocytes involved in these processes. Melanin synthesis and antimicrobial peptide (AMP) production are two arms of humoral defense system. Melanization is caused by the activity of phenoloxidase (PO) as a response to infection or wounding. Melanin is deposited within nodules, composed of aggregated haemocytes and microorganisms that form in the heavily infected insects. AMPs are pattern-recognition molecules that recognize microbial cell wall components, called pathogen associated molecular patterns (PAMPs). The phytophagous pest can tolerate the toxic substances present in the host plant as well as the chemical pesticides through production of defense (detoxification) enzymes. Generally, three enzyme systems, general esterases, cytochrome P450-dependent monooxygenases and glutathione S-transferases are known to be involved in the detoxification of allelochemicals as well as insecticides. Materials and methods: Considering the above facts, in this study the cellular immune system of Hyposidra talaca has been investigated by characterizing the haemocytes and determining the total and differential count of haemocytes in different ages of last two instars of naïve larvae, in different food regimes (natural and artificial diets) as well as under the challenge of two selected chemical pesticides, emamectin benzoate, cypermethrin and the entomopathogens, a nucleopolyhedrovirus and Bacillus thuringiensis infecting H. talaca. The activities of three defense enzymes, viz. general esterases, cytochrome P450 and glutathione s-transferase, have been determined under the challenge of two chemical pesticides, viz. emamectin benzoate and cypermethrin. The humoral defense system has been studied by gel electrophoresis of the cell free haemolymph taken from Bacillus thuringiensis-infected larvae of Hyposidra talaca. Results: Haemocyte count in respect to developmental ages and food regimes: In the life history of H. talaca five larval instars were recorded. From the haemolymph of 5th instar larvae, five types of haemocytes viz. prohaemocyte (PR), plasmatocyte (PL), granulocyte (GR), spherulocyte (SP) and oenocytoid (OE) have been identified by light microscopic study. Irrespective of diet, total haemocyte count (THC) showed gradual increase along the development of last two instars with transient decrease just after ecdysis and finally declined steeply during the wandering and the pre-pupal stage in the last larval instar. However, the artificial diet (AD)-reared larvae showed higher haemocyte count in comparison to the larvae of the same age group, reared on natural diet. The proportion of the major haemocyte types, PLs, GRs and SPs showed fluctuation along the larval development with higher proportion of PLs and GRs (only immunoreactive haemocytes) in the haemolymph of the AD-reared larvae. Haemocyte count in respect to the exposure of chemical pesticides and entomopathogens: A general reduction in THC was observed in the larvae exposed to sub-lethal concentrations of pesticides and entomopathogens used in this study; only a transient initial increase was recorded after 24 hrs exposure to NPV. The differential count of haemocytes (DHC) showed an increase in the proportions of the PLs with a corresponding decrease of GRs in response to the treatment of the chemical pesticides and NPV, however, an opposite trend was recorded for GRs in Bt-infected larvae at 24 and 48 hrs post-infection. Effects of the chemical pesticides on the activities of detoxifying enzymes: The activities of general esterases (GEs), cytochrome P450 (CYPs) and glutathione S-transferase (GST) in the larvae of H. Talaca were recorded to be changed in response to the treatment with the sub-lethal concentrations of emamectin benzoate and cypermethrin. GE activity decreased in comparison to control when exposed to pesticides, whereas the CYP activity increased after 24 hrs of exposure of pesticides but decreased only after long time exposure (72 hrs) which is just opposite to the effect of pesticides observed in GST. Electrophoretic analysis of haemolymph proteins/peptides in relation to the microbial exposure: The SDS-PAGE analysis of cell free haemolymph of H. talaca larvae infected with sub-lethal concentration of Bt-based biopesticides revealed different proteins of varying molecular weights. The relative abundance of these proteins was found to vary in the infected larvae compared to the control. Hypoproteinemia of 65-77 kDa proteins (presumed to be storage proteins), after 24 hrs of post-infection and hyperproteinemia of 30 kDa protein (presumed to be 30K protein) and 18 kDa protein (presumed to be apolipophorin III) after 48 and 72 hrs of post-infection along with a general over expression of some low molecular weight proteins/peptides (11-13 kDa) have been detected in the infected larvae. Conclusion: The results of this study showed the induction of cellular, humoral and metabolic defense of Hyposidra talaca larvae in response to chemical pesticides, emamectin benzoate and cypermethrin as well as entomopathogens, nucleopolyhedrovirus and Bacillus thuringiensis.
  • Thumbnail Image
    ItemOpen Access
    Studies on microbial diversity of some fish products of North Bengal
    (University of North Bengal, 2022) Yonle, Rujas; Pal, Joydeb
    Fish is an important source of nutrition in many people's diets around the world. Fish and fish products are regularly consumed by people of various ethnicities in North Bengal. The current study examines the various types of fish consumed in North Bengal. During the survey, three types of locally prepared fish products were documented: Loah ko Dalla, Sidol, and Jhinghe Maacha. Among the three fish products, Loah ko Dalla was primarily consumed in parts of the Darjeeling and Kalimpong districts of North Bengal, particularly in villages along the river Rangeet, Balasan and Relli. Only the Rajbanshi tribes of North Bengal plains were found to consume the product Sidol. Jhinghe Maacha, on the other hand, was a popular fish product consumed widely throughout North Bengal. The fish products Loah ko Dalla and Sidol were rarely sold in the open market and were only produced for domestic consumption, whereas Jhinghe Maacha was readily available in all of North Bengal's fish markets. Four Loah ko Dalla sample batches, three Sidol sample batches, and four Jhinghe Maacha sample batches were collected from various parts of North Bengal. A total of 219 isolates of microorganisms were isolated from the eleven samples. All of the samples collected were found to have a 100% prevalence of LAB (Lactic acid Bacteria). All of the fish products had a microbial load of LAB ranging from 103 to 105 cfu/g. From the 148 LAB strains isolated from all of the fish products, 113 were cocci and were identified as Lactococcus plantarum, Leuconostoc mesenteroides, Pediococcus pentosaceus, Enterococcus faecium, and Enterococcus faecalis, while the remaining 35 were non-spore forming rods and were identified as Lactobacillus fructosus and Lactobacillus plantarum. A total of 62 spore former strains were isolated from the 11 samples of fish products collected, out of which 42 strains were endospore forming rods and 20 strains were aerobic cocci. The prevalence of endospore forming rods in all the fish samples were 91 % and aerobic cocci 64%. The microbial load of the spore formers was found to be< 103 cfu/gm with values ranging from 101 to 104 cfu/g. The isolated strains of endospore forming rods were identified as Bacillus subtilis and Bacillus pumilus. The isolated 20 strains of aerobic cocci were all identified as Micrococcus sp. The Micrococcus had a prevalence of 64% in all the samples analysed. The microbial load of yeast in all the samples were found to be <1 cfu/g and no mould could be ascertained from all the products analysed. All 9 strains of yeast were isolated from only Loah ko Dalla and were identified as Candida sp. The prevalence of the yeast in all the samples was found to be 27%. The total viable count of the 11 samples was found between 103 to 105 cfu/g. The major food pathogens Bacillus cereus, Staphylococcus aureus and Enterobacteriaceae were isolated from all the fish products. Bacillus cereus has a prevalence of 73 % in all the fish products analysed with microbial load ranging between 102 to 103 cfu/ g. Staphylococcus aureus was also isolated from all the fish samples with a prevalence of 64% and microbial load ranging between 102 to 103 cfu/g. Enterobacteriaceae was also isolated from all the fish samples with a prevalence of 82% and microbial load of 103 cfu/g in all the fish samples. The proximate analysis of all the fish samples revealed the pH of 6 to7 in all the samples with no detectable acidity. Sida! had the highest moisture content of 50%, and Jhinghe maacha had the highest ash content of 82.44 %. The protein content was highest in Jhinghe Maacha and lowest inLoah ko Dalla with 54.55% and 9.27% respectively. The fat content was highest with 50% in Loah ko Dalla and lowest in Sida! with 21. 7 5%. All fish samples were tested for mineral content, specifically calcium, iron, magnesium, manganese, and zinc. The calcium content in Loah ko dalla, Sida!, and Jhinghe maacha was 38.42 mg/lO00g, 50.24 mg/lO00g, and 129.65 mg/lO00g, respectively. The iron content in Loah ko dalla, Sida!, and Jhinghe maacha was 56.51 mg/lO00g, 41.28 mg/lO00g, and 35.50 mg/1 000g, respectively. The magnesium content in Loah ko dalla, Sida!, and Jhinghe maacha was 77.25 mg/l000g, 129.63 mg/l000g, and 137.95 mg/l000g, respectively. Manganese content in Loah ko dalla was 2.41 mg/lO00g, Sidol 3.99 mg/lO00g, and Jhinghe maacha 1.2 mg/1 000g. The zinc content in Loah ko dalla was 4.13 mg/1 000g, Sidol 8.25 mg/lO00g, and Jhinghe Maacha 3.60 mg/l000g. The findings of the research indicate the presence of LAB, spore formers, and yeast in all of the fish products. Although none of the pathogens exceeded the hazard limit, the presence of pathogenic bacteria Bacillus cereus, Staphylococcus aureus, and Enterobacteriaceae in the entire fish sample indicates poor handling and preservation practices. The research finding also indicates the fish products contain substantial amount of food value in terms of protein, fat and nutrient content.
  • Thumbnail Image
    ItemOpen Access
    Limnochemistry, diversity of plankton and ichthyofauna of some rivers of the Dooars region, West Bengal
    (University of North Bengal, 2022) Sarkar Tapan; Pal Joydeb
    The present study, entitled “Limnochemistry, diversity of plankton and ichthyofauna of some rivers of the Dooars region, West Bengal”, was conducted for a period of two years from March 2014 to February 2016. Three rivers, such as the Teesta, Jaldhaka, and Torsa, and two sites for each river, were selected for study. The study was conducted in three sections, such as physico-chemical parameters of river water, plankton diversity, and ichthyofaunal diversity. Temperature, pH, TS, TDS, TSS, DO, free CO2, chloride, TA, and TH were determined by standard methods. The Pearson’s correlation coefficient matrix, two-way ANOVA among seasons and sites, and one-way ANOVA between the two years were calculated using SPSS 16.0 and PAST 3.0 software. PCA was done by PAST 3.0 software. The air temperature, water temperature, depth of water, pH, dissolved oxygen, electrical conductivity, total dissolved solid, total suspended solid, total solid, total alkalinity, total hardness and chloride showed seasonal variation in the three investigated rivers. The water temperature, pH, TDS, TSS, TS, total alkalinity, total hardness, and chloride did not show any significant differences among the six sites of the three investigated rivers, but the depth of water, DO, and FC showed significant differences among the six sites. Water temperature is the most important parameter that controls other physico-chemical parameters of water. The pH, electrical conductivity, DO, TA, and TH of the three investigated rivers are within the optimum range, making them suitable for fish and other organisms. The DO and FC of the three investigated rivers indicate the good quality of water. Total alkalinity and total hardness indicate that the water of the three investigated rivers is soft in nature. The PCA concentrates variances of the original data of physico-chemical parameters into two principal components (PC1 and PC2) in the case of rivers Jaldhaka and Torsa and three principal components (PC1, PC2 and PC3) in the case of the river Teesta. PC1 represents more physical and less chemical, while PC2 represents more chemical and less physical. WT, TDS, TH, and TA are the most influential factors. A total of 24, 26, and 25 genera of phytoplankton belonging to five groups were recorded during the study period from the rivers Teesta, Jaldhaka, and Torsa, respectively. A total of 28 genera of phytoplankton were recorded from the three investigated rivers. Chlorophyceae was the most dominant group in all the three rivers. Phytoplankton density, numbers of phytoplankton genera, Shannon-Wiener diversity index, and Margalef’s species richness index are positively correlated with pH, TDS, conductivity, dissolved oxygen, total alkalinity, total hardness, and chloride but negatively correlated with air temperature, water temperature, depth of water, TSS, and free CO2. Similar relations have been suggested by PCA. A total of 17, 16, and 16 genera of zooplankton were obtained from the rivers Teesta, Jaldhaka, and Torsa, made up of protozoa, rotifera, cladocera, and copepoda. A total of 18 genera of zooplankton were recorded from the three investigated rivers. The density, number of genera, Shanon diversity index, and Margalef’s richness index of phytoplankton and zooplankton also showed seasonal variation in the three investigated rivers. The density and number of phytoplankton and zooplankton genera, Shannon-Wiener diversity index, and Margalef’s species richness index are positively correlated with pH, TDS, conductivity, dissolved oxygen, total alkalinity, total hardness, and chloride but inversely correlated with air temperature, water temperature, depth of water, TSS, free CO2. Similar relations have been suggested by PCA. The density, number of genera, diversity index, and Margalef’s species richness index of phytoplankton and zooplankton are positively influenced by PC2, meaning affected by the chemical properties of water such as DO, TDS, TA, TH, and CL. The number of genera, diversity index, and Margalef’s species richness index of phytoplankton and zooplankton are negatively influenced by PC1. They are also negatively affected by the physical properties of water such as water temperature, TSS, TS, and free carbon dioxide. PCA biplots confirmed that phytoplankton and zooplankton density and/or number were the most influential factors which influenced the diversity indices. A total of 147 fish species of ichthyoauna with remarkable variations in Teesta (140 species), Jaldhaka (119 species) and Torsa (131 species) were recorded. A total of 147 species belonging to 11 orders and 31 families were recorded over the study period from the three rivers. Out of 147 recorded species, 1 is Critically Endangered (0.68%), 20 (13.60%) are Endangered (EN) and 42 (28.57%) are Vulnerable (VU) (according to CAMP-NBFGR). But according to IUCN conservation status, 2 (1.36%) species are Endangered (EN) and 1 (0.68%) species is Vulnerable (VU). Out of 147 recorded species, 1 (0.68%) is Critically Endangered, 12 (8.16%) species are Endangered (EN), 23 (15.6%) species are Vulnerable (VU) and 33 (22.45%) species are near threatened (NT) (according to Barman). Of the total of fish species, only 10.20% (15 species) are endemic fish species recorded from the three rivers. Two endemic fish species are found only in North Bengal. CPUE, number of ichthyofauna genera, Shanon diversity index, and Margalef’s species richness index of ichthyofauna showed seasonal variation in the three investigated rivers. CPUE, density, Shannon-Wiener diversity index, and Margalef’s species richness index exhibited significant and positive correlation with air temperature, water temperature, depth of water, TSS, TS, and free carbon dioxide but a significant and negative correlation with TDS, dissolved oxygen, conductivity, total alkalinity, total hardness, and chloride. Similar relations have been suggested by PCA. CPUE, NF, and DVF are influenced by PC1, meaning more physical parameters such as water temperature and depth of water, but negatively influenced by DO, TDS, TA, TH, and CL. PCA biplots revealed that CPUE and the number of fish genera were the most influential factors that influenced diversity indices. Use of fine mesh size nets for fishing; river bed as an agricultural field; disposal of municipal waste; river embankment; presence of invasive fish species; mining of sand, gravel, and boulders from riverbed flood etc. are all threats to fish diversity.
  • Thumbnail Image
    ItemOpen Access
  • Thumbnail Image
    ItemOpen Access
    Detection of human polyomavirus JC (JCV) and its genotyping in immunocompromised and non-immunocompromised individuals from sub-Himalayan West Bengal
    (University of North Bengal, 2021) Chattaraj, Sutanuka; Bhattacharjee, Soumen; Bera, Nirmal Kumar
  • Thumbnail Image
    ItemOpen Access
    Exploration of Anti-inflammatory and Anti-arthritic propertics of Aloe Vera (L.) Burm. f. from the Sub-Himalayan West Bengal, India
    (University of North Bengal, 2021) Paul, Subhashis; Bhattacharjee, Soumen; Chaudhuri, Tapas Kumar
  • Thumbnail Image
    ItemOpen Access
  • Thumbnail Image
    ItemOpen Access