Department of Zoology

Morphometric and Molecular Characterization of Mosquito Species from Different Larval Habitats in Gulshan Thana, Dhaka

2026-03-02T00:00:00Z

Morphometric and Molecular Characterization of Mosquito Species from Different Larval Habitats in Gulshan Thana, Dhaka Noor-E Jannat, Khandaker This comprehensive study, conducted in Gulshan Thana, Dhaka, investigated mosquito diversity, larval habitat characteristics, and cryptic species identification using an integrated approach combining wing morphometrics and molecular analysis. Larval habitats were systematically surveyed across natural and artificial breeding sites during pre-, peak-, and post-monsoon seasons over three consecutive years using a stratified random sampling design. GPS-referenced data analyzed in ArcGIS Pro revealed high-density breeding zones through kernel density and hotspot analyses. A total of 36 mosquito species across eight genera were identified, including 11 new records for Bangladesh: Aedes (Ae.) aegypti aegypti, Ae. aegypti var. luciensis, Ae. flavopictus, Culex (Cx.) annulirostris, Cx. pipiens, Cx. pipiens f. pipiens, Cx. pipiens f. molestus, Cx. pipiens pallens, Cx. pseudosinensis, Lutzia (Lt.) chiangmaiensis, and Ochlerotatus sp. The Breteau Index comparison between Ae. aegypti and Ae. albopictus was significant (U = 109.5, p = 0.032), peaking in September, with Korail slum identified as a year-round hotspot for Ae. aegypti. Habitat preferences varied, with Culex preferring drains (16.83%) and Aedes favoring water filter pots (27.07%). Morphometric analysis of wing landmarks (CVA and PCA) revealed significant interspecific variations in size and shape (p < 0.0001). Molecular characterization using COI and rRNA markers produced 33 COI and four ribosomal sequences, with an average length of 662.91 base pair. Genetic divergence among six mosquito genera was evaluated using the Kimura 2-parameter model, revealing an average pairwise distance of 21.62%. A Neighbor-Joining (NJ) tree was constructed with 1,000 bootstrap replicates using MEGA 11, to evaluate the robustness of the inferred clades. The Kruskal-Wallis test confirmed significant intergeneric variation (H = 33.14, p = 3.54 × 10⁻⁶). A median-joining network of 20 COI haplotypes revealed high intraspecific genetic diversity (HD = 1.000 ± 0.016; π = 0.11723 ± 0.00855). Notably, Ae. aegypti showed clear divergence from its cryptic subspecies: Ae. aegypti aegypti (distance: 0.21) and Ae. aegypti var. luciensis (distance: 2.15), with 2.30% divergence. The detection of geographically isolated taxa such as Cx. pipiens pallens and Ae. aegypti var. luciensis highlights ongoing ecological range expansion among invasive disease vectors. This thesis is submitted for the degree of Doctor of Philosophy.

Impact of knowledge, attitude and practice on rural women and children with soil-transmitted helminths infections in Rangpur

2025-10-06T00:00:00Z

Impact of knowledge, attitude and practice on rural women and children with soil-transmitted helminths infections in Rangpur Liza, Fahmida Tasnim A cross-sectional descriptive study was conducted on soil-transmitted helminths (STHs) among school-age children (ages 6–12 years) and rural women (ages 15–49 years) from the Bengali and Santal communities in Rangpur, Bangladesh. A total of 352 women responded to the questionnaire on knowledge, attitude, and practice (KAP) related to STH infections. Socio demographic data reveals differences in religion, marital status, income, education, profession, and toilet facilities between the Bengali and Santal populations. Income, education, occupation, and the type of toilet user with STH infections correlate significantly with KAP (p < 0.05). Out of the 234 stool samples that were collected and examined, 81.9% and 100% of the samples from women (N = 188) and children (N = 46), respectively, were determined to be infected. A. lumbricoides was the most common STH (78.72% and 78.26%), whereas T. trichiura was the least prevalent parasite (3.19% and 4.3%) in both groups respectively. Women with low or no knowledge of the importance of eating well-cooked food, maintaining good hygiene, and receiving basic health education were shown to be substantially more likely to have high rates of STHs (p < 0.05). In this study, two categories — nail trimming and use of anthelmintic drugs by women from both populations were found to be positively associated with STH infections (p < 0.05). There was no discernible correlation (p > 0.05) between the prevalence of STHs and physical conditions such as diabetes, body mass index (BMI), COVID-19, and upset stomach. Interventions like deploying health extension workers, upgrading hygienic facilities, and promoting improved personal hygiene should be considered throughout the community. The results indicate the need for health education and improvement in community socioeconomic status. This thesis is submitted for the degree of Master of Philosophy.

Genetic Diversity, Phylogenetic Relationship and Status of Shrimps (Crustacea:Decapoda) of Bangladesh

2025-11-05T00:00:00Z

Genetic Diversity, Phylogenetic Relationship and Status of Shrimps (Crustacea:Decapoda) of Bangladesh Datta, Sujan Kumar Shrimp, a popular and delicious food item worldwide, holds significant commercial and food value, providing a vital source of protein and contributing to a multi-billion-dollar industry in both wild-caught and farmed varieties. Belonging to the order Decapoda, shrimp play a vital role in both marine and freshwater ecosystems. However, a comprehensive, systematic taxonomic study, especially in molecular taxonomy, has not been conducted for these species in Bangladesh. To address this gap, the present study aimed to explore the genetic diversity, phylogenetic relationships, and status of shrimp species found in Bangladesh. An integrative taxonomic approach was used, combining morphological examination, DNA barcoding, and molecular species delimitation to provide a broad understanding of the systematics of shrimps in the region. Specimens were initially identified morphologically, followed by molecular analysis using two genetic markers: the mitochondrial cytochrome c oxidase I (COI) gene and the 16S ribosomal RNA (16S rRNA) gene. 50 shrimp species, representing six families and 16 genera, were morphologically identified, and 38 species and two genera were further confirmed through molecular analysis. A total of 127 sequences were generated, comprising of 55 COI and 72 16S rRNA sequences. Sequence analysis revealed 136 conserved, 561 variable, and 321 parsimony-informative sites for the COI gene, and 101 conserved, 583 variable, and 372 parsimony-informative sites for the 16S rRNA gene. The average GC content was 40.87% for COI and 33.49% for 16S rRNA. Genetic divergence was assessed with mean distances of 1.18 ± 0.02%, 23.53 ± 0.08%, and 28.29 ± 0.05% within species, genus, and family for the COI gene. For the 16S rRNA gene, the corresponding values were 2.94 ± 0.09%, 13.91 ± 0.06%, and 25.26 ± 0.04%. Notably, the mean interspecific genetic distance for COI was 34 times greater than the intraspecific distance, while for 16S rRNA, it was 15 times greater, with barcode gaps of 38.54% and 40.91% for the two markers, respectively. Phylogenetic trees based on the Neighbor-Joining (NJ) method were generated for each gene marker to explore the phylogenetic relationships among the identified species. Additionally, 11 species were newly recorded from Bangladesh, marking their first geographic occurrence in the region. This is the first comprehensive study combining morpho-taxonomy, molecular analysis, and phylogenetic relationships of shrimps from Bangladesh. The study underscores the need for effective conservation strategies and sustainable management practices to preserve the rich shrimp diversity in Bangladesh, as revealed by the molecular and phylogenetic findings. The results not only enhance our understanding of shrimp biodiversity in Bangladesh but also lay a foundation for future research on the ecological and evolutionary dynamics of these crucial aquatic organisms. This thesis is submitted for the degree of Doctor of Philosophy.

Trichodinid ciliates (Ciliophora: Trichodinidae) of selected freshwater fishes of Hakaluki Haor, Bangladesh

2025-11-05T00:00:00Z

Trichodinid ciliates (Ciliophora: Trichodinidae) of selected freshwater fishes of Hakaluki Haor, Bangladesh Ahasan Habib, Md. Moin Uddin This dissertation presents a comprehensive study on the occurrence of trichodinid ciliates parasitizing freshwater fishes from Hakaluki Haor, Sylhet, Bangladesh, conducted between April 2018 and March 2022. A total of 44 host fish species, belonging to 8 orders, 18 families, and 32 genera, were examined; among them, 16 species were infested with trichodinid ciliates. Altogether, 29 species of trichodinid ciliates were identified belonging to three genera: Trichodina Ehrenberg, 1830; Trichodinella (Raabe, 1950) Šrámek-Hušek, 1953; and Tripartiella Lom, 1959. Twenty-four species of Trichodina were identified, of which 22 are redescribed, viz., T. acuta, T. ahmedi, T. anabasi, T. cancilae, T. caspialosae, T. cobitis, T. cubanensis, T. domerguei, T. glossogobae, T. gulshae, T. hafizuddini, T. heterodentata, T. hoffmani, T. japonica, T. kupermani, T. modesta, T. molae, T. nigra, T. notopterusi, T. ovonucleata, T. siluri and T. sylhetensis. Two species of Trichodina are described and new to science, viz., Trichodina sp. 1 n. sp. and sp. 2 n. sp. Two species of Trichodinella, viz., Trichodinella epizootica and Trichodinella sunderbanensis, were recorded, along with three species of Tripartiella, viz., Tripartiella bulbosa, Tripartiella copiosa, and Tripartiella obtusa. Among the 29 species, eight (T. ahmedi, T. cubanensis, T. caspialosae, T. glossogobae, T. kupermani, T. notopterusi, T. ovonucleata, and Trichodinella sunderbanensis) are recorded for the first time from Bangladesh. Taxonomic identification followed the protocols of Lom (1958), Wellborn (1967), Arthur and Lom (1984), and Van As and Basson (1989, 1992). All species descriptions were based on dry silver nitrate impregnated specimens following Klein (1958). Photomicrographs captured at 1000× magnification, detailed morphometric data for each trichodinid species, and diagrammatic illustrations of denticles for selected taxa are included. Observations on host specificity, distribution patterns, and seasonal incidence of infection contribute valuable insights into the diversity and ecology of trichodinid ciliates in freshwater ecosystems of Hakaluki Haor. This study significantly enhances knowledge of trichodinid diversity, distribution, and ecological interactions in Bangladesh, providing essential baseline data for future parasitological research and management strategies. This thesis is submitted for the degree of Doctor of Philosophy.