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Impact of habitat type and floral resource availability on ground-nesting bee establishment in an agro-natural landscape
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Ekanayake, E.M.D.; Karunaratne, W.A.I.P.; Jayasuriya, K.M.G.G.; Hemachandra, K.S.; Karunarathna4, A.K.
In agroecosystems, ground-nesting bees are crucial for efficient pollination. Ground-nesting bees are susceptible to habitat degradation and resource loss. Habitat destruction has a negative impact on the bee pollination. The effect of changes in habitat and resource availability on ground- nesting bee species composition remains poorly understood. The present study investigates how changing habitat and floral resources affect the species composition of ground-nesting bees. The research was conducted at Meewathura Farm in Peradeniya, where three distinct habitats were established: peripheral weedy, crop, and ornamental habitats. The ground nests of bees and their species, along with floral resources (number of open flowers), were recorded weekly during three developmental stages of the crop in two consecutive years (2021-2023) during the Yala and Maha seasons. Six ground-nesting bee species: Lasioglossum serenum, Leuconomia sp., Lipotriches exagens, L. edirisinghei, L. pulchriventris, and Patellapis kaluterae, (F: Halictidae) were identified. Ground-nesting bee species composition significantly differed among habitats (p = 0.0001). Results revealed that ground-nesting bees were more likely to nest within crop habitats (328 nests) than in peripheral weedy and ornamental habitats (269 and 244 nests, respectively). A weak but significant positive correlation existed between ground nests and their species richness with open flower abundance (R² = 0.230, R² = 0.197, respectively). Significant variations in ground nests and ground-nesting bee species richness were observed across seasons and years (p = 0.0001). Ground-nesting bee species composition varied with floral resources, habitats, seasons, and years, but these factors interacted negatively. A high proportion of bare grounds in crop habitats serve as dwellings for ground-nesting bee establishments. This study highlights the importance of habitat types and resource availability to promote the coexistence and composition of ground-nesting bees, thus maintaining their vital role as pollinators in agroecosystems.
Pantala flavescens (wandering glider) and Ceriagrion coromandelianum (yellow waxtail) as predators of preimaginal stages of aedes aegypti (diptera: culicidae) in fresh and brackish water habitats from Jaffna,Northern Sri Lanka.
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Arthiyan, S.; Tharsan, A.; Eswaramohan, T.; Surendran, S.N.
The present study aimed to report the efficiency and the potential use of natural predators as biological control agents to control the preimaginal stages of primary dengue vector Aedes aegypti in the Jaffna peninsula as preliminary research. Nymphal stages of dragonfly Pantala flavescens and damselfly Ceriagrion coromandelianum were collected from local ponds. They were acclimatized to the freshwater (0 ppt /g L⁻¹) and brackish water (10 g L⁻¹) to conduct the experiments against the standard laboratory colonies (0 g L⁻¹ and 10 g L⁻¹) of mosquito Ae. aegypti. The experiment was conducted in triplicates and repeated thrice with different individual predators. Hundred, third instar larva of Ae. aegypti were introduced, and the predatory activity was recorded every 24 hours up to 72 hours. The prey density was maintained by replenishing the same number of larvae. The predatory rate (PR), predatory impact (PI), and clearing rate (CR) were calculated for both predators for both salinities. The results indicated that both predators show promising efficacy in controlling the mosquito larvae, where the clearing rate of the P. flavescens was significantly high (p < 0.05) over C. coromandelianum in both freshwater (p = 0.0003), and brackish water (p = 0.0003) experiments, and the predatory impact and the predatory activity were also exhibited considerably high in the dragonfly P. flavescens both in the freshwater and brackish water environments. The damselfly C. coromandelianum shows an increasing trend in its clearing rate of prey over time, with slight variations based on salinity. The preliminary results of the study suggest that these natural predators could be introduced as a green solution to control the preimaginal stages of mosquito species in both freshwater and brackish water habitats, and this could potentially aid in reducing the prevalence of dengue and other mosquito-borne diseases in coastal areas like Jaffna Peninsula.
Risk factors of Dengue hemorrhagic fever among adult dengue patients in the Western Province of Sri Lanka: a case-control study
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Jayasinghe, C.D.; Deerasinghe, D.S.A.F.; Tissera, K. H.; Wijewikrema, A.
Dengue infection has spread rapidly within countries and across regions in the past few decades, resulting in an increased frequency of epidemics. Infection with any of the dengue virus (DENV) serotypes may result in a broad spectrum of clinical symptoms ranging from a mild flu-like syndrome, dengue fever (DF), to the most severe forms of the disease, dengue hemorrhagic fever (DHF), with coagulopathy and permeability. The signs and symptoms of DHF usually arise late in the disease course when the fever has subsided, making it difficult to predict. Hence, identifying risk factors that accurately predict progress to DHF would significantly contribute to implementing proper intervention and treatment strategies for those at greater risk. This case- control study included 136 adult DHF patients (18 years and above) as cases and 136 DF patients (18 years and above) as controls from four leading hospitals of the Western Province in 2022 to identify the independent risk factors of DHF among adult dengue patients. Participants were recruited for the study by applying consecutive sampling techniques, and independent risk factors under the categories of socio-demographic, clinical and serological were assessed using a questionnaire survey with informed consent. Chi-square and binary logistic regression were performed to identify potential risk factors. Though 20 factors were significant in the bivariate analysis, when the logistic regression was performed to adjust the confounding effect, only six independent predictors showed significant associations with the DHF patients compared to DF patients: Demographic factors such as belonging to other ethnic groups (Tamils, Muslims, Burghers) compared to Sinhalese (aOR = 0.143, 95% CI: 0.043 – 0.470), clinical manifestations; such as abdominal pain (aOR = 3.172, 95% CI: 1.381– 7.285), altered consciousness/ confused state (aOR=8.395, 95% CI: 1.527 - 46.161), systolic blood pressure on admission (aOR=1.014, 95% CI: 1.002-1.027), right hypochondrial tenderness (aOR= 10.839, 95%CI: 3.063 - 38.347), and laboratory characteristics; serum creatinine on admission (aOR= 1.028, 95%CI: 1.018 - 1.038) were identified as significant risk factors of progression of DHF of adult patients (p<0.05). Collectively, the results of this study strengthen the understanding of the risk factors of DHF adult patients of the Western Province in Sri Lanka that could be identified from the patient's clinical parameters and by results of low-cost routine laboratory investigations.
Cytokine responses of different categories of lymphatic filariasis patients in Galle District, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Gunaratna,I.E.; Jayasinghe, C.D.
Lymphatic Filariasis (LF) is one of the neglected tropical diseases (NTDs) which cause lifelong disfiguring complications. A complex network of innate and adaptive immune responses largely contributes to establishing a wide array of pathologies of filariasis, which are clinically classified into chronic, acute, and asymptomatic categories. Generally, in in vitro assays, filariasis infection is characterized by the predominant Th2 response. However, there is limited evidence of immunopathology of filariasis from the in vivo setting, particularly from different clinical categories. Therefore, the present cross-sectional study was conducted in Galle District in Sri Lanka during 2021-2022 to evaluate the pro and anti-inflammatory cytokine responses of different disease categories of filariasis: endemic controls, asymptomatic carriers, cryptic, chronic patients, and control groups. A total of 250 individuals (50/group) were included in the study. Participants were recruited based on random sampling frames, and basic demographic information was obtained from a self-administered questionnaire. Serum levels of cytokine (proinflammatory (Interferon-gamma: IFNɤ) and anti-inflammatory (Interleukin: IL10) were assessed using a sandwich ELISA procedure. Statistical analysis was done using SPSS software. Chi-square test and one-way ANOVA with the Bonferroni test were done to compare the findings between groups. A higher male preponderance of positivity was observed among disease groups: antigen-positive cryptic patients (Z=2.3, P<0.05), microfilaria-positive asymptomatic carriers (Z=4.0, P<0.001), and chronic patients (Z=1.1, P=0.25). Chronic complications were higher with older ages (p<0.05). Serum IFNɤ levels were significantly higher in chronic (273±10.34 pg/mL), endemic control (211.57±5.78 pg/ml), and cryptic (222.37±6.54pg/mL) compared to the non-endemic control (193 ± 6.54 pg/mL) (p<0.05). Asymptomatic carrier patients had a significantly higher IL10 level (151.3±23.5 pg/mL) compared to non-endemic control (61.99 ± 2.96 pg/mL) (p<0.05). Also, the IFNɤ/IL10 (Th1/Th2) was significantly higher in both cryptic (5.58±0.39) and chronic (7.05±0.47) groups compared to the control (3.59±0.24) (p<0.05). This study reports a predominant Th1 response in chronic patients, which contradicts the traditional immune response for exposure to antigens in filarial infection but supports immune response due to chronic complications and the difference in cytokine profile of older patients to younger patients. Thus, expanded studies are warranted for a comprehensive understanding of cytokine responses that could establish biomarkers of the progression of filariasis.
Daily dietary intake of total phenolics and total flavanoids from consumption of rice (Oryza sativa l.) Varieties commercially available in Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Gunawardana, J.W.; Gunawardena, S.A.; Perera, I.C.; Witharana,C.
Asian rice (Oryza sativa L.), the dietary staple of Sri Lanka, contains bioactive compounds such as phenolics and flavonoids with multiple therapeutic benefits. As alterations in the net bioavailability occures during domestic cooking, the analyses should be carried out in cooked, table-ready form to reach precise dietary estimations. Total phenolic (TPC) and total flavonoid content (TFC) were quantified in cooked grains of 25 composite rice samples representing 10 commonly consumed varieties available in Sri Lanka. The best varieties with the highest contribution to recommended dietary intakes was determined. Aqueous extracts of lyophilized cooked grain powder (n=25) were quantified for TPC and TFC spectroscopically (triplicates) and expressed as Gallic Acid Equivalents (GAE) and Quercetin Equivalents (QE) mg per 100g portion of cooked rice. Data extrapolated with median rice consumption data by Sri Lankan adults (386.5g person-1 day-1). Percentage contribution of TPC was inferred with mean recommended daily intake values at 1.5g person-1 day-1 while TFC was deduced at 0.5g person- 1 day-1 in accordance with dietary recommendations and evaluated across rice varieties; traditional/heirloom (Pachchaperumal (Siyapath-el), Kaluheenati, Suwandel)), improved (Nadu, Samba, Kekulu), imported (Indian Basmati) and pericarp (red/white) colours. The median (Interquartile Range) TPC and TFC for 100g portion of cooked rice was 72.88 (116.52–58.64) mgGAE and 70.20 (80.61–63.06) mgQE, respectively, showing a significant inter-categorical variation (p<0.05). TFC resulted in a similar, non-significant trend (p>0.05). TPC and TFC intakes from traditional varieties were significantly greater than improved or imported varieties (p<0.05). Red pericarp grains contributed a significantly higher percentage than white pericarp grains(p<0.05). The median (IQR) % contribution of TPC and TFC from rice was 18.78% (30.02–15.11) and 54.26% (62.31–48.75), respectively. Higher consumptions (CI75%=447g person-1 day-1) yielded a ~2.8-fold increase in % contribution of TPC and ~1.2–fold increase in TFC. The highest % contribution (TPC=52.52%; TFC=79.35%) resulted in Pachaperumal (Siyapath el) variety, while minimum values (TPC=12.71%; TFC=42.07%) were reported by white Kekulu grains. Imported Indian Basmati reported 13.26% and 49.41% for TPC and TFC, respectively. Sri Lankan rice is a good source of bioactive compounds, and daily consumption of cooked rice contributed to >18% and >50% of the recommended dietary intake of phenolics and flavonoids, respectively.