Md. Abul Kalam Azad*
Department of Food Engineering & Tea Technology, Shahjalal University of Science & Technology, Sylhet-3114, Bangladesh
Iftekhar Ahmad
Department of Food Engineering & Tea Technology, Shahjalal University of Science & Technology, Sylhet-3114, Bangladesh
Extracts; Medicinal Plant; Tea; Thrips; Potentiality
Habibnagar Tea Estate and Khan Tea Estate in Sylhet, and Baraoora Tea Estate in Moulvibazar district of Bangladesh
Pest Management
Tea leaves were used as the basic elements for this study which were infected by thrips. These infected leaves were collected from Habibnagar Tea Estate and Khan Tea Estate in Sylhet, and Baraoora Tea Estate in Moulvibazar district of Bangladesh. Climate of this region is considered sub-tropical monsoon with three distinct seasons: pre-monsoon season (February to April), monsoon season (May to August) and winter season (September to January). It was observed that about 1400 mm of annual rainfall is a critical limit and the monthly mean temperature is between 18.33°C to 29.44°C seem unfavorable for tea production in Bangladesh.
In this study, five plants extracts were used. The plants were Monochoria vaginalis (Bhat Meteka/ Panee Kachu), Cassia alata (Dadmurdan), Nerium odoratum (Karabi/Raktakarabi), Annona squamosa (Ata/Ata Phol) and Mikania cordata (Refusilata/Jarmanilata). The leaf of five plants were collected and dried in the sun. Fully dried leaf is grinded into fine powder and then placed into 50% alcohol as solvent. The solvent to sample ratio were 4:1. The conical were screw caped and placed in a shaker at room temperature for 24 h at 100 rpm. After 24 h, the extracts were filtered using a muslin cloth and then re-filtered using Whatman filter paper No.1. The extracts were labeled accordingly and preserved in the refrigerator at 4°C, till further work. The collection of thrips affected plants were repeated for three times. For each replication, four densities i.e., 1%, 5%, 10% and 15% concentration of extract were used to observe the number of mortalities of thrips out of total 12 thrips for each plant. The plant leaves were used to get the essence of plants using 50% alcohol and used it on the leaves in different concentrations. At the same time different duration of mortality of thrips were also observed. The experiment was designed to find out the potentiality of plant extracts for the mortality of thrips based on concentration and duration of time, and also find out the impact of different concentrations of extract on the mortality of thrips among the extracted plants. The plants were collected randomly from different places of Bangladesh. A total of 60 samples (thrips affected leaves), 12 for each plant were used in this study. Using in vitro method, 5 ml essence of plants were used for each sample. The laboratory work was carried out in the Department of Food Engineering and Tea Technology of Shahjalal University of Science and Technology, Sylhet, Bangladesh during March, 2019 to August, 2019.
Data analysis was carried out using analysis of variance (ANOVA). One-way ANOVA test is a widely used parametric test that is used to determine whether more than two groups have the same means or not (Osteragova and Ostertag, 2013). In this experimental study, ANOVA was used to find out whether there has significance difference in the average mortality of thrips among the five type of plants for the same concentration. For significance difference in the mortality of thrips for different plants, the Post hoc tests were applied to find out the significantly different pairs of plants extracts. To find out the impact of different concentration on the mortality of thrips, a Poisson regression model was applied. Poisson regression model was applied here because of the nature of the dependent variable, the number of mortalities of thrips which follows approximately a Poisson distribution. However, the Poisson loglinear regression model for the expected number of the occurrence of deaths of the thrips (µ).
Where, µ is the number of mortalities of thrips and X is the densities of the concentration (categorical type). Because of the small number of replicates and slight violation of equi-dispersion assumption having underdispersion among samples, the confidence intervals were found to be more compact which was not major concern in this study. However, to eliminate the influence of under-dispersion, robust estimates were presented in the results.
Rajshahi University Journal of Environmental Science, 8: 43-50, 2019
Journal