Context: Medicinal plants contains some pesticidal activities that may control stored product insects.Objectives: To elucidate the insecticidal activity from the stem bark extracts of nishinda (Vitex negundo L.) and their toxicity against red flour beetle, Tribolium castaneum (Herbst) (Tenebrionidae). Materials and Methods:The powdered stem bark (250 g) was extracted with methanol (MeOH), ethyl acetate (EtOAc), acetone and chloroform sequentially. Solvents were evaporated using a rotary evaporator to obtained dry extract, weighed and re-dissolved in the same solvent from which they were extracted for bioassay. Red flour beetles were reared for the experiment in 500 ml beakers containing food medium and kept in a control temperature room (30 ± 0.5 0 C). Residual film bioassay was used to evaluate the toxicity. The adult mortality of T. castaneum (CTC-12, FSS-II and KANO strains) was recorded after 24, 48 and 72 h, but for larvae, the mortality was recorded on 12 th and 20 th larval day after treatment. The mortality percentages were subjected to probit analysis. Results:The LD50 values for first through fourth instar larvae were more or less similar whereas, LD50 for fifth instar larva and adults were the lowest. Among the solvents, methanolic extracts elucidated more toxicity on both adult and larval insects. The degree of toxicity of the extracts according to solvents was MeOH>Pet spt.>acetone>EtOAc. The susceptibility order according to insect strains was FSS-II>CTC-12>KANO. Conclusion:The results suggest the presence of active toxic substances of nishinda acting after consumption or topical application on T. castaneum. Methanolic extracts of the plant provided the most potent and reliable control of the flour beetle.
Context: Viyex negundo Linn. (Verbenaceae) is a beautiful tree which is an erect, large aromatic shrub with quadrangular branchlets possess pesticidal, antibacterial and antifungal properties.Objective: To determine the biological activities (antibacterial, antifungal, brine shrimp lethality bioassay) of the two isolated compounds from methanolic leaf extract. Materials and Methods:Powdered leaves of nishinda were extracted with methanol using Soxhlet's apparatus and subsequent analyses isolated two compounds. Five gram-positive, eight Gram-negative bacterial strains were used for the antibacterial activity using the disc diffusion assay method. The antifungal activities of the isolated compounds were also performed on four pathogenic fungi. Each pure compound was dissolved in 200 µl of methanol to get a concentration 300 µg/10 µl. Minimum Inhibitory Concentrations were determined by serial dilution technique. For brineshrimp bioassay each compound and standard amphicilin trihydrate were dissolved in dimethylsulfoxide to get a five concentrations. Each concentration contained three vials consisting of 10 nauplii in 5 ml of treated sea water. The number of survived nauplii were counted after 24 h and the LD50 values were calculated. Results:The zone of inhibition was prominent for the control (kanamycin) at concentration of 30 µg/disc. At 100 µg/disc Compound 1 exhibited bigger and more prominent clear zone of growth inhibition in all test microorganisms except Shigella shiga. On the contrary, Compound 2 at 100 µg/disc, showed clear zone of inhibition in all bacteria, but inhibition of zones were larger in Compound 1 than Compound 2. Antimicrobial effect of Compound 2 tested on different pathogenic bacteria (MIC 128 µg/ml) and fungi showed that it possesses growth inhibitory effect at various concentrations. MIC of Compound 1 for B. subtilis, S. aureus and S. B-haemolyticus was 64 µg/ml, whereas for P. aeruginosa it was 128 µg/ml ( Table 2). MIC of Compound 2 was 128 µg/ml for B. subtilis, S.-β-haemolyticus and P. aeruginosa whereas it was 64 µg/ml for S. aureus. No fungal activity was observed for Compound 1. Clear inhibition zone was observed for Compound 2 at both concentrations for all of the pathogenic fungi tested. At 100 µg/disc Compound 2 exhibited bigger and prominent clear zone than 50 µg/disc.. Brine shrimp bioassay showed the toxic effect of the both the compounds. Conclusion:The findings indicate promising antibacterial and antifungal activities of V. negundo against life treating pathogens which appears to be an effective material for development of antimicrobial drugs and ecofriendly biopesticides.
Maize is considered as the third most important cereal crop and has more versatile uses in Bangladesh. The study was undertaken to examine the profitability and technical efficiency of maize production as well as to determine the influence of various socio-economic features on farmers land allocation for maize farming in Bangladesh. In doing so, the study utilized the farm-level data collected by the field survey in Lalmonirhat district of Bangladesh. A total number of 60 farmers were selected by using stratified random sampling method among which 36, 20 and 4 farmers were selected under three strata, small, medium and large farmers, respectively. Data were analyzed using simple statistical techniques as well as OLS regression analysis. The comparative analysis among different strata of farmers by this study brought into being that large farmers received higher profit compared to the small and medium farmers. The other results of the study include that maize cultivation helped a lot in improving the nutritional status of the rural people; in creating employment opportunity for them and in increasing household income in the study area. The result of the OLS method suggests that factors like education level, neighbors influence, farm size and higher output price of maize have significant influence upon the choice of farmers land area allocation for maize cultivation in the study area. Based on the findings, this study recommends that proper initiatives must be undertaken by the responsible authority to ensure the efficient use of resources by the maize farmers.Progressive Agriculture 27 (3): 346-354, 2016
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