PJB-2020-18
Evaluation of the insecticidal activity of Adhatoda vasica and Thevetia peruviana leaves extract against Subterranean Termites Microtermes obesi (Isoptera: Termitidae)
Mazhar Iqbal Zafar
Abstract
Termites are the main class of pests that impart detrimental effect on production of crops. Various synthetic insecticides have been used to control the termites however, these pesticides get assembled in plants and create the hazards of biomagnification leading to serious health problems for humans and livestock. Therefore, plant-origin pesticides have been discovered as a safer alternative that are easily biodegradable in contrast to synthetic pesticides. Undertaken study is intended to explore the anti-termite potential of Adhatoda vasica and Thevetia peruviana revealed by investigating the detrimental impact of their crude extracts on mortality and tunneling activity of M. obesi. Moreover, repellency grading of tunneling activites of M.obesi at different concentrations crude extracts was also checked. Mortality of Microtermes obesi was investigated by treating the soil and filter paper with different concentrations of methanolic and aqueous extracts. In soil treated assay, least LT50 value was shown by 40% Aqs. extract of A. vasica (36.00 µg/ml) followed by MeOH. extract of T. Peruviana therefore, aforementioned extracts were considered most proficient. Results of filter paper assay were found in close resemblance to those revealed by treated soil assay. Aqs. extract of T. Peruviana and MeOH. extract of A. vasica showed least LT50 value i.e. 28.61 and 29.88 µg/ml respectively, so these extracts were considered to be highly active. Tunneling activity of M. obesi was also investigated at different times with varying concentrations of test extracts. Termites showed minimum tunneling activity at 40% MeOH extract of T. Peruviana (5 mm2) followed by MeOH extract of A. vasica (38 mm2) thus indicating that toxicity of phytoconstituents might have seized the movement of termites. Repellency grading of Tunneling Activites of M.obesi at different concentrations of methanolic extracts was also done. 40% MeOH extract of T. Peruviana was graded as very very strong repellent whereas 40% MeOH extract of A. vasica was graded as very strong repellent. It is concluded that crude extracts of subject plants are potential candidates to slay the workers of M. obesi.
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