The present study was carried out to evaluate the toxicity, repellency and fumigant activity of three essential oils that is, Cymbopogen citratus, Mentha arvensis, Eucalyptus citriodora against Periplaneta americana (L.) under laboratory conditions. Of the three tested oils, C. citratus showed the maximum toxicity (20 to 100%) between 2 to 24 h intervals, repellency (100%) and 70 to 100% fumigation after 24 h exposure. E. citrodora oil was found to have least toxicity, repellency and fumigant activity. Percentage mortality (0 to 80%) between 2 to 24 h, 40 to 60% fumigant activity was observed after 24 h at different concentrations. From the present study, it was revealed that three oils were arranged according to the following order of preference that is, C. citratus M. arvensis and E. citriodora.
Microbial control of insect pest of crops using entomopathogens is pest management strategy. Bacillus thuringiensis has a great potential for this purpose. The focus of the present study was to determine the individual and combined effect of different insecticides such as Saraca indica as a botanical insecticide, B. thuringiensis and chemical insecticides against larvae and adults of T. castaneum. Results were analyzed by SPSS probit analysis, LC 50 was noted for all these insecticides and results were compared with each other. According to the results from the individual insecticide B. thuringiensis show high mortality with harmless effect to environment. Synergistic effect with high mortality rate was observed at 24 to 48 h, for both larvae and adults of T. castaneum. From the study it was observed that mortality rate increases as the concentrations increases, and larvae show higher mortality because they were more susceptible to these insecticides as compared to adults. Percentage mortality of T. castaneum in combined bioassay sodium citrate, S. indica, B. thuringiensis and Bifenthrin+cypermethrin was compared with the mortality of individual insecticides. 61% larvae and 55% adult died in combine bioassay at high concentration.
The present research was based on determining the effect of dichlorvos + tetramethrin (3.1% emulsifiable concentrate, EC), Bougainvillea glabra, potassium chloride and Shaf I Bacillus thuringiensis alone or in combination against Tribolium castaneum (Jaculin Du val.) adults and larvae. Bt was isolated from samples, cultured on different media by applying microbial techniques and then crystal protein was isolated from bacteria. The bio-toxicity was analyzsed by SPSS software and showed that larvae are more susceptible and showed significant results as compared to adults. Separate bioassays revealed that Shaf I B. thuringiensis was more toxic at all concentrations followed by an insecticide DDVP+tetramethrin, chemical potassium chloride and the least toxic was B. glabra. In the synergistic effect, highest mortality percentage was shown by the bioinsecticide, B. thuringiensis. All elements whenever combined together, proved to be useful for the control of stored product pests.
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