Preliminary determination of median lethal dose of Azadirachta indica (A. ) Juss bark extract against Boophilus microplus

RESUMO

The study was carried out in order to determine the effective dose of Azadirachta indica as an acaride. From a range of effective doses, nine (9) test doses ranging from zero (0) parts per million to one hundred and fifty parts (150) per million were selected. The test species Boophilus microplus was subjected to a standard bioassay. A dose response curve was plotted of percentage mortality of B. microplus against logarithmic dosage of A indica. The lethal dose, LD50 and LD100 were also determined. The LD50 was 30.20 parts per million and LD100 was found to lie between 80 and 100 parts per million. Regression analysis was performed to verify correlation of data. The data proved to be linear with a correlation coefficient of 0.89. The results of this study indicate that when the dose required to achieve 50 percent mortality is compared to average yield of A. indica bark extract obtained in previous studies (Maharaj et al 2003), the extract appears to be feasible with respect to production for use as a prospective pesticide. This is an important point for consideration as the failure in the commercialization of many plant products is often due to the yields being too low. The bark extract of Azadirachta indica has thus far proven to be worthy of consideration for further development as a phytoacaricide