| dc.description.abstract | Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a very
serious pest worldwide, causing considerable damage to vegetables, flower and fruit
crops. The acaricidal, ovicidal and repellent activity of Aloe vera L. (Asphodelaceae) leaf
extracts using four solvents were evaluated against T. urticae under laboratory
conditions. The A. vera leaf extracts were tested against T. urticae at 0.25, 0.50, 1.0 and
2.0% concentrations. The results showed that all the extracts had toxic and repellent
effects on two-spotted spider mite. Mortality percentage was gradually increased with
the increase of doses. The acetone extract showed the highest mortality (95%) of adult
females followed by ethanol (83%) at 2% concentration. The LC50 values of acetone,
ethanol, methanol and petroleum ether extract for adult females were 0.446, 0.667, 0.953
and 1.279, respectively and for eggs were 0.950, 1.406, 2.115 and 3.312, respectively.
Ethanol extract was found more effective as repellent against adult females of T. urticae
followed by acetone, methanol and petroleum ether causing reduction in egg production
per female by 96, 94, 85 and 83%, respectively. In residual test, the acetone extract
showed the highest mortality (49%) at 1 hour after treatment followed by ethanol (43%),
methanol (29%) and petroleum ether (25%). The percent of mortality decreased after 48
and 72 hours after treatments. The results suggested that A. vera has a great potentiality
to develop as a botanical acaricide for T. urticae control. | en_US |
