Acaricidal properties of extracts and major furanochromenes from the seeds of Ammi visnaga Linn. against Tetranychus urticae Koch

The acaricidal and ovicidal efficacy of the methanol extract obtained from Ammi visnaga seeds against Tetranychus urticae was studied. By analyzing the extract, two majority substances belonging to the group of furanochromenes were determined: khellin and visnagin, whose content was determined as 382.3 and 275.2 mg g(-1), respectively. Both these substances were responsible for biological efficacy; nevertheless, visnagin showed a significantly higher efficacy compared to khellin. Adult mortality was studied both for the extract and for visnagin and khellin. The efficacy increased with time; LD50 levels after 72 h from application were estimated as 17, 10 and 981,1 mu g cm(-2), for the extract, visnagin and khellin, respectively. The extract as well as both furanochromenes inhibited the development of eggs and caused their mortality, while LD50 was estimated as 13.3, 0.5 and 1.8 mu g cm(-2), for the extract, visnagin and khellin, respectively. Extract application to plants infested by T. urticae achieved a significant reduction in the counts of all developmental stages on the treated plants. The concentration of 10 mg mL(-1) exhibited the highest efficacy, which was observed at the level of 98.5% on day 10 from the application. The effect of the extract also showed a high persistence. Based on the results of this study, we can recommend the extract from A. visnaga seeds as being highly promising for the development of new botanical acaricides. (C) 2015 Elsevier B.V. All rights reserved.