The acaricidal effect of ethanolic extracts of Chenopodium quinoa Willd. on Tetranychus urticae Koch (Acari: Tetranychidae).

Abstract

Ethanolic extracts obtained from the seed coat of Chenopodium quinoa Willd. were evaluated for their acaricidal effect on different stages of the carmine spider mite Tetranychus urticae Koch. At 72 h after application of the extracts directly on the adult females, mortalities ranged from 30% to 93%, with concentrations of 6.11, 7.61 and 9.11% w/v producing the best results. The lethal effect of the extracts on the nymphs of T. urticae manifested at 24 h after inoculation, with mortality rates ranging between 50 % and 99 %. The extracts of C. quinoa had no lethal effect on the eggs of T. urticae. At 120 h post-application, between 76% and 89%of the larvae had hatched. The extracts showed a repellent effect on adult females of T. urticae. Oviposition by female T. urticae was not affected by application of sublethal concentrations of the extract. The survival of juveniles whose mothers were sprayed with the extracts ranged between 17 % and 48 %, showing a sublethal effect of the extracts on the offspring. Lethal concentrations of the extract of C. quinoa for adult females of T. urticae were determined as 1.24 % w/v (LC50) and 4.34 % w/v (LC90).