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

Ethanolic extracts obtained from the seed coat of Chenopodium quinoa Wind. 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).