Vol. 11, Issue 7 (2022)

Author(s):
Pramod Das, E Sumathi, V Baskaran, M Jayakanthan and M Murugan

Abstract:
Spider mites are important crop pests that rapidly develop resistance to Acaricides. Tetranychus urticae Koch collected from Hosur, Tamil Nadu during 2022 was reared in the laboratory for more than 10 generations and its susceptibility to selected three Acaricides was determined after every 2 generations. The lowest LC₅₀ values of selected Acaricides in the 10 generations viz., propargite - 1.81ppm; fenazaquin - 2.20ppm, and spiromesifen - 1.30ppm were used as the baseline data for determining the level of resistance in the field populations of T. urticae. Mites samples collected from gerbera crop were subjected to bioassay with three major Acaricides viz., Propargite, fenazaquin, and spiromesifen. The level of resistance to spiromesifen(274.98 folds) was high for all three Acaricides tested. The consequence of acaricide resistance on the development of male mites was apparent as the mean duration of development of males in the resistant Hosur population was significantly more (12.2 days versus 10.4 days) than in the laboratory susceptible population.