Comparative toxicities of novel and conventional acaricides against different stages of Tetranychus urticae Koch (Acarina: Tetranychidae)

Adulticidal, ovicidal and nymphicidal effects of different newer acaricides along with some conventional one were evaluated on the life stages of a susceptible laboratory strain of two-spotted spider mite (TSMM), Tetranychus urticae Koch (Acarina: Tetranychidae) using a spray method. Abamectin was found to be the most toxic to the adults (LC50 = 0.39 ppm) followed by fenpyroximate (5.67 ppm), spiromesifen (12.53 ppm), chlorfenapyr (32.24 ppm), propargite (77.05 ppm) and dicofol (146.65 ppm). Hexythiazox was least toxic. There was no egg hatching when eggs were sprayed with one third of the recommended concentration of spiromesifen. This was statistically significantly different from all other treatments (fenpyroximate, chlorfenapyr, propargite, dicofol and hexythiazox) which were, however, at par with each other. Based on the 10th day observations, the ovicidal activity of spiromesifen (100%) was followed by dicofol (7.78% egg mortality) and hexythiazox (6.67%). Almost no effect on hatching was observed in both abamectin and chlorfenapyr treatment (0.54%). In case of propargite, all the treated eggs hatched. Abamectin resulted in highest nymphal mortality (96.05%) followed by dicofol (94.51%), hexythiazox (90.24) propargite (90.00), chlorfenapyr (89.33) and fenpyroximate (86.84%) and all the treatments were at par with each other and statistically different from the control. The present study revealed that abamectin, spiromesifen, hexythiazox, fenpyroximate and chlorfenapyr acaricides can alternatively be used for effective management of the mites.