Dicofol resistance in Tetranychus cinnabarinus: resistance and stability of resistance in populations from Antalya, Turkey

Resistance against dicofol was investigated in the carmine spider mite, Tet ranychus cinnabarinus. Higher resistance levels were detected by leaf resid ual bioassays than by topical bioassays, both done using a Potter spray tow er, in almost all populations of T cinnabarinus examined from Antalya, Turk ey. For instance, the resistance level at LC95 was 17.5-fold in topical bio assays but 58.9-fold in leaf residual bioassays for the population collecte d from greenhouses in the Topcular district. There were differences of resi stance levels at LC95, ranging between 2.6- and 23.9-fold using topical bio assays and between 5.0- and 58.9-fold in residual bioassays, in populations collected from greenhouses from various districts. Populations from cotton showed lower resistance levels against dicofol than populations from green houses. Resistance to dicofol at LC50 as indicated by topical and residual bioassay s increased 19.7- and 100.7-fold, respectively, in a colony from the labora tory strain of T cinnabarinus selected with dicofol alone for 16 cycles. Ho wever, the dicofol resistance at LC50 increased 19.4- and 52.0-fold in anot her colony selected in rotation with dicofol and tetradifon for six and eig ht cycles, respectively. The changes in resistance to dicofol 5 months afte r the selection ceased were as follows: in the colony selected for dicofol alone, using topical and residual bioassays, the resistance levels at LC50 decreased to 11.7- and 99.1-fold, respectively, and in the colony selected in rotation with dicofol and tetradifon to 10.8- and 15.8-fold, respectivel y. (C) 2001 Society of Chemical Industry.