SUSCEPTIBILIDAD A INSECTICIDAS EN TRES POBLACIONES MEXICANAS DEL TRIPS DEL LAUREL, Gynaikothrips ficorum (Marchal) (THYSANOPTERA: PHLAEOTHRIPIDAE) SUSCEPTIBILITY TO INSECTICIDES IN THREE MEXICAN POPULATIONS OF THE LAUREL THRIPS, Gynaikothrips ficorum (Marchal) (THYSANOPTERA: PHLAEOTHRIPIDAE)

Gynaikothrips ficorum (Marchal) is a pest of the laurel tree in urban zones and insecticides are possibly used for its control, but its initial response to these products is unknown. Therefore susceptibility of various populations of this species was determined (Texcoco, Cordoba and Tlayacapan) to the insecticides permethrin, cypermethrin, diazinon, malathion, methyl oxydemeton, methyl parathion, endosulfan and methomyl. The Texcoco population was used as reference to make comparisons of the response. At 24 h of exposure, the confidence levels of the CL 50 of the three populations overlapped in the insecticides cypermethrin, diazinon, malathion and methyl oxydemeton; but they did not overlap in Cordoba and Tlayacapan with Texcoco, for permethrin, methyl parathion, endosulfan and methomyl. For Cordoba and Tlayacapan with cypermethrin, the resistance proportion (RP 50 ) was 0.88 and 0.53’; with diazinon, 0.3 and 0.29’; with malathion 1.04 and 1.02’; with methyl oxydemoton 0.74 and 7.18’; with methyl parathion 8.4 and 4.63’; with endosulfan 1.19 and 0.2’, and with methomyl 0.11 and 0.53’. At 95 % mortality, only in Tlayacapan and for endosulfan (RP 95 =0.03), the fiducial limits did not overlap with the other two populations. The values obtained at 48 h of exposure followed the same tendencies found at 24 h. These response values correspond to a susceptible state and can be used as comparison reference.