Toxicity of insecticides to populations of tomato borer Tuta absoluta (Meyrick) from Greece.

BACKGROUND

Tuta absoluta (Meyrick), in only a few years, has become a serious threat to global tomato production. Depending on the cropping system and infestation pressure, T. absoluta control may rely heavily on insecticide applications. By means of a validated IRAC bioassay method, the toxicity of all insecticides registered for T. absoluta control in Greece has been estimated. A non-registered pyrethroid insecticide was also included in this study.

RESULTS

Low heterogeneity was detected in the populations tested with most insecticides. The LC50 ranged from 0.31 to 1.31 mg L(-1) for flubendiamide, from 0.12 to 0.53 mg L(-1) for chlorantraniliprole, from 0.03 to 0.12 mg L(-1) for emamectin benzoate, from 0.08 to 0.26 mg L(-1) for spinosad, from 31.8 to 159.5 mg L(-1) for metaflumizone, from 1.73 to 17.5 mg L(-1) for indoxacarb, from 530 to 2038 mg L(-1) for chlorpyriphos and finally from 475 to 794 mg L(-1) for cypermethrin. The variability of the LC50 values among the tested populations was low (RR under 5×), except for indoxacarb (RR = 10×). In the absence of a reference strain, comparisons with the recommended label rates were performed. Evidence of potential control failures was detected using probit analysis estimates for cypermethrin, chlorpyriphos and metaflumizone.

CONCLUSIONS

For most registered insecticides, a solid set of baseline data has been presented that can be used in future resistance monitoring studies. The interaction of metaflumizone with T. absoluta has been discussed, and for chlorpyriphos it is suspected that the resistance level is underestimated with the present dataset. Finally, it has been demonstrated that the pyrethroid cypermethrin would provide insufficient control of the pest.