Efficacy of spirotetramat and imidacloprid against Thrips hawaiiensis on banana plants by flower injection method and their residues in fruit

Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae) is an important pest on banana in China. However, there is no effective control method for this insect. In this study, the control efficiencies of 22.4% spirotetramat suspension concentrate (SC) and 70% imidacloprid water dispersible granule (WG) aganist T. hawaiiensis by banana flower injection method were studyed. And a method using ultra high performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) was employed in the determination of spirotetramat and imidacloprid residues in fruit after banana flower injection. The efficacy trials showed that 22.4% spirotetramat SC and 70% imidacloprid WG were applied once at 0.12 and 0.18 g a.i. per plant in initial budding of banana by flower injection, the control efficacy on T. hawaiiensis were 89% and 86%, respectively. The residue detection results showed that the residue half-lives of spirotetramat and imidacloprid in banana fruit were 9.2 and 6.5 days, respectively. And 95 days after applied, their residues were not detected in the banana mature fruit. This study showed that banana flower injection of spirotetramat and imidacloprid had a good control efficacy on T. hawaiiensis and safety used in banana field, and it could be recommended to alternate use in banana orchards.