Variation in mortality among populations is higher for pymetrozine than for imidacloprid and spiromesifen in Trialeurodes vaporariorum in greenhouses in Finland.
BACKGROUND
Insecticide resistance in Trialeurodes vaporariorum W. is unknown in the species' northern distribution range where it inhabits mainly commercial greenhouses. Resistance development in whiteflies feeding on year-round crops in greenhouses is possible owing to the use of chemical treatments to back up biocontrol. The authors tested the response levels to spiromesifen, pymetrozine and imidacloprid in whiteflies collected from seven greenhouses within a 35 km radius in western Finland.


RESULTS
All except one (PR) population had LC50 values below the recommended concentrations for the tested compounds. However, some populations showed reduced susceptibility to pymetrozine in comparison with the reference susceptible population. Resistance ratios to pymetrozine were highly variable (resistance ratio 0.5-39.7), even among closely located greenhouses, and higher than those for imidacloprid (resistance ratio 1.05-10.5) and spiromesifen (resistance ratio 0.8-11.5). LC50 values and application frequencies of pymetrozine correlated positively among the sampled populations.


CONCLUSIONS
High variation in resistance levels to pymetrozine among populations within natural whitefly dispersal limits reflects variation in the usage of this compound among individual greenhouse crop producers. Thus, resistance management is recommended at the individual greenhouse crop producer level, even in a dense production cluster. © 2014 Society of Chemical Industry.
MTT Agrifood Research, Plant Production Research, Jokioinen, Finland; Centre of Excellence in Biological Interactions Research, Department of Biological and Environmental Science, University of Jyväskylä, Finland.
Irina
I
Ovčarenko
Leena
L
Lindström
Kari
K
Saikkonen
Irene
I
Vänninen
D000818:Animals; D005387:Finland; D006430:Hemiptera / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology*; D010571:Pest Control / Q000379:methods; D013141:Spiro Compounds / Q000494:pharmacology*; D014227:Triazines / Q000494:pharmacology*
D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D013141:Spiro Compounds; D014227:Triazines; C082359:imidacloprid; C480311:pymetrozine; C521569:spiromesifen
adulticide; dispersal; greenhouse whitefly; larvicide; resistance; treatment history