title: English field samples of Thrips tabaci show strong and ubiquitous resistance to deltamethrin.
abstract: BACKGROUND
  Onion thrips, Thrips tabaci Lindeman, is a prevalent pest of glasshouse and field vegetables, such as leeks and salad onions. Pesticides are the main option for control, but this approach risks the evolution and spread of insecticide resistance. In the light of anecdotal reports in the United Kingdom of poor efficacy of pyrethroids against T. tabaci, thought to be primarily a consequence of resistance, the responses to deltamethrin of ten English samples of T. tabaci, collected from field leeks and salad onions in 2006, were measured to establish the level and prevalence of potential resistance to this compound.
  
  
  RESULTS
  All the samples showed significant deltamethrin resistance that was comparable or slightly lower than the maximum level reported previously for T. tabaci from New Zealand.
  
  
  CONCLUSIONS
  The mechanism(s) conferring deltamethrin resistance remain unknown at present but are likely to extend to other synthetic pyrethroids approved for use against this species. The findings suggest that these compounds are unlikely to give satisfactory control of T. tabaci in England and have stimulated the recommendation to use alternatives.
authors.affiliation: Department of Plant and Invertebrate Ecology, Rothamsted Research, Harpenden, Hertfordshire, UK. stephen.foster@bbsrc.ac.uk
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Foster
authors.forename: Kevin
authors.initials: K
authors.lastname: Gorman
authors.forename: Ian
authors.initials: I
authors.lastname: Denholm
mesh_terms: D000818:Animals; D004739:England; D005260:Female; D007313:Insecta / Q000502:physiology*; D007305:Insecticide Resistance; D007306:Insecticides; D007928:Lethal Dose 50; D008297:Male; D009570:Nitriles; D011722:Pyrethrins
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin