A comparison between the impact of sulfuryl fluoride and methyl bromide fumigations on stored-product insect populations in UK flour mills

The impact of sulfuryl fluoride and methyl bromide fumigations upon populations of flour beetles (Tribolium spp.) and of Mediterranean flour moth (Ephestia kuehniella), was evaluated in UK flour mills. Two mills were selected for fumigation with sulfuryl fluoride and two mills for fumigation with methyl bromide. Traps baited with aggregation pheromone lure and an oil-based food attractant were used to monitor populations of rust red flour beetle and confused flour beetle. For the monitoring of Mediterranean flour moth, sticky traps baited with a pheromone lure were used. Traps were placed inside the mill buildings within the areas selected for fumigation. Infestation levels of the insects were monitored for 1–2 weeks prior to fumigation and for a total of 12 weeks post-fumigation. From the calculated percentage reduction in insects trapped per day during the post-fumigation monitoring period it was clear that sulfuryl fluoride fumigations had good efficacy against infestations of Tribolium confusum and E. kuehniella, and compared very favourably with the efficacy of methyl bromide. The absence of T. castaneum in traps pre-fumigation meant that the efficacy of sulfuryl fluoride against this species could not be assessed in this investigation. Indian meal moth, Plodia interpunctella, was also detected in some mills but only post-fumigation.