Resistance to Phosphine in Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) collected from wheat storages in Brazil

Samples of R. dominica were collected from control failures occurring at central storages in three southern states of Brazil between 1991 and 2003. Resistance to phosphine was characterised in these samples using a range of tests including discriminating doses, full dose-response assays and mixed-age culture assays. Of the 19 samples tested, five were diagnosed with weak resistance and 14 with strong resistance. Resistance to phosphine in Brazil is widespread and strongly resistant strains are common. There is an urgent need to improve fumigation and pest management practices in Brazil to manage phosphine resistance