High-dose strategies for managing phosphine-resistant populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae).

Background: Rhyzopertha dominica is a serious pest of stored grains and many populations have resistance to the fumigant phosphine. Some populations contain beetles with a 'strong resistance' phenotype. Recent work found the LC values for two strong-resistant populations recently studied in North America, Belle Glade and Minneapolis were 100- and 595-fold higher, respectively, compared to LC of a lab-susceptible strain.

Evaluation of Knockdown Bioassay Methods to Assess Phosphine Resistance in the Red Flour Beetle, (Herbst) (Coleoptera: Tenebrionidae).

Resistance to the fumigant phosphine in occurs worldwide. This study evaluated tests based on adult knockdown time, the time for a beetle to become immobile, when exposed to a high concentration of phosphine. We recorded knockdown times of beetles that remained completely still for 30 s when exposed to 3000 ppm of phosphine in a large, gas-tight glass tube.