Mobility of phosphine-susceptible and -resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) after exposure to control release materials with different active ingredients

Long-lasting insecticide netting (LLIN) with deltamethrin is commercially available and has successfully been used to impair mobility and prevent infestation by stored product beetles. Different control release materials with novel modes of action for food facility IPM programs might improve resistance management and significantly reduce the risk of phosphine-resistant populations by providing multiple barriers to infestation at a facility. In this study, we evaluated the efficacy of different control release material (LLIN or bag) with different active ingredients  LLIN (deltamethrin), and bag (permethrin or indoxacarb or dinotefuran) and compared it to control netting or bag without insecticide in reducing movement of phosphine-susceptible and -resistant Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). Adults were exposed for 30 s, 2-, or 60 min, and their movement was assessed for 1 h immediately after exposure, or 24 and 168 h afterwards using video-tracking and Ethovision software. We recorded how the total distance traveled and velocity of adults varied. Overall, we found that exposure to LLIN with deltamethrin is most effective in both phosphine susceptible and resistant insect species as compared to other bag with other active ingredient used in this study. Importantly, LLIN with an active ingredient deltamethrin has been found to be effective against phosphine- resistance species along with phosphine susceptible species. Our results demonstrate that LLIN incorporated with deltamethrin can be used for resistance management programs and helps to combat phosphine-resistant populations.