title: Phosphine Resistance in Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) Collected From Grain Storage Facilities in Oklahoma, USA.
abstract: Phosphine gas (PH3) is one of the most commonly used fumigants for controlling stored-grain pests worldwide. We estimated the discriminating dose for Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) adult insects using a laboratory susceptible strain. This discriminating dose was then used to determine presence or absence of PH3 resistance (resistance frequencies) in 19 field-collected populations of C. ferrugineus from Oklahoma, United States. The discriminating dose was estimated as 56.2 ppm of PH3 over a 20-h exposure period at 25 °C. Discriminating dose bioassay results showed that PH3 resistance was present in all 19 populations of C. ferrugineus tested. However, five populations-Stillwater (Stil), Enid Terminal 1 (ET-1), Enid Terminal 2 (ET-2), Johnson-Enid population (JE), and DK Farm 20 population (DK Farm 20) had ≥90% resistance frequencies. LC99 values estimated by probit analyses of dose-response mortality data for the laboratory susceptible strain (Lab-S), JE, and DK Farm 20 were 7.3, 636.4, and 968.6 ppm, respectively, over a 3-d exposure period. The level of resistance in DK Farm 20, the most resistant population, was 133.5 times that of the susceptible laboratory strain. This study shows that PH3 resistance in C. ferrugineus may be widespread in Oklahoma. Based on this study, there is a need for a wider PH3 resistance survey in grain-growing regions of Oklahoma and United States. Furthermore, results show there is a need to develop PH3 resistance management strategies for C. ferrugineus and other stored-product insect pest species to combat resistance and ensure continued effective future use of PH3.
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 (charles.e.konemann@okstate.edu; jorigtoo.chen@okstate.edu; george.opit@okstate.edu; sangautam@ucanr.edu; nisha.shakya10@okstate.edu).
authors.forename: C E
authors.initials: CE
authors.lastname: Konemann
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 (charles.e.konemann@okstate.edu; jorigtoo.chen@okstate.edu; george.opit@okstate.edu; sangautam@ucanr.edu; nisha.shakya10@okstate.edu).
authors.forename: Z
authors.initials: Z
authors.lastname: Hubhachen
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 ( charles.e.konemann@okstate.edu ; jorigtoo.chen@okstate.edu ; george.opit@okstate.edu ; sangautam@ucanr.edu ; nisha.shakya10@okstate.edu ).|Corresponding author, e-mail: george.opit@okstate.edu.
authors.forename: G P
authors.initials: GP
authors.lastname: Opit
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 ( charles.e.konemann@okstate.edu ; jorigtoo.chen@okstate.edu ; george.opit@okstate.edu ; sangautam@ucanr.edu ; nisha.shakya10@okstate.edu ).|Current Address: Kearney Agricultural Research and Extension Center, 9240 S Riverbend Avenue, Parlier, CA 93648.
authors.forename: S
authors.initials: S
authors.lastname: Gautam
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 (charles.e.konemann@okstate.edu; jorigtoo.chen@okstate.edu; george.opit@okstate.edu; sangautam@ucanr.edu; nisha.shakya10@okstate.edu).
authors.forename: N S
authors.initials: NS
authors.lastname: Bajracharya
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D002523:Edible Grain; D005260:Female; D061353:Food Storage; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D009825:Oklahoma; D010720:Phosphines / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D010720:Phosphines; C044646:phosphine
keywords: fumigation; resistance frequency; resistance management; rusty grain beetle; stored-product pest