title: Phosphine Resistance in Adult and Immature Life Stages of Tribolium castaneum (Coleoptera: Tenebrionidae) and Plodia interpunctella (Lepidoptera: Pyralidae) Populations in California.
abstract: Phosphine resistance in stored-product insects occurs worldwide and is a major challenge to continued effective use of this fumigant. We determined resistance frequencies and levels of resistance in Tribolium castaneum and Plodia interpunctella collected from California almond storage and processing facilities. Discriminating doses of phosphine were established for eggs and larvae of P. interpunctella and eggs of T. castaneum using laboratory susceptible strains of the two species. For T. castaneum and P. interpunctella eggs, discriminating doses were 62.4 and 107.8 ppm, respectively, over a 3-d fumigation period, and for P. interpunctella larvae, discriminating dose was 98.7 ppm over a 20-h fumigation period. Discriminating dose tests on adults and eggs showed that 4 out of 11 T. castaneum populations tested had resistance frequencies that ranged from 42 to 100% for adults and 54 to 100% for eggs. LC99 values for the susceptible and the most resistant adults of T. castaneum were 7.4 and 356.9 ppm over 3 d, respectively. LC99 values for T. castaneum eggs were 51.5 and 653.9 ppm, respectively. Based on adult data, the most resistant T. castaneum beetle population was 49× more resistant than the susceptible strain. Phosphine resistance frequencies in P. interpunctella eggs ranged from 4 to 20%. Results show phosphine resistance is present in both species in California. Future research will investigate phosphine resistance over a wider geographic area. In addition, the history of pest management practices in facilities where insects tested in this study originated will be determined in order to develop phosphine resistance management strategies for California almond storage and processing facilities.
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 ( sangautam@ucanr.edu ; george.opit@okstate.edu ).|Current address: Kearney Agricultural Research and Extension Center, 9240 S Riverbend Ave., Parlier, CA 93648.
authors.forename: S G
authors.initials: SG
authors.lastname: Gautam
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078 (sangautam@ucanr.edu; george.opit@okstate.edu).
authors.forename: G P
authors.initials: GP
authors.lastname: Opit
authors.affiliation: Cardinal Professional Products, 57 Matmor Rd., Woodland, CA 95776 (ehosoda@cardinalproproducts.com).
authors.forename: E
authors.initials: E
authors.lastname: Hosoda
mesh_terms: D000818:Animals; D005260:Female; D005651:Fumigation; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D008297:Male; D009036:Moths / Q000187:drug effects* / Q000254:growth & development; D010063:Ovum / Q000187:drug effects / Q000254:growth & development; D010720:Phosphines / Q000494:pharmacology*; D014231:Tribolium / Q000187:drug effects* / Q000254:growth & development
chemical_list: D007306:Insecticides; D010720:Phosphines; C044646:phosphine
keywords: Indian meal moth; phosphine; red flour beetle; resistance management; stored-product