title: Genetics, cross-resistance and mechanism of resistance to spinosad in a field strain of Musca domestica L. (Diptera: Muscidae).
abstract: The house fly, Musca domestica L., is a cosmopolitan insect with the ability to develop resistance to insecticides used for their management. In the present study, we investigated the genetics of spinosad resistance, and cross-resistance potential to other insecticides by selecting a field strain with a commercial spinosad formulation. Bioassays with the field strain, before selection with spinosad, gave resistance ratios (RRs) of 4, 5, 66, 21 and 5 fold for spinosad, indoxacarb, abamectin, imidacloprid and deltamethrin, respectively, in comparison to a laboratory susceptible (Lab-susceptible) strain. After continuous selection of the field strain (Spin-SEL) with spinosad, the RR was increased up to 155 fold; however, the resistance was unstable (RR decreased 1.43 fold) when this strain was not exposed to spinosad for five generations. The Spin-SEL strain did not show cross-resistance to abamectin, indoxacarb or deltamethrin, but showed negative cross-resistance to imidacloprid. Crosses between the Spin-SEL and Lab-susceptible strains revealed an autosomal and incomplete dominant mode of resistance to spinosad. A direct test using a monogenic inheritance model based on Chi-square analysis revealed that the resistance was governed by more than one gene. Moreover, the resistance was neither overcome with the insecticide synergist piperonyl butoxide nor with S,S,S-tributylphosphorotrithioate. Lack of cross-resistance and instability of resistance suggest that rotation with spinosad could be an effective resistance management strategy.
authors.affiliation: Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan. Electronic address: azhar_naturalist@yahoo.com.
authors.forename: Hafiz Azhar Ali
authors.initials: HA
authors.lastname: Khan
authors.affiliation: Department of Entomology, University of Agriculture, Faisalabad, Pakistan.
authors.forename: Waseem
authors.initials: W
authors.lastname: Akram
authors.affiliation: Department of Entomology, Bahauddin Zakariya University, Multan, Pakistan.
authors.forename: Sarfraz Ali
authors.initials: SA
authors.lastname: Shad
mesh_terms: D000818:Animals; D004338:Drug Combinations; D006793:Houseflies / Q000187:drug effects* / Q000235:genetics; D007093:Imidazoles / Q000494:pharmacology; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D007559:Ivermectin / Q000031:analogs & derivatives / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology*; D000073943:Neonicotinoids; D009570:Nitriles / Q000494:pharmacology; D009574:Nitro Compounds / Q000494:pharmacology; D010078:Oxazines / Q000494:pharmacology; D010882:Piperonyl Butoxide / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology
chemical_list: D004338:Drug Combinations; D007093:Imidazoles; D007306:Insecticides; D018942:Macrolides; D000073943:Neonicotinoids; D009570:Nitriles; D009574:Nitro Compounds; D010078:Oxazines; D011722:Pyrethrins; C017180:decamethrin; C082359:imidacloprid; C401104:indoxacarb; C048324:abamectin; D007559:Ivermectin; D010882:Piperonyl Butoxide; C415329:spinosad
keywords: Inheritance; Insecticide resistance; Realized heritability; Resistance mechanism; Selection