title: Detection of resistance, cross-resistance, and stability of resistance to new chemistry insecticides in Bemisia tabaci (Homoptera: Aleyrodidae).
abstract: Resistance levels in whitefly, Bemisia tabaci (Gennadius) collections from cotton and sunflower (up to four districts) for five neonicotinoids and two insect growth regulators (IGRs) were investigated for two consecutive years. Based on the LC50(s), all collections showed slight to moderate levels of resistance for the tested insecticides compared with the laboratory susceptible population. The data also indicated that cotton and sunflower collections had similar resistance levels. In comparison (four collections), Vehari collections showed higher resistance for acetamiprid, thiacloprid, and nitenpyram compared with those of others. Average resistance ratios for acetamiprid, thiacloprid, and nitenpyram ranged from 5- to 13-, 4- to 8-, and 9- to 13-fold, respectively. Multan and Vehari collections also exhibited moderate levels (9- to 16-fold) of resistance to buprofezin. Furthermore, toxicity of neonicotinoids against immature stages was equal to that of insect growth regulators. The data also suggested that resistance in the field populations was stable. After selection for four generations with bifenthrin (G1 to G4), resistance to bifenthrin increased to 14-fold compared with the laboratory susceptible population. Selection also increased resistance to fenpropathrin, lambdacyhalothrin, imidacloprid, acetamiprid, and diafenthuron. Cross-resistance and stability of resistance in the field populations is of some concern. Rotation of insecticides having no cross-resistance and targeting the control against immature stages may control the resistant insects, simultaneously reducing the selection pressure imposed.
authors.affiliation: Department of Entomology, University College of Agriculture, Bahauddin Zakariya University Multan, Band Bosan Road, Multan 092, Pakistan. bemisiatabaci75@hotmail.com
authors.forename: Muhammad
authors.initials: M
authors.lastname: Basit
authors.forename: Shafqat
authors.initials: S
authors.lastname: Saeed
authors.forename: Mushtaq Ahmad
authors.initials: MA
authors.lastname: Saleem
authors.forename: Ian
authors.initials: I
authors.lastname: Denholm
authors.forename: Maqbool
authors.initials: M
authors.lastname: Shah
mesh_terms: D000818:Animals; D001681:Biological Assay; D004305:Dose-Response Relationship, Drug; D006430:Hemiptera / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D007605:Juvenile Hormones / Q000494:pharmacology*; D007928:Lethal Dose 50; D009758:Nymph / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010154:Pakistan; D012621:Seasons; D012641:Selection, Genetic
chemical_list: D007306:Insecticides; D007605:Juvenile Hormones