title: Resistance and cross-resistance to neonicotinoid insecticides and spinosad in the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae).
abstract: The Colorado potato beetle, Leptinotarsa decemlineata (Say), has developed resistance to many insecticides used for its control, recently including imidacloprid, a neonicotinoid compound. Other neonicotinoids are now being deployed to control this pest. A key point in the strategies of resistance management is the monitoring of resistance and cross-resistance. In the summer of 2003, imidacloprid-resistant adult Colorado potato beetles collected from Long Island, New York, USA were bioassayed using topical applications of imidacloprid and nine other neonicotinoids. Compared to a standard susceptible strain, the Long Island beetles showed 309-fold resistance to imidacloprid, and lower levels of cross-resistance to all other neonicotinoids, despite these never having been used in the field, i.e., 59-fold to dinotefuran, 33-fold to clothianidin, 29-fold to acetamiprid, 28-fold to N-methylimidacloprid, 25-fold to thiacloprid, 15-fold to thiamethoxam, 10-fold to nitenpyram, but less than 2-fold to nicotine. In injection bioassays, high resistance to imidacloprid was also found (116-fold). Piperonyl butoxide partially suppressed resistance to imidacloprid, but the resistance level was still over 100-fold, indicating that other mechanisms were primarily responsible for resistance. Low levels of resistance (8- to 10-fold) were found to the nicotinic activator, spinosad, in an imidacloprid-resistant strain collected from the same field in 2004. The cross-resistance seen with all the neonicotinoids tested suggests that the rotation of imidacloprid with other neonicotinoids may not be an effective long-term resistance management strategy. Rotation with spinosad also carries some risk, but it is unlikely that spinosad resistance in this case is mechanistically related to that for the neonicotinoids.
authors.affiliation: Department of Entomology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: David
authors.initials: D
authors.lastname: Mota-Sanchez
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hollingworth
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Grafius
authors.forename: Dale D
authors.initials: DD
authors.lastname: Moyer
mesh_terms: D000691:Anabasine; D000818:Animals; D001517:Coleoptera; D004338:Drug Combinations; D007093:Imidazoles; D007305:Insecticide Resistance; D007306:Insecticides; D007928:Lethal Dose 50; D018942:Macrolides; D000073943:Neonicotinoids; D009538:Nicotine; D009574:Nitro Compounds
chemical_list: D004338:Drug Combinations; D007093:Imidazoles; D007306:Insecticides; D018942:Macrolides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid; D009538:Nicotine; D000691:Anabasine; C415329:spinosad