title: Imidacloprid as a contact arrestant for larvae of the European chafer, Amphimallon majale.
abstract: BACKGROUND
  Manipulative studies of the behavioral response of soil-dwelling insects to insecticides and other antagonists are stymied by the difficulties of observing and interpreting interactions played out below ground. Six experiments were carried out using X-ray radiography to quantify the movement of the European chafer, Amphimallon majale (Razoumowsky), larvae in response to imidacloprid and how this was affected by host plant cues and cold temperature.
  
  
  RESULTS
  The movement of third instars was arrested in imidacloprid-treated soil at ≥ 0.6 ppm concentration. At ≥ 0.8 ppm, the arrestant effect of imidacloprid was stronger than the attraction cue posed by germinating grass seed. There was a less disruptive effect on dispersal distance in vertical versus lateral panels. In vertical panels, there was a less disruptive effect on downward movement under a cold temperature treatment that simulated overwintering conditions.
  
  
  CONCLUSIONS
  Larvae of A. majale do not remotely detect imidacloprid in the soil; they neither evade contact, nor are repelled after contact. Imidacloprid thereby acts as a contact arrestant to disrupt grub movement. This finding might help to explain the synergistic effect of imidacloprid in combination with other biological agents for white grub control, and its effects on grub overwintering behavior.
authors.affiliation: College of Environmental Science and Engineering, Nankai University, Tianjin, China. gengpingzhu@hotmail.com
authors.forename: Gengping
authors.initials: G
authors.lastname: Zhu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Petersen
authors.forename: Guoqing
authors.initials: G
authors.lastname: Liu
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Peck
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003080:Cold Temperature; D001517:Coleoptera / Q000187:drug effects*; D007093:Imidazoles / Q000633:toxicity*; D007302:Insect Repellents / Q000032:analysis*; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000633:toxicity*; D006109:Poaceae; D011859:Radiography
chemical_list: D007093:Imidazoles; D007302:Insect Repellents; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid