Traces of Imidacloprid Induce Hormesis as a Stimulatory Conditioned Response of Sweetpotato Whitefly (Hemiptera: Aleyrodidae).

Our purpose is to determine whether extremely low concentrations of imidacloprid (2-8 ppb) typically found in field soil 1-3 yr after a crop is grown using seed with a standard imidacloprid seed-coating could impact the fitness of whiteflies, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae). Results of our experiments indicate that imidacloprid-resistant whitefly larvae feeding on cotton seedlings growing in soil with 8.0 ppb imidacloprid are conditioned so that when the same individuals feed on plants treated with imidacloprid as adults their fitness, measured as fecundity, increases 30-70% compared with individuals that were not primed as larvae. This conditioning hormesis stimulates resistant whiteflies more than susceptible whiteflies, which may contribute to the selection of resistant populations.

Effects of tail docking on behavior of confined feedlot cattle.

Tail tip injuries occur in some feedlot cattle housed in slatted-floor facilities typically found in the midwestern United States. The practice of tail docking cattle on entry into these feedlot facilities was initiated to prevent tail injuries. Tail docking is a welfare concern from the standpoint that an important method of fly avoidance is removed and the tail docking procedure is painful and often excludes local anesthesia or extended analgesia. The primary objective of this study was to describe the behavioral responses of feedlot cattle following tail docking. Thirty-six heifers were randomly assigned to 1 of 2 treatment groups: docked (DK) or control (CN). All calves received an epidural following surgical preparation of the sacrococcygeal area and postoperative intravenous flunixin meglumine. A portion of the tail of DK calves was removed using pruning shears. An elastrator band was placed near the tail tip for hemostasis and tail tips were sprayed with fly spray. IceQube accelerometers collected step counts, motion index, lying time, lying bouts, and lying bout duration during d -4 through 13. Direct observations of cattle behavior were performed on d 0, 1, and 2. Step counts of DK calves were increased (P < 0.05) on d 0, 2, 3, 4, 6, 9, 10, and 13, and motion index of DK calves was also increased (P < 0.05) on d 0, 3, 4, 9, 10, 11, and 13. Docked cattle performed rear foot stomp behavior more (P < 0.001) than CN on d 0, 1, and 2. Forty-eight hours after tail docking, DK calves had increased lying bouts per hour (1.7 vs. 0.9 on d 0; P < 0.001; 1.1 vs. 0.8 on d 1; P < 0.01) but reduced lying bout durations (12.6 vs. 47.1 min on d 0; P < 0.001; 22.6 vs. 44.7 min on d 1; P < 0.001). On d 0, DK calves twitched tails more (P < 0.05) and ruminated less (P < 0.001). Despite provision of perioperative and postoperative analgesia, we identified altered behavior in DK cattle that may reflect a compromised welfare state for tail-docked feedlot cattle. We recommend that alternative strategies to reduce tail tip injury be explored.