Bedded vs. flat-planted alfalfa:  Comparative results of three sampling techniques for alfalfa weevils (Hypera postica). 

Three sampling techniques (numbers per stem, per 180 degree sweep and per pendulum sweep) were conducted to determine alfalfa weevil larvae numbers from replicated plots from both flat planted and bed planted alfalfa. Comparative data were needed as alfalfa grown on beds caused difficulty with 180 degree sweep methods, affecting shoulders and elbows. While numbers of weevils per stem were very similar (0.75+0.4), large differences were noted for numbers of alfalfa weevils between pendulum vs. 180 degree sweep techniques for both bedded and alfalfa planted on flat ground. More alfalfa weevil larvae were collected using pendulum sweeps in from both field types, as initial ratios of collected weevil larvae from untreated alfalfa was approximately 3.72:1 from flat field alfalfa vs. ~2.1:1 from bedded alfalfa. These comparative ratios changed over time as alfalfa weevil populations increased/decreased, and were also altered by insecticide mode of action.