AULOCARA ELLIOTTI (ORTHOPTERA, ACRIDIDAE) - DIAPAUSE TERMINATION, POSTDIAPAUSE DEVELOPMENT, AND PREDICTION OF HATCH

Diapause termination, postdiapause duration, and field hatch of the bi gheaded grasshopper, Aulocara elliotti (Thomas), were studied in south west Montana during a 3-yr period. In general, >70% of the sampled pop ulation had completed diapause by mid-November each year. Postdiapause embryonic developmental rates were obtained from a function fitted to hatch versus time data collected at constant temperatures ranging fro m 15 to 42 degrees C. The population model design system was used to p redict hatch at 2 sites in southwestern Montana for 3 yr. First-instar occurrence was monitored by sweep net samples and used to assess the accuracy of the predictions. When simulated hatch was compared with he ld occurrence of Ist instars, the 50% occurrence dates were very simil ar (within 2.2 +/- 1.1 d for all 5 comparisons). The results of our in vestigations should enhance the ability of decision support systems fo r grasshopper management to provide forecasts to land managers and pes t advisors.