Aulocara elliotti (Orthoptera: Acrididae): Diapause termination, postdiapause development, and prediction of hatch

Abstract

Diapause termination, postdiapause duration, and field hatch of the bigheaded grasshopper, Aulocara elliotti (Thomas), were studied in southwest Montana during a 3-yr period. In general, >70% of the sampled population had completed diapause by mid-November each year. Postdiapause embryonic developmental rates were obtained from a function fitted to hatch versus rime data collected at constant temperatures ranging from 15 to 42°C. The population model design system was used to predict 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 field occurrence of 1st instars, the 50% occurrence dates were very similar (within 2.2 ± 1.1 d for all 5 comparisons). The results of our investigations should enhance the ability of decision support systems for grasshopper management to provide forecasts to land managers and pest advisors.