Postdiapause Development and Prediction of Hatch ofAgeneotettix deorum(Orthoptera: Acrididae)

Abstract

Phenological predictions of life stages of rangeland grasshoppers can be improved with models that predict egg hatch. We investigated the postdiapause development and hatch of the grasshopper Ageneotettix deorum ( Scudder) in the grasslands of southwest Montana during a 3-yr period. Postdiapause embryonic development rates were estimated by exposing eggs to 12 different constant temperature regimes from 9 to 42°C. We used the population model design system to generate a development rate function and to predict hatch at one site in southwestern Montana for 3 yr and at another site in southwestern Montana for 2 yr. When estimated hatch was compared with field occurrence of 1st instars, the 50% occurrence dates were very similar; within 2.0 ± 1.8 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.