Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/1999
Publication Date: N/A
Interpretive Summary: A study was made of the developmental rate of eggs of the white whiskered grasshopper, a pest of Western grasslands. Mathemathical models derived from these studies were iterated with sub-surface soil temperatures that had been recorded where these pests occurred. We also monitored the occurrence of hatchling white whiskered grasshoppers daily at the same areas in the spring for three years. We found our models to produce a prediction of hatchling occurrence to be very similar to that of the actual occcurrence of hatchlings. The results of these studies should enhance the ability of decision support systems for grasshopper management to provide accurate grasshopper occurrence forecasts to land managers and pest advisors, particulary, those that are called upon to provide protection against these pests on Federal lands (i.e. USDA-APHIS, USDA-USFS, USDI-BLM).
Technical Abstract: Postdiapause development and hatch of the white whiskered grasshopper, Ageneotettix deorum (Scudder) were studied in the grasslands of southwest Montana during a 3 yr. period. Postdiapause embryonic development rates were estimated by exposing eggs to 12 different developmental temperatures from a range of 9 degrees-C to 42 degrees-C. We then used the population model design system (PMDS) to generate a development rate function and to predict hatch at 2 sites in southwestern Montana for 3 yr. Field emergence (1st instars) was monitored by taking sweep net samples and used to assess the accuracy of the predictions. When estimated hatch was compared with field occurrence of 1st instars, the 50% occurrence dates were very similar; within 2.6 +/- 1.4 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.