Simulation of postdiapause development of the western cherry fruit fly, Rhagoletis indifferens Curran, and its application to predicting the time of adult emergence

Graduation date: 1980Air temperatures and soil temperatures at the surface, two inches,\ud and four inches under a grass cover were recorded over a 93 day period.\ud These data were used along with other temperature data from bare soil\ud in the construction of three sets of models for the prediction of\ud maximum and minimum daily temperatures at several depths below bare\ud and grass-covered soils. The model set having the most accurate\ud predictions was used in conjunction with models for predicting the\ud temperature-dependent postdiapause development of the western cherry\ud fruit fly, Rhagoletis indifferens Curran.\ud Postdiapause developmental rates of R. indifferens pupae collected\ud from Albany, Oregon and Zillah, Washington were determined under constant\ud temperature conditions. Mean times until adult emergence from Albany\ud puparia and Zillah puparia exposed to the same constant temperature\ud were found to be significantly different (α = .01) for all temperatures\ud tested (15.5°C., 19.5°C., and 25.5°C.). Mean times until adult emergence\ud from Zillah puparia held in moist sand at 15.5°C. and in dry sand at\ud 15.5°C. were also found to be significantly different (α = .01). Thus,\ud geographical location and presence or absence of moisture were implicated\ud as factors which may affect the accuracy of the postdiapause development\ud models.\ud Albany puparia were exposed to two alternating temperature regimes\ud to determine if the mean time of adult emergence under alternating\ud temperature conditions can be predicted using constant temperature\ud developmental rate data. The observed mean time of emergence from\ud puparia exposed to a regime with extreme temperature changes was found\ud to be significantly different (α = .01) from the expected mean time of\ud emergence. No significant difference (α = .01) was found between\ud observed and expected mean times of emergence from puparia exposed to\ud the other regime, in which temperatures more closely simulated those\ud found in the field.\ud Albany puparia from which no emergence occurred were dissected to\ud determine the developmental stages of their contents. These data were\ud used in an attempt to determine the upper and lower temperature thresholds\ud for postdiapause development. Thirty degrees C. was established\ud as the upper threshold. A lower threshold was not clearly shown,\ud although the data suggest that it is greater than 6°C.\ud Four models of the postdiapause development of R. indifferens were\ud constructed and evaluated for accuracy of predictions of the times of\ud several levels of adult emergence from an experimental abandoned orchard\ud in Albany, Oregon. The models predict temperature-dependent postdiapause\ud development based on soil temperatures predicted by the soil temperature\ud model set. Three of the models predict postdiapause development on the\ud basis of day-degree relationships. The predictions of the fourth model\ud are based upon a nonlinear temperature-dependent developmental rate\ud function. This model predicted the times of adult emergence with mean\ud errors of ca. two days per year. Thus, it was found to likely be more\ud accurate than other models reported here and elsewhere for the prediction\ud of the times of various levels of emergence of the adult western cherry\ud fruit fly