Pupae of Rhagoletis cerasi (L.) from Austria, Czechoslovakia, Switzerland and Italy were stored at 4° for 155 days and then transferred to eleven constant and four cycling temperature regimes until the flies emerged. No flies emerged in 324 days at 8° constant but mean emergence was 84% for the remaining regimes. Female flies emerged slightly earlier than males and flies from Italy were the last to start emerging. Reduced to a common mean base temperature of 6.8°, temperature sums in day degrees C to 10% emergence of female flies were 331 (Austria), 319 (Czechoslovakia), 359 (Italy) and 321 (Switzerland). The equivalent sums are also given for first, 50% and 90% emergence. When tested with soil temperature data from Switzerland 321 day degrees above 6.8° and 430 day degrees above 5° gave effectively the same estimates for practical forecasting purposes. ZUSAMMENFASSUNG TEMPERATUREINFLUSS AUF DIE NACHDIAPAUSEENTWICKLUNG VON VIER GEOGRAPHISCHEN HERKÜNFTEN DER KIRSCHENFLIEGE (RHAGOLETIS CERASI) Puppen von Rhagoletis cerasi L. aus Österreich, der Slovakei, der Schweiz und aus Italien, welche aus infizierten Kirschen gewonnen worden waren, wurden während 155 Tagen bei 4° gelagert und anschliessend für die Weiterentwicklung in 11 konstanten und 4 fluktuierenden Temperaturregimen untersucht. Keine Fliegen schlüpften nach 324 Tagen Inkubationsdauer bei 8°, während die durchschnittliche Schlüpfrate bei den übrigen Temperaturbedingungen 84% betrug. Die beobachteten und berechneten Werte für die Entwicklungsdauer bis zur Erreichung der Schlüpfraten von 10% und 50% sind nach Geschlechtern und Herkünften getrennt in Tabellen aufgeführt. Lineare Regressionsgleichungen wurden berechnet für die Kurven der Entwicklungsraten und verwendet für die Berechnung der Entwicklungsnullpunkte und effektiven Temperatursummen. Weibliche Fliegen schlüpften früher als Männchen und Puppen aus Italien entwickelten sich von allen vier Herkünften am langsamsten. Berechnet auf der Basis eines durchschnittlichen Entwicklungsnullpunktes von 6.8° als Schwellenwert benötigten die Weibchen der verschiedenen Herkünfte bis zum Erreichen der Schlüpfrate von 10% folgende Temperatursummen in Gradtagen: Österreich 331°, Slovakei 319°, Italien 359° und die Schweiz 321.Die entsprechenden Werte für das Erreichen des Zeitpunktes von Schlüpfbeginn, 50% und 90% Schlüpfrate sind ebenfalls in Tabellenform dargestellt. Der normalerweise für Prognosezwecke verwendete Schwellenwert von 5° wurde zu Vergleichszwecken ebenfalls in die Analyse der experimentellen Daten einbezogen, doch zeigte es sich, dass er zu tief liegt. Die Uberprüfung der Prognosemethode in der Schweiz mittels Bodentemperaturen in 5 cm Bodentiefe unter Anwendung des neuen Schwellenwertes von 6.8° und der effektiven Temperatursumme von 321 Gradtagen führte jedoch zu den gleichen Schlussfolgerungen wie die Verwendung des traditionellen Schwellenwertes von 5° und der Summe von 430 Gradtagen. Da die Berechnungen auf der Basis von 5° einfacher sind und gute Übereinstimmung mit den Fangresultaten im Freila...
Sources of error in using accumulated temperatures for estimating the timing of events in insect life cycles, such as adult emergence and egg hatching, have rarely been examined in detail. There are two sources of error, one in the calculations, the other in the observations. Errors in the calculations arise from using the wrong base temperature, from using the daily arithmetic mean temperature in the calculation of the daily effective temperature on occasions when the mean is not appropriate and, occasionally, in using the linear relationship between temperature and growth where a non‐linear relationship would be more appropriate. Errors in observations arise mainly from attempts to employ standard meteorological measurements rather than measurements made from sites where the insects normally live. Temperature measurements in the soil at different depths on the flat and on north and south slopes, on the bark of trees and on the leaves of plants have been converted into estimates of insect development to demonstrate the effect of local differences in microclimate. It is strongly emphasized that day‐degrees as units of effective temperature in temperature summation calculations are physiological units of growth and not physical units of heat energy input. Les sources d'erreurs résultant de L'utilisation de la somme des températures pour prévoir le déroulement des cycles évolutifs des insectes (éclosion des adultes, ceufs, etc.) n'ont guère étéétudiées de rnanière approfondie. De L'avis de L'auteur, ces erreurs peuvent provenir de I'observation et du calcul. En ce qui concerne ce dernier, L'utilisation dune fausse température de base, résultant du recours à une moyenne arithmétique de la température quotidienne établie à tort, est préjudiciable. D'autre part, le résultat peut être faussé lorsqu'il est recouru à une relation linéaire entre la temperature et la croissance alors qu'il serait préferable de tenir compte d'une relation non linéaire. Les erreurs d'observation concernent principalement L'utilisation de données météorologiques à caracère général, au lieu de se référer à celles qui prévalent au site même où se trouve L'insecte. La détermination de la temperature du sol à des profondeurs différentes, sur terrain plat ou incline vers le nord ou le sud, ainsi que de la température de l'écorce des arbres ou des feuilles des plantes rvele L'influence du microclimat sur le développement des insectes. Il est souligné que le degre‐jour, utilisé dans les calculs de sommes de témperatures, est une unite physiologique de croissance et non une unité physique dabsorption d'énergie thermique.
The development of all stages of Spodoptera littoralis (Boisd.) was studied in controlled-environment cabinets under a range of constant and cycling temperatures. Larvae were tested on three food plants; development was faster on lucerne than on two cultivars of chrysanthemum, Taffeta and Fred Shoesmith. The durations of each instar were similar in relation to larval life span, but at low temperatures and on chrysanthemum many larvae went through an extra instar. Late-instar larvae were nocturnal but larval development was little disturbed by a night-break lighting regime as used in the production of all-the-year-round (AYR) chrysanthemums, and only slightly more so by a reversed temperature cycle. The latter changed the daily pattern of moth emergence which otherwise occurred mostly when temperatures were highest or in the dark. The development results were used to estimate duration of development by summing (a) daily increments of development (100/duration of development), (b) day-degrees (for eggs 28·6 day°C above 14·8°C; for larvae on lucerne 266·1 day°C above 11·5°C, on chrysanthemum 257·1 day°C above 13°C, and above 13°C 177·1 day°C for male pupae and 153·5 day°C for female pupae). The estimates were compared with observed development times for all stages in an environment where temperatures fluctuated naturally. Both methods gave satisfactory estimates when development times were short, but temperature summation was less accurate when maximum temperatures fell close to base temperatures. It is concluded that summation of development increments would give a more consistently accurate account of the life-cycle of S. littoralis on AYR chrysanthemum under glass to enable development to be predicted or past events in the life-cycle to be dated. Tables of development increments against daily maximum and minimum temperatures are given for each stage. To estimate duration of development from these Tables, the daily percentage development corresponding to each day's maximum and minimum temperature is summed up to 100%. This gives an estimate of the median point of hatching or pupation.
Modifications to the PETE computer model developed at the University of Michigan, USA are described. These include: routines to allow use of non‐linear relationships between temperature and rate of development or progress of diapause, as alternatives to temperature sums; thresholds for ecdysis to mimic synchronisation observed in natural populations; adult activity levels and oviposition optionally controlled by temperature, sunshine and rainfall; calculation of day length and temperature at the time of the daily peak of adult activity; obligatory diapause; photoperiodic induction of facultative diapause and preliminary ideas on simulation of microclimate. Validation is discussed particularly in relation to simulating the life cycle of the Colorado beetle. Les modifications apportées au modèle informatique PETE, mis au point à l'Université du Michigan (USA), sont décriles. Elles comprennent: 1) des méthodes pour utiliser des relations non linéaires entre la température et le taux de croissance ou le cours de la diapause plutôt que les sommes de températures; 2) des seuils pour l'ecdysis entraînant une synchronisation observée dans des populations naturelles; 3) les niveaux d'activité des adultes et l'oviposition éventuellement contrôlés par la température, l'ensoleillement et les précipitations; 4) le calcul de la longueur du jour et de la température au moment du pic journalier d'activité des adultes; 5) la diapause obligatoire; 6) l'induction photopériodique d'une diapause facultative et des éléments préliminaires sur la simulation du microclimat. La valeur du modèle est discutée, en particulier dans le cas de la simulation du cycle biologique du doryphore.
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