Further development of a computer model for simulating pest life cycles

Abstract

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.

From CLIMEX to PESKY, a generic expert system for pest risk assessment1

“…Validation of the CLIMEX projections was provided by later reports (Hurst, 1975;Aitkenhead, 1981;Piekarczyk & Lipa, 1985) in which the beetle was recorded as having spread into most of the area projected by CLIMEX to be suitable. 3) and the emergence and cessation of egg laying of the beetle reported by Baker & Cohen (1985). Further confirmation of the CLIMEX projections was provided by the coincidence of the increase and decline of the weekly growth index, GI, for Cherbourg (Fig.…”

Risk assessment for nonindigenous pests: 1. Mapping the outputs of phenology models to assess the likelihood of establishment

“…Baker & Cohen's (1985) version of PETE, which incorporates development rates derived from degree-day accumulations over base values set for each individual stage, was used in this study. Furthermore, the model has been parameterized and validated both in the laboratory and the field, using data from Normandy where the Colorado beetle is common (Baker & Cohen, 1985). A combination of linear rate temperature relationships are augmented by a sine wave calculation to model intradaily fluctuations, leading to a simple formula for calculating thermal time.…”

“…A combination of linear rate temperature relationships are augmented by a sine wave calculation to model intradaily fluctuations, leading to a simple formula for calculating thermal time. (1978) and Baker & Cohen (1985) for further discussion. Temperature thresholds for ecdysis have also been incorporated.…”

“…Jack-knifing traditionally involves an iterative 'leave-one-out' process where each point in a data set is in turn withheld, the value at the missing point is estimated using the remaining data and the withheld data point is returned to the data set. Then Temperature Sum in column 1 or Parameters for non-linear equation as F5.1 Also enter habitat of stage and temperature used (correction to be implemented later) ****** Function Baker & Cohen (1985) and Welch et al (1978) for further descriptions of terms and algorithms). To construct the results in this paper, a single point was withheld throughout the temporal temperature sequences for both maximum and minimum temperatures.…”

The validation and use of a life‐cycle simulation model for risk assessment of insect pests1

“…Details of the input parameter file were given by Baker & Cohen (1985). The biological input parameters for the simulation program are usually set initially by reference to published data on the effect of temperature on rates of development and activity of the different life stages.…”