The effect of temperature on post‐diapause development of the apple sawfly Hoplocampa testudinea Klug was studied under controlled conditions. Survival was found to decrease at temperatures higher than 15 °C, the lethal temperature being close to 25 °C. The lower thermal threshold was 4.5 °C; the values for males and females did not differ significantly. However, different values were established for unprotected individuals, in vermiculite and in potting compost respectively. Based on the overall mean and variance of the developmental time and the overall thermal threshold a simple soil temperature driven phenology model was constructed using a time‐ varying distributed delay. The validation with independent field and semi‐field data revealed the model to be a reliable tool to predict apple sawfly phenology and hence to determine the optimal time for the installation of white sticky traps or for control measures such as insecticide treatments.

The behaviour of adult winter moths Operophtera brumata (L.) (Lep., Geometridae) was investigated during the period of recolonization of fruit orchards in late autumn. Experiments were run simultaneously on both apple and cherry trees in order to detect differences and similarities on these two host plants. The study aimed at a better understanding of spatial and temporal aspects of recolonization of host plants and hence an improvement of monitoring methods.1. Male flight and female migration coincide well enough to guarantee reproductive success. Recolonization of apple and cherry trees occurs simultaneously, but is delayed with decreasing altitude. 2. Male flight activity starts at sunset and reaches its maximum 2 h later. During the night activity decreases gradually to a minimum at sunrise. 3. Females approach tree trunks covering more than 3" of the horizon. The dark part of the horizon appears to be the preferred crawling direction. The travelling time ranges from 1-10 days. 4. Within the tree crown the crawling paths of females are different on cherry and on apple. However, females preferably seek the top segment for oviposition on both cherry and apple trees. 5. On both cherry and apple significantly higher egg densities are found in the top part of the tree crown than in the lower parts. Older wood appears to be more attractive for oviposition probably due to better hiding places. Females seem to optimize between protection and access to food resources for their progeny.The implications of the results for winter moth monitoring in Swiss fruit orchards are discussed.

The forecasting tool SOPRA has been developed with the objective of optimizing timing of monitoring, management and control measures of insect pests in fruit orchards in Switzerland. Applying time‐varying distributed delay approaches, phenology‐models were developed driven by solar radiation, air temperature and soil temperature on hourly basis. Relationships between temperature and stage‐specific development rates for relevant stages of the life cycles were established under controlled laboratory conditions for Dysaphis plantaginea, Hoplocampa testudinea, Cydia pomonella, Grapholita lobarzewskii, Cacopsylla pyri, Rhagoletis cerasi, Anthonomus pomorum and Adoxophyes orana. The implementation of body temperatures in the models is based on habitat selection and biophysical modelling of habitat conditions. In order to validate modelling, phenology predictions were compared with several years of independent field observations. On the basis of local weather data, the age structure of the pest populations is simulated and crucial events for management activities are announced. Through a web interface, the simulation results are made available to consultants and growers (http://www.sopra.info) and the latter can be applied as a decision support system for the eight major insect pests of fruit orchards in the alpine valleys and north of the Alps on local and regional scale.

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The smaller fruit tortrix, Grapholita lobarzewskii Nowicki, has become a major pest in the recent past in apple orchards north of the Alps. Nevertheless little is known about the biology and the behaviour of this species. The effect of temperature on post‐diapause development and survival was studied under controlled conditions in order to establish a basis for the forecasting of adult emergence. Survival was found to be highest at 17 °C and lowest at 11.8 °C. The sex ratio did not differ significantly from 1:1. Based on a linear relationship between temperature and developmental rates, thermal thresholds of 9.6 °C and 9.8 °C were determined for females and males respectively. The thermal constants, i.e., the mean developmental times in physiological time units, were found to be 342 day‐degrees for females and 317 day‐degrees for males, suggesting a slight protandry. Based on the mean and the variance of the developmental times, a simple temperature‐driven phenology model was built using a time‐varying distributed delay. The model was validated by visually comparing the predictions with independent observations on adult emergence, and by calculating the temporal deviations of the predictions. In 4 out of 5 years the mean error was less than 3 days. The model was therefore found to give reliable forecasts of the emergence of G. lobarzewskii and can be used to determine the optimal time for the exposure of pheromone traps, the application of pheromone dispensers for mating disruption, and for the timing of insecticide applications.