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.

No abstract

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.

The walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), has recently invaded Switzerland, Austria, Germany, and France, probably crossing the alpine divide after its initial introduction into Italy. Here, the susceptibility of 36 walnut [Juglans regia L. (Juglandaceae)] cultivars to attack by R. completa was studied in an experimental orchard in Switzerland. Walnut cultivars differed significantly in infestation rates; cultivars that produced large, heavy fruit harboured significantly more larvae than cultivars that produced smaller fruit. Pupal weight was significantly influenced by cultivar, but not by any of the physical properties that we measured. For individual fruit within a cultivar, pupal weight was weakly related to fruit weight and infestation level. Adult longevity was correlated with pupal weight and appeared to be favoured in flies that developed in large‐fruit cultivars. The longevities of adults recovered from different cultivars differed significantly. The shortest longevity was recorded for flies recovered from Geisenheim 1049 (39.2 ± 2.80 days) and the longest for flies recovered from Sheinovo (68.8 ± 21.75 days). Differences in diapause length were also highly significant and varied between 167 ± 5.1 (Esterhazy III) and 257.4 ± 8.21 days (Mayette). These results suggest that (1) across and within cultivars, walnut husk flies prefer to infest (i.e., they develop better in) large, heavy fruit, and (2) offspring that develop in large fruit are likely to accrue fitness advantages over the offspring of females using smaller fruit. Our results provide the basis for subsequent studies on resource defence by males, as they enable a prediction of which type of fruit males should defend more vigorously.