This thesis aimed to develop an environmentally friendly approach to manage the pea pest Cydia nig-ricana Fabricius (Lepidoptera: Tortricidae) by assessing spatial and temporal infestation risk factors. Data on pea moth abundance, pea phenology, and seed damage was collected from various pea fields in northern Hesse during 2016-2019. Flowering time, first pea moth arrival in pheromone traps and the proximity to previously cultivated pea fields were identified as key factors of infestation risk. A general additive model including these factors discriminated between low and high infestation fields with an accuracy rate of 95%. This model can be used to support informed management decisions, such as implementing preventive measures or selective pesticide use. To reduce monitoring efforts required for model application, field emergence patterns of C. nigricana were modelled as a function of cumulative development rate to determine the optimal start date for placing pheromone traps. The effects of seven constant temperatures and five photoperiods on the development rate (DR) were assessed in climate chambers. In contrast to the temperature, photoper-iod had no significant effect on DR. The four-parameter Brière model best described climate chamber data and was subsequently applied to the interpolated field air temperatures from 36 pea moth emer-gence sites. The three-parameter Gompertz model was the best-fit option for cumulative field devel-opment rate relative to the cumulative field emergence. Model performance was validated using an independent field dataset, predicting first trap capture and peak emergence of male moths with a mean deviation of two days. Thermal performance of field-collected insects differed between 2019 and 2020 for C. nigricana and its main parasitoid A. quadridentata, respectively. Post-diapause devel-opment seems to be highly synchronized between the two species, leading to simultaneous field emer-gence. However, differences in survival rates at high temperatures above 32°C could impact future parasitisation and should be further investigated. To identify factors contributing to the variation in temperature response in climate chambers for C. nigricana, larval collection date, host pea variety, the number of sampled pea fields and artificial overwintering were examined. None significantly affected emergence time. Further, artificially overwintered larvae from the same cohort showed no shift in thermal performance when placed in soil and left to emerge under natural field conditions. The ob-served differences may therefore be related to climate chamber conditions, such as fungal infection or a difference between diapause-terminating processes between climate chamber and field condi-tions. This underscores the importance of multi-year experiments to enhance prediction reliability and address challenges associated with field-derived insect materials. Furthermore, additional research is needed to explore potential interactions between C. nigricana emergence and the time spent under diapause-maintaining conditions.
Natalia Riemer (Wed,) studied this question.