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Title: Insect phenology : a geographical perspective
Author: Jarvis, Claire H.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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The rate of insect development (phenology) is strongly associated with temperature. Within the biological literature, phenologies are estimated largely on the basis of sparsely located point meterological data. The significance of incorporating a geographical dimension was explored in two application areas where phenologies are used, pest risk assessment (PRA) and integrated pest management (IPM). Colorado beetle (leptinotarsa decemlineata) and codling moth (Cydia pomonella) were used as representative non-indigenous and indigenous test organisms. To ensure relevance to both pest risk assessment and integrated pest management applications, phenology models were run using daily meterological data throughout England and Wales. Interpolation was chosen as an efficient means to create spatial temperature 'surfaces' from distributed daily maximum and minimum temperature data observed at a subset of 174 meteorological stations. Because insect pests are known to be highly sensitive to temperature, considerable attention was paid to minimising the errors generated as part of this process relative to that in previous applied agricultural studies. Comparisons between the commonly used trend surface and inverse distance weighting methods of interpolation were made with partial thin plate splines and ordinary kriging. Unlike earlier work, automatic parameter selection was used to calibrate all the interpolation techniques and care was taken to ensure the comparability of estimated temperature values. Error in estimates by all methods was reduced using a number of guiding topo-climate and land cover covariates. The most favourable estimates of maximum and minimum temperatures throughout the country and over the annual cycle were partial thin plate splines, with daily average r.m.s. accuracies computed using jack-knife cross-validation of 0.8°C and 1.13°C respectively. Partial thin plate splines were also found to be more computationally efficient than both inverse distance weighting and de-trended ordinary kriging. This use of jack-knife cross-validation was assessed using a fully independent data set of a further 100 data points, and was found to be statistically comparable. Providing the interaction between phenology models and sequences of geographically relevant temperature data at this daily step and national coverage necessitated the construction of tailor made research software for the project. The coupled temperature interpolation/phenology modelling system was used to provide a range of outputs to explore the accuracy of predicted phenologies over space and time.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available