Predicting spring oviposition by raspberry cane midge from accumulated derived soil temperatures

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Abstract
Summary: An accumulated soil temperature model is described which calculates the first oviposition date for overwintered populations of the raspberry cane midge (Resseliella theobaldi). The model uses values for mean 10 cm soil temperature, derived from daily maximum and minimum air temperatures and 10 cm soil temperature at 0900 GMT. It was developed by minimising the variation between observed dates for the start of oviposition over an 8‐yr period and accumulated air or soil temperature, using a series of base temperatures. The best fit was obtained with soil temperatures accumulated above a base temperature of 4°C. Oviposition was predicted to start when the daily accumulated soil temperature reached 339°C days above a base temperature of 4°C.Field observations and model predictions suggested that emergence and oviposition dates were influenced by the direction of the slope of raspberry plantations. To compensate for this, an empirical correction has been incorporated into the model to advance or retard the predicted oviposition date by adjusting the estimated maximum soil temperature to allow for aspect. The geographical variation between dates for first oviposition was simulated by running the model for nine meteorological sites in the UK in 1985 and 1986.