Laboratory and Field Investigations of the Effect of Temperature on the Development of Neodiprion sertifer (Geoff.) in the Cocoon

Abstract

AbstractLaboratory studies show that diapause, or eonymphal development, has a temperature optimum approximating 8 °C, at which some 29 days are required for its completion. The optimum for morphogenesis is 22 °C. About 33 and 37 days for females and males, respectively, are required for its completion.Field data for three sites with mean temperatures near 22, 19, and 16 °C. show that emergence took place earliest at the intermediate site and latest at the exposed site, which experienced the highest mean temperature. Emergence of males and females overlapped, but at the shaded site, having the lowest mean temperature, females emerged sooner than males, whereas the reverse was observed at the exposed site.The length of the eonymphal stage in the field is dependent upon site temperature and can be predicted from laboratory data. The duration of the pronymphal stage is dependent not only upon site temperature, but also upon the length of time which has been required for eonymphal development. Thus the longer the eonymphal period. the shorter the pronymphal period. This compensatory mechanism is probably due to a temperature effect on any morphogenesis that takes place concurrently with diapause.