Phenology of Three Coccinellid Species:12 Thermal Requirements for Development

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Abstract
Three coccinellids, Adalia bipunctata L., Coccinella transversoguttata Brown, and Coccinella septempunctata L., show optimal preimaginal development and survival at temperatures between 26.7° and 29.4°C. Development of A. bipunctata, from oviposition to adult emergence, requires an accumulation of 263 heat degree days (K) above a theoretical threshold for development (t) of 9.0°C. Coccinella transversoguttata requires 218 heat degree days above 12.2°C. and C. septempunctata, an imported Palearctic species, requires an accumulated K value of 197 above 12.1°C. Adalia bipunctata's low t value allows early-season development, when temperatures are low. In comparison C. transversoguttata and C. septempunctata can develop faster at higher summer temperatures because of their low K values. Based solely on thermal characteristics, the three coccinellid species may produce between 3 and 4 generations per year. However, the species differ in the degree to which they approach the maximum developmental rate in the field. These differences are determined by the species' differential prey specificity and diapause characteristics.