Temporal trends in phenology of the honey bee Apis mellifera (L.) and the small white Pieris rapae (L.) in the Iberian Peninsula (1952-2004)

1. The first adult appearance of two insect species, the honey bee Apis mellfera (L.) and the small white Pieris rapae (L.). was examined between 1952 and 2004 in Spain. 2. After factoring out the variability resulting, from the broad geographical and topographical range of the 798 sampling localities. multiple regression models were used to detect temporal trends in phenology. 3. The best models were repeated, including spring temperature as the explanatory variable to examine the effects of climate on appearance phenology. 4. Both species showed similar temporal trends, delaying their appearance phenology until the mid-1970s and advancing it since that time. 5. The appearance times for both species were negatively related to mean temperature between February and April, with both species appearing earlier in years with warmer springs. 6. The strong dependence of appearance dates on temperature indicates that climatic fluctuations are primarily responsible for the inter-annual variability in spring appearance phenology of both species, and consequently account for the observed long-term trends. 7. This study demonstrates that insect phenology is an accurate and sensitive bioindicator of climate change.