The ecology of Lancetes claussi (M�ller) (Coleoptera, Dytiscidae), the Subantarctic water beetle of South Georgia

Abstract

The development of Lancetes claussi (Muller) is very strongly dependant upon temperature. The Q10 is 3.2–8.1, depending on the larval stage and the temperature. At 10°C the development from the egg to the adult takes an average of 180 days, at 15°C it is 80 days. Due to high mortality, development cannot be successfully completed at 15°C. Larval stage IV has a null point for development of 7.3°C and therefore at 5°C development cannot be completed successfully. The thermal constant for the total development is 380. At the end of the larval development and for pupation L. claussi needs higher temperatures than at the beginning of the larval development. For pupation a fresh weight of 45 mg is necessary. The proportion of dry weight in the fresh weight is clearly age dependant and ranges from about 9 to 28%. Fresh weight increase has an exponential course. The development of L. claussi is discussed with laboratory and field data as an adaptation to the climatic conditions of South Georgia.