Temperature profiles of the brood nests of Apis cerana and Apis mellifera colonies and their relation to varroosis

SUMMARYTemperatures in the brood nests of Apis mellifera mellifera and Apis cerana indica were compared. Within the centre we found similar temperatures in worker brood cells, at external temperatures between 18°-33°C. At the periphery of the brood nest, where drone brood usually is located, temperature in brood cells of A. cerana was clearly lower compared to A. mellifera. Average temperature in drone brood cells was 0.4°C lower compared to nearby worker brood cells. While temperature in worker brood cells of A. mellifera colonies was close to 35°C, temperature in drone brood cells of A. cerana colonies was only 33°C, at ambient temperatures in Sabah (Malaysian Borneo). On its original host A. cerana, the parasite Varroa jacobsoni reproduces nearly exclusively in capped drone brood cells. This explains why the parasite has its reproductive optimum at 33°C. ‘Temperature jumps’, discussed in previous publications as a mechanism by which A. cerana colonies could defend themselves against varroa infestations, were found to be artifacts caused by reactions of the bees to the temperature measurement device.