Effect of temperature and humidity of sealed brood on chalkbrood development under controlled conditionsJ.M. Flores, J.A. Ruiz, J.M. Ruz, F. Puerta, M. Bustos, F. Padilla and F. Campano
Departamento de Biología Animal, Sección de Biología Aplicada, Facultad de Veterinaria, 14005 Córdoba, Spain
Abstract - This paper reports improvements on a previous technique of ours for producing chalkbrood disease in Apis mellifera under controlled conditions. Mummification reached almost 95% (the previous technique reached 70%) when fifth instar larvae were chilled at 18 °C 24 h before sealing and kept at 25 °C for 6 days after operculation. When the larvae were chilled, but the temperature after operculation was 30 or 35 °C, mummification reached 43.65 and 29%, respectively. Percentages of mummification were lower when chilling prior to sealing cells was not applied: 77.62% (at 25 °C after sealing), 15.31 % (at 30 °C) and 2.22% (at 35 °C). The effect of a high relative humidity (rh) (87%) combined with slight chilling (30 °C) induced a higher percentage of mummification (7.75%) then compared to the same temperature but lower rh (only 0.95% of larvae were mummified at 68% rh).
Key words: Apis mellifera / chalkbrood / Ascosphaera apis / brood chilling / humidity