Effect of temperature and humidity of sealed brood on chalkbrood development under controlled conditions

Abstract

Summary — 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).

Temperature and chalkbrood development in the alfalfa leafcutting bee, Megachile rotundata

“…apis is similar to A. aggregata in that greater infection rates occur at lower temperatures (25-30°C), or if the larvae are chilled (Bailey, 1967;Flores et al, 1996). Likewise, Rust and Torchio (1992) found a greater prevalence of chalkbrood at lower temperatures for A. torchioi infections in the blue orchard bee (Osmia lignaria propinqua Cresson).…”

“…3). Une réduction similaire du taux de maladie parallè-lement à une augmentation de la température a déjà été notée par d'autres auteurs pour cette abeille (Vandenberg et Goettel, 1995), pour Osmia lignaria propinqua avec A. torchioi (Rust et Torchio, 1992) et pour Apis mellifera avec A. apis (Bailey, 1967 ;Flores et al, 1996). La raison pour laquelle la plus grande probabilité de survenue de cette mycose n'a pas lieu aux températures optimales pour la croissance et la germination d'Ascopharea spp.…”

“…(Vandenberg und Goettel, 1995). Ähnliches gilt bei Befall von Osmia lignaria propinqua mit A. torchioi (Rust und Torchio, 1992) und bei Befall der Honigbiene mit A. apis (Bailey, 1967;Flores et al, 1996). Es ist unklar, warum der höchste Pilzbefall nicht bei den Temperaturen auftritt, die das Optimum für Wachstum und Sporenbildung von Ascosphaera spp.…”

Hygropreference and brood care in the honeybee (Apis mellifera)

“…High humidity would also benefit brood development indirectly since the reproductive success of Varroa parasitic mites decreases with increasing humidity (Kraus and Velthuis, 1997). However, adult honeybee survival has been shown to decrease with increasing humidity (Woodrow, 1935) and the percentage of brood mortality caused by chalkbrood (Ascosphaera apis) was shown to increase by 7% when RH was increased from 68 to 87% (Flores et al, 1996). Unlike ants, honeybees are unable to relocate their brood to the part of the nest most suitable for development.…”

Short communication. Viability and pathogenicity of Ascosphaera apis preserved in integral rice cultures

“…In addition, the development of the disease requires a predisposing condition in the susceptible larva (Heath, 1982). Larvae in the 5 th instar, prior to and some hours after cell capping, are more susceptible to the stress factors that can trigger disease expression (Bayley, 1967;Puerta et al, 1994;Flores et al, 1996). Many factors have been suggested as causes of stress such as excessive moisture, weak colonies, presence of other diseases, inadequate nutrition, excessive colony manipulation (Gilliam, 1990) and chilling of the brood (Bailey, 1967;Flores et al, 1996).…”