Effects of queen mating status, pre-diapause weight and pupae’s sex on colony initiation in small-scale rearing of Bombus terrestris

Abstract

Diapause control and colony initiation are among the major problems encountered in the rearing of bumble bee colonies in small-scale rearing. In this study, we used Bombus terrestris queens obtained from commercial colonies to investigate (1) the diapause survival in virgin and mated queens, (2) the diapause and colony initiation performance of mated bumble bee queens in relation to the pre-diapause weight and (3) the effect of pupae's sex on colony initiation. We found that diapause survival is negatively affected by mating and by the low pre-diapause weight, but first egg deposition and development of the first adult worker were delayed in heavy queens. We found no significant differences in the egg-laying success in relation to pupae's sex; however, queens stimulated with queen pupae laid more eggs per cell and developed a first brood larger than those stimulated with male pupae. Our results can be useful in small-scale rearing, including the rearing of wild queens for conservation purposes.bumble bee / colony initiation / egg laying / experimental rearing / diapause

The effect of intrinsic physiological traits on diapause survival and their underlying mechanisms in an annual bee speciesBombus impatiens

“…However, these queens varied in their age, which may explain the inconclusive results. Similar findings were demonstrated in previous studies ( Bogo et al ., 2017 , Holm, 1972 , Owen, 1988 ), all showing that heavier queens survived longer diapause in several bumble bee species; however, these studies all used weight categories and/or queens of an unknown age. Bumble bee distribution across higher latitudes and altitudes makes them crucial pollinators in alpine ecosystems and for numerous rare plants species, and their ability to buzz-pollinate makes them effective pollinators in many agricultural systems ( Morandin et al , 2001 , Pleasants, 1980 , Velthuis et al , 2006 ).…”

“…Additionally, we found mass to be a positive predictor of diapause survival, with heavier queens surviving longer periods of time. Previous studies in bumble bees, which examined the effect of pre-diapause mass on diapause survival, found no correlation between body mass and the length of survival excluding a threshold under which queens are unlikely to survive diapause ( Beekman et al ., 1998 , Vesterlund et al , 2014 ), used limited categorical data or did not control for queens age ( Bogo et al ., 2017 , Gosterit et al ., 2009 , Holm, 1972 , Owen, 1988 ). These studies looked at survival at a predetermined timepoint, unlike our study where survival was monitored continuously on a weekly basis until all queens died for a period equivalent to natural diapause.…”

“…Survival of diapause is often linked with higher body mass and thus increased nutritional stores ( Beekman et al , 1998 , Bogo et al , 2017 , Roberts et al , 2004 ). Nutrients are likely acquired in the days following eclosion ( Woodard et al , 2019 ), but detailed empirical data on this time period is limited to a few studies in a limited number of species ( Alford, 1969a , Roseler et al , 1986 ).…”

The Importance of Males to Bumble Bee (Bombus Species) Nest Development and Colony Viability

“…Two studies have examined the effect of mating on survival and longevity. Virgin queens have been found to be significantly more likely to survive compared to their non-virgin counterparts [110], and virgin queens have been found to have increased longevity [111]. However, the effect was minor, and it is unclear whether a small difference in longevity constitutes a biologically significant difference.…”

No evidence for an inbreeding avoidance system in the bumble bee Bombus terrestris

“…Second-generation laboratory colonies of B . terrestris (n = 25) were reared from commercial colonies (Bioplanet srl, Cesena, Italia) following Bogo et al (2017). Subsequently, during the phase of male and gyne production, the obtained colonies were maintained at 25 ± 1°C and 60 ± 10% relative humidity (RH), in continuous darkness, and fed ad libitum with fresh frozen pollen and sugar syrup.…”