Maternal Age Effects on Embryo Mortality and juvenile Development of Offspring in the Honey Bee (Hymenoptera: Apidae)

To date, no information is available concerning the impact of maternal age on offspring in long-lived social Hymenoptera. We have examined the influence of maternal age on embryo mortality and juvenile growth in offspring in 29 freshly mated (Y0), 29 1-yr-old (Y1), and 18 2-yr-old (Y2) queen honey bees, Apis mellifera L. (Hymenoptera: Apidae). Embryo mortality increased significant with maternal age (Y0 = 9.1%, Y1 = 12.5%, and Y2 = 30.7%). Egg size declined significantly with queen age, did not affect embryo mortality, but did influence embryo size within the egg. (r = 0.54-0.98). Embryo size until hatching, observed under standardized in vitro conditions, was significantly affected by the age of the mother. Maternal age also significantly influenced larval size at an early stage (day 1) but not during later larval growth. Compensatory growth and nonrandom sampling attributable to higher mortality, especially in Y2 offspring, may explain the smaller impact of maternal age in the later larval stage. Embryo mortality was extremely high (55.7%) in the offspring of Y2 queens during the experiments on embryo growth, which required a frequent transfer and observation of the embryos outside the incubator. The stronger response of juvenile stages from older mothers to this manipulation indicates that they are likely to be much more sensitive to stress than offspring from younger mothers.