Bee colony health indicators: synthesis and future directions.

Abstract The western honey bee Apis melifera plays an important role in human well-being by producing honey, sustaining populations of wild plants and supporting human-dependant crop production. Unfortunately, abnormal high-mortality rates of colonies have been revealed all over the world. This paper reviews the stress factors that are likely involved in the cause of honey bee poor health, the mechanisms underlying bee health and survival and the different early warning indicators of bee colony mortality. Honey bee colonies can be assimilated to a complex system for which survival depends on its individual quality, its adaptive capacity and its threshold of resilience to pressures. Many stress factors are likely involved, by interaction, in the cause of honey bee colony mortality. Three main groups of stressors are highlighted to affect the colony survival, including (i) environmental pressures such as lack of flowers and pesticide exposure, (ii) biotic pressures such as parasites and pathogens and (iii) beekeeping management such as the use of chemical treatments. Routine monitoring of colonies provides robust approaches to assess the health status of honey bees. By tracking specific colony parameters such as queen performance, colony dynamics, in-hive products and the prevalence of pathogens, beekeepers can establish a health status of the colony. By comparing this field-based health status with model-based predictions, a new area is emerging towards the detection of early warning indicators of colony mortality.