Survivor bees: Quantifying environmental stress tolerance in a Southern Californian honeybee population

Bees are key pollinators and important for ecosystem stability and human food production. Considerable declines in several domesticated and wild bee populations have been documented over recent years resulting from climatic and environmental changes, pests, pesticide exposure or loss of genetic diversity as a result of population fragmentation or breeding efforts. These declines are well documented in the honey bee Apis mellifera. More recently, several populations of honey bees have been found to survive and thrive without human management. We study one such population in Southern California which shows remarkable resilience to environmental stressors and is therefore referred to as survivor bees. We compared the health and performance of survivor honey bees in the absence of the usual hive health management. We conducted a 12-month field experiment and compared the performance of managed and survival honeybees. We found that survivor bees were able to suppress Varroa mite infestations and queens survived almost five times longer compared to managed hives. Our findings confirm that naturally selected bee genotypes are capable of dealing with significant environmental stressors. We conclude that these bees could serve as a valuable source to identify and understand underlying molecular mechanisms linked to stress tolerance, which could also be used to select future bee breeding stock.