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Bees dying before their time

Worker bee carrying pollen

Muhammad Mahdi Karim / Wikimedia Commons

Western honey bees (Apis mellifera) are dying earlier. Experiments carried out by a team led by Dennis van Engelsdorp, an entomologist from the University of Maryland, USA, indicate that they now live about half as long as they did 50 years ago. The researchers removed pupae (immature forms of the insect) from hives and raised them in a lab. The bees died after an average of 18 days. In the 1970s, they lived for 34 days, on average. To understand the relationship between the lifespan of each individual bee and the success of the colony, the scientists used a mathematical model that simulates this reduced life expectancy for every individual in the group. They observed that a 50% decrease in worker lifespan would lead to a 33% decline in hive size per year, similar to real-life observations by beekeepers (Scientific Reports, November 14). In an interview with the magazine New Scientist, biologist Anthony Nearman, coauthor of the study, theorized that genetic factors may be behind the reduction in hives and not just insecticides. By selecting colonies to become resistant to disease, breeders may have inadvertently shortened bee lifespans.