Changes in behavioral and mortality rates of Apis mellifera in response to early life stress

All organisms experience different kinds of stresses which can impact their health. Correlative evidence suggests that early life stress profoundly influences later life success, but experimental evidence is still rare. Therefore, we designed an experiment to study the effects of early life stress on the later life history of honey bees, Apis mellifera. Honey bees are ecologically important and good biological models due to their abundance and relatively short life span. To test the hypothesis that early life stress affects behavior and life expectancy, we exposed honey bee workers to two economically and ecologically important stressors. We exposed young bees to either a parasitic mite, Varroa destructor, or a commonly used herbicide, paraquat. Individuals were observed daily to quantify effects of stressors on their behavior and lifespan. Additionally, we conducted molecular assays to test for physiological consequences of stress. Behavior and life expectancy were affected by both stressors. Contrary to our hypothesis, we observed a decrease in survival only during the first fifteen days in stressed individuals. Behavior effects were minor. Additionally, there was no significant treatment effect on gene expression patterns and measures of oxidative stress in the adult workers. Together, our results suggest that early life stress effects can persist through metamorphosis into adulthood of honey bees. However, the mortality effects were not long term and other stress outcomes were minor, which might be explained by social protection of the individual.