EFFECTS OF EARLY DEVELOPMENTAL STRESS ON HONEY BEES

The proposed project is directly aligned with the FY 2016 Foundational Program Area "Plant health and production and plant products" and the FY 2016 Challenge Area, "Agricultural Science for Climate Variability and Change." Pollinator health is critical to many plant production systems and investigating stress-compromised honey bees will provide new insights in sub-lethal effects that contribute to wide-spread pollinator declines. Heat is relevant as potential Varroa treatment and as stressor of many pollinators due to climate change.The 2006 honeybee health crisis began a large scientific movement to identify and characterize its potential contributors. No single causal factor has been identified despite considerable scientific effort across the years. However, important stressors have been identified and better understanding of honeybee pathogen-host dynamics has been achieved. A variety of acute stressors have been shown to negatively influence honeybee mortality and longevity at high dosages. However, the potential long-term and persistent effects of their sub-lethal dosages are often disregarded. Embryonic and post-embryonic developments are crucial phases during which acute stressors may cause irreversible damages to the individual. Honeybee development from egg to 5th larval instar requires constant worker care. Yet despite the high degree of social immunity, larvae have been shown to be the most susceptible to acute pesticide exposure. Furthermore, an overrepresentation on worker-stress studies exists undermining stress response in drones and queens. Stress responses are though to be identical across all honeybee castes. This overgeneralization is unfeasible particularly in view of the queen's unique cellular compositions, gene expressions and behavior. A developmental biased also exists as stress responses are often characterized at the adult stage despite evidence of up to 50 times sensitivity in early developmental stages. The proposed study will scrutinize acute stress responses in the honeybee system using a systematic approach. Objective 1 will assess the persistent molecular impacts of acute heat exposure of promising honeybee stressors applied during a critical transitional developmental stage, the 5th instar. Objective 2 will assess the temporal dynamics of a candidate's stress response. Candidate stressor will be applied in three additional developmental stages: 3rd instar, white-eyed pupae, and dark-eyed pupae. Objective 3 will challenge the overgeneralization of stress response by investigating caste-specific responses. Caste sensitivity to the candidate stressor and its stress response will be assessed as described in previous objectives. This proposal will systematically investigate a commonly studied paradigm (honeybee stress response) through an understudied perspective (stage and caste sensitivity). It will address the question of whether early developmental acute stressors induce long-term consequences after metamorphosis. It will attempt to standardize the concept of stress across the honeybee caste system and provide details in lieu of generalizations. The proposed research could potentially establish caste specificity in stress responses. Additionally, this study will explore the highly specialized drones that have been disregarded outside of the realm of honeybee mating biology and physiology.