In today’s Academic Minute, Dr. Reinhard Stöger of the University of Nottingham reveals how pesticides can alter the DNA and behavior of honeybees.
Reinhard Stöger is an associate professor of epigenetics at the University of Nottingham. His current research is examining the role epigenetic mechanisms play in modulating gene-environment and developmental processes while identifying genomic locations that are responsive to environmental stressors and human-produced compounds. He earned his Ph.D. at the Research Institute of Molecular Pathology in Vienna.
Dr. Reinhard Stöger – Pesticides and Bee Behavior
Members of a honeybee colony depend on food that is collected from the land surrounding the hive. The queen, drones, young workers and developing brood: they all feed on pollen and nectar collected by foraging worker bees. If pesticides have been applied to protect crops in surrounding fields, pollen and nectar of plants growing in and close to those fields can become tainted with such synthetic compounds. It has been suggested that foraging bees may expose entire hives to pesticides by importing pesticide-tainted nectar and pollen. As a result the health of a whole honeybee colony could become compromised. Is there any basis for such concerns? Can exposure to such low levels of an insecticide really be harmful for bees?
We were interested to test the impacts of pesticides on bees and decided to have a closer look at the insecticide imidacloprid. Imidacloprid belongs to a chemical class of crop-protecting agents called neo-nicotinoids. These neonicotinoids are used worldwide in order to protect many varieties of crops including canola, soybeans and maize against pests such as aphids, whiteflies and weevils.
This was our experiment: We provided syrup tainted with low levels of the imidacloprid pesticide, to three honeybee colonies with freely foraging worker bees. The amount of pesticide in the syrup was similar to that detected in nectar and pollen of imidacloprid-treated crops. As a control, we supplied three hives with un-tainted syrup. After two weeks of feeding syrup, we collected worker bee larvae from all hives and analysed the activity of their genes. What we found is that 300 genes behave somewhat differently if we compare larvae from insecticide-exposed and non-exposed hives. Remarkably, many of these 300 genes play a role in metabolism, regulating the way cells process and use energy. The amount of individual types of fat molecules also appears to be altered in larvae collected from hives that were fed imidacloprid-tainted syrup.
We conclude that low levels of insecticide – if imported into hives via nectar and pollen could indeed influence gene function and metabolism of honeybee larvae. As is typical for science: our results open up many new questions: do low levels of this pesticide also alter energy metabolism in flight muscles of adult worker bees, or indeed other pollinating insects? If so, how persistent are these effects? We hope to provide answers to these questions by conducting further experiments.