Researchers develop new indicator of honeybee toxicity
Widespread declines in pollinator populations and other beneficial insects threaten production of pollinator-dependent food crops, wild plants and natural ecosystems. The use of insecticides in agriculture and other settings is believed to play a part in this decline. A project conducted by the Pennsylvania Agricultural Experiment Station aimed to better understand and mitigate the role of insecticides in the widespread decline of pollinators and other nontarget insects in recent years.
A team led by Penn State researchers Integrated federal data on insecticide use, toxicity and crop acreage to generate county-level annual estimates of honeybee “toxic load” from 1997 to 2012. The team defined toxic load as the number of lethal doses to bees from all insecticides applied to cropland in each county. The researchers generated separate estimates for contact-based toxic loads, such as when a bee is sprayed directly, and oral-based toxic loads, such as when a bee ingests the pollen or nectar of a plant that has recently been treated.
The data show that the total toxic load of insecticides applied to U.S. agricultural landscapes has become significantly more toxic — over 120-fold in some Midwestern states — to honeybees when ingested. The northern Great Plains had the second highest increase at 53-fold. These increases largely are due to the rising use of neonicotinoid seed treatments in corn and soybean. This study is the first to identify geographic patterns of insecticide toxicity to bees and reveal specific areas of the country where mitigation and conservation efforts could be focused. This new indicator can serve as an alternative to the commonly used measure of “pounds of insecticide applied” in cases where impacts to bees and other nontarget insects are a concern.
Link to full statement on website: http://landgrantimpacts.tamu.edu/impacts/show/6159