New Study Says Insecticides Deadlier Than Ever for Honey Bees

Insecticides, as we all know, are one of the main reasons honey bees continue to struggle. While everyone knew how serious this problem was and remains to be, a new study coming out of Penn State University makes the situation direr than even we had believed. If the study is accurate, the toxicity of pesticides has become far more dangerous to honey bees than ever before.

Christina Grozinger, Distinguished Professor of Entomology at Penn State University, stated, “Insecticides are important for managing insects that damage crops, but they can also affect other insect species, such as bees and other pollinators, in the surrounding landscape. It is problematic that there is such a dramatic increase in the total insecticide toxicity at a time when there is also so much concern about declines in populations of pollinating insects, which also play a very critical role in agricultural production.”

The researchers concentrated on different contact-based toxic loads. Examples would be when a honey bee came in direct contact with a spray versus crops that had been sprayed versus seeds that were treated. What they found was that while the amount of insecticide sprayed had steadily declined, the toxic-load stayed relatively consistent, meaning the insecticides were increasing in strength.

Lead researcher Maggie Douglas stated, “This dramatic increase in oral-based toxic load is connected to a shift toward widespread use of neonicotinoid insecticides, which are unusually toxic to bees when they are ingested.” Grozinger added, “Several studies have shown that these seed treatments have negligible benefits for most crops in most regions. Unfortunately, growers often don’t have the option to purchase seeds without these treatments; they don’t have choices in how to manage their crops.”

Douglas would go on to add, “The indicator we use — bee toxic load — can be considered as an alternative indicator in cases where impacts to bees and other non-target insects is a concern. This is particularly relevant given that many states have recently developed ‘Pollinator Protection Plans’ to monitor and address pollinator declines. Ultimately, our work helps to identify geographic areas where in-depth risk assessment and insecticide mitigation and conservation efforts could be focused.” Grozinger further stated, “It is important to note that the calculation of bee toxic load provides information about the total toxicity of insecticides applied to a landscape. It does not calculate how much of that insecticide actually comes in contact with bees, or how long the insecticide lasts before it is broken down. Future studies are needed to determine how toxic load associates with changes in populations of bees and other insects.”

To see the full report, visit News.PSU.EDU