The following is adapted from an article previously published by Bayer.
For more than 20 years, pesticide safety testing has included a battery of tests on the honey bee (Apis mellifera L.). The choice of the honey bee for testing makes sense; our relationship to honey bees dates back thousands of years. Yet, growers increasingly rely on other managed bee species to pollinate their crops, and unmanaged wild bees also provide pollination services, playing a significant role in certain landscapes.
Recognizing this diversity, regulatory authorities are calling for expanded safety testing that encompasses a broader range of bee pollinators. In response, scientists around the world are evaluating to what extent results from honey bee testing are applicable to protect other pollinators. They are also working on developing standardized testing systems to assess risks posed by pesticides to bees other than honey bees, or non-Apis bees.
The task has not been simple. Even with just a fraction of the over 20,000 species of bees buzzing worldwide, ensuring that the use of crop protection products is safe for bees requires knowledge and experience still being gathered. The development of a standardized test takes time.
In the case of non-Apis bees, the development process can either build on experience with other species or take even longer because experts must discover relevant details step by step. The less that is known about the bees subjected to testing, the longer the process to develop appropriate tests takes.
Even simple protocols can be thwarted by bees’ idiosyncrasies. To see whether and how much of a certain compound has an impact when consumed by honey bees, 10 individual insects are placed in a chamber attached to a syringe filled with a test compound and sugar water. The bees lap the mixture from the syringe; the tester knows exactly how much was consumed by the group because honey bees share food, going as far as feeding each other.
Since bumble bees are social, it seemed straightforward to use a similar test for that species. “Not so,” said Dr. Nina Exeler, who leads the Experimental Unit Bees at the Ecotoxicology Department of Bayer Crop Science in Monheim, Germany. “Bumble bees don’t share food. So, to determine consumption of one individual, we had to put single bees into chambers with a feeding syringe. As it turns out, however, bumble bees won’t eat if they feel, well, alone.” As such, additional adjustments were made.
This highlights the most pressing issue in non-Apis bee testing: the impracticality of testing all non-Apis bee species. It will be necessary to leverage knowledge gained from species that can be tested to make inferences about others and devise protection strategies that secure their health while keeping overall testing requirements manageable and meaningful.
“It boils down to one essential question: Is our current honey bee risk assessment protective of other species?” said Dr. Daniel Schmehl, of Bayer’s Pollinator Safety Group in the U.S.
Many authorities and researchers believe comprehensive protection will require additional species testing, as understanding how to confidently ensure pollinator health beyond the honey bee will require more information. At this point, data suggest that honey bees are the most sensitive of the species tested to date. Bumble bees appear to be the hardiest. In other words, testing honey bees may prove to be a good way of protecting other species.
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