The impact of pesticides on pollinators is highly contentious, but it’s just one of several factors affecting their health, according to a bee expert.
“There are several stresses that are stressing the immune system of the bee,” said Ramesh Sagili, an Oregon State University bee researcher.
Sagili was recently elected to chair a task force on pollinator health created by Oregon lawmakers earlier this year.
There’s insufficient evidence that pesticides are causing the decline of bee colonies, but studies certainly indicate some chemicals must be used with caution, Sagili said during the task force’s first meeting on June 30 in Salem, Ore.
Part of the problem is it’s difficult to realistically gauge how much contact pollinators are having with toxic pesticides, he said.
For example, it’s unclear how many times a bee may return to the same plant, increasing its exposure to the chemicals, Sagili said.
“The science is all over the place,” he said.
Nonetheless, it’s likely that a class of relatively new pesticides known as neonicotinoids have “sublethal” effects on bees, compromising their foraging behavior, homing ability and memory, he said.
These aren’t the only chemicals that may affect bees, though.
Residue surveys have found 121 different pesticides in bee hives across the U.S., some of which may have a “synergistic” effect when combined, Sagili said.
“There can be interactions,” he said. “They can get into the wax comb and stay there for a while.”
Pesticides serve a useful role for beekeepers, on the other hand, in controlling pathogenic mites, said Sagili.
Mites are one of the main threats that have impaired bee survival in recent decades, he said. “It’s not only sucking the blood of the bee but it’s transmitting viruses, which can deal a fatal blow.”
Bees that don’t pollinate a variety of different plants may suffer from malnutrition, Sagili said.
In North America, honeybees may also be less resilient than those in Europe, where the species originated, he said.
European honeybees were brought here in 1622 and don’t have as much genetic variation, Sagili said. “Our genetic diversity is low as well.”
While pesticides aren’t the only consideration in pollinator health, they were the prime motivation for the task force.
House Bill 4139 would have originally restricted the use of neonicotinoid pesticides but was eventually amended to create the task force, which may recommend future legislation.
Rep. Jeff Reardon, D-Happy Valley, said he wants task force members to identify ways that lawmakers could act quickly to improve pollinator health.
The task force may want to focus on better informing pesticide users about using the chemicals responsibly and develop a funding mechanism for such outreach, he said.
Education alone may not be enough to prevent misuse among “backyard” pesticide users, said Aimee Code, pesticide program coordinator for the Xerces Society non-profit group.
The task force expects to meet several more times over the summer before issuing a report to the Oregon legislature by Oct. 1.