Popular insecticide used in Costa Rica damaging wild bee populations, study says

April 23^rd, 2015 (InsideCostaRica.com) A popular, but controversial type of insecticide used in Costa Rica and widely around the world is damaging wild bee populations, which are necessary to pollinate crops and sustain ecosystems, according to a new study.

Honeybee hives, on the other hand, were not affected by the chemical, from a class known as neonicotinoids.

Neonicotinoids are a class of nuero-active insecticides chemically similar to nicotine, originally developed by the Shell Oil Company and Bayer.

Neonicotinoids have been registered in more than 120 countries. With a global turnover of more than $2 billion in 2008, they represented 24% of the global market for insecticides.

Environmentalists have blamed neonicotinoids for the decline of both wild bees and honeybees in the United States and Europe. The European Union imposed a two-year ban on the chemicals in December 2013.

Neonicotinoids are used widely around the world to control crop pests. Seeds treated with them grow into plants that carry a small dose in their tissues. Insect pests that eat the plants die, but other insects are unaffected.

But the chemicals also get into the plants’ pollen and nectar, where bees are exposed to them.

Wild bee decline

In the latest publication, in the journal Nature, Maj Rundlof of Lund University and colleagues in Sweden studied bees foraging in fields of canola, also known as oilseed rape.

Half of the fields were grown from seeds treated with neonicotinoids and half were untreated.

“The most dramatic result we found was that bumblebee colonies almost did not grow at all.” in the treated fields compared to untreated sites, said Rundlof.

Overall, there were roughly half as many bees per square meter in treated fields as in untreated ones.

The contribution of neonicotinoids to the global decline of wild bees “may have been underestimated,” the authors conclude.

Honeybees unaffected?

Even the one piece of relatively good news from the study, that neonicotinoids did not seem to affect honeybee hives, presents a problem because regulators study honeybees when deciding whether to approve a new insecticide.

“It’s not very good if the model organism isn’t very predictive of what we want to protect,” Rundlof said.

The results are “pretty dramatic,” said entomologist Dennis vanEngelsdorp at the University of Maryland, who was not involved with the research.

But while it is becoming clearer that neonicotinoids can harm wild bees, vanEngelsdorp said simply banning the chemicals may not be the answer.

“In many cases, [neonicotinoids] are actually the safest alternative,” he said. If they are banned, “what you’re doing is forcing farmers to use products that may either be just as bad or worse.”

Treated seeds are practically ubiquitous, vanEngelsdorp said, and it may be time to rethink that approach. “We have to use pesticides wisely,” he added. “There is no free lunch with applying it ‘just in case,’ because we are damaging the ecosystem doing it that way.”

And, despite this most recent study, other research has indicated that the chemicals may in fact be related to colony collapse in honeybees.

Possible risks to humans

The European Union warned in late 2013 that two neonicotinoid insecticides, acetamiprid and imidacloprid “may affect the developing human nervous system.”  Both of the insecticides are also used in Costa Rica.

Research conducted by the European Food Safety Authority suggested the two insecticides “may adversely affect the development of neurons and brain structures associated with functions such as learning and memory.”

This story was based on an original report by VOA’s Steve Baragona.

RELATED: Two insecticides used in Costa Rica a risk for human nervous system: EU