Study: Sperm count reduced in honeybees exposed to neonicotinoids

Wednesday, August 03, 2016 by: Daniel Barker
Tags: honeybees, low sperm count, neonicotinoids

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(NaturalNews) New research has revealed that neonicotinoid pesticides reduce the sperm counts of male honeybee drones, a fact that may at least partly explain the rapid decline of bee populations over the last decade.

For several years now, experts have been aware of a link between the widespread use of neonicotinoids and declining bee populations, but a recently published study was the first to definitively prove that these insecticides negatively affect the reproductive capacity of male insects.

A group of researchers from the Institute of Bee Health at the University of Bern, Switzerland, conducted tests on male honeybee drones to measure the effects of two widely used neonicotinoid insecticides, thiamethoxam and clothianidin, on the sperm of male honeybee drones.

The team took semen samples from sexually mature male bees that had been exposed to neonicotinoids at levels comparable to those found in sprayed fields. Their results showed a 39 percent average decrease in living sperm in the exposed bees, compared to those in the control group.

Neonicotinoids linked not only to male bee infertility, but also higher mortality rates

In addition, the mortality rate among male bees exposed to neonicotinoids was found to be almost double that of bees not exposed to the pesticides.

Honeybee queens require quality sperm to perform their role in maintaining the survival of the hive.

From New Scientist:

"Honey bee queens make a single mating flight from the nest to collect sperm from as many as 20 different males, which they store within a dedicated organ over their entire lifespan.

"This is vital for the survival of the hive, as it equips the colony with the genetic diversity needed to resist disease, parasites and environmental challenges."

Lead researcher Lars Straub said that if a queen bee does not collect enough quality sperm on her once-in-a-lifetime mating flight, the worker bees in the hive will sense that the queen is "ineffective," and will kill her – a scenario Straub and his colleagues have dubbed "game of drones."

Having to replace the queen is generally bad news for bee colonies:

"Replacement of the queen is costly as it hinders the growth of the colony. And as replacing a queen can only occur at certain periods in the year, colonies can sometimes go for long periods without one, putting them in danger of collapse."

It is theorized that neonicotinoids may damage sperm DNA and affect sperm motility, but the exact mechanisms are not yet fully understood.

The researchers were not particularly surprised to find that neonicotinoids affect the reproductive capacity of invertebrates, since other studies have shown similar results in "non-target male vertebrates."

U.S. continues spraying neonicotinoids while the EU reviews recent ban

The use of neonicotinoids has become a controversial issue – the European Commission is currently reviewing a 2013 temporary ban on their use – but in the United States neonicotinoids are still widely used.

For example, neonicotinoids are sprayed on up to 94 percent of corn crops grown in the United States, while U.S. bee populations continue to drop at an alarming rate.

Over the past ten years, beekeepers have reported an average beehive loss of 30 percent or more, with some losses in excess of 50 percent.

But bees are not the only victims of negative health effects from exposure to neonicotinoid pesticides. These neurotoxins are also a threat to other animals, including everything from birds to humans.

Neonicotinoid pesticide exposure in humans has been linked to brain and nervous system damage. It turns out that what kills unwanted crop pests is harmful to humans, too – a not so surprising fact, considering that all animals, including humans, share many basic biological traits.

What is surprising, however, is that it took so long for mainstream science to confirm the obvious ...

Sources:

NewScientist.com

RSPB.RoyalSocietyPublishing.org

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NaturalNews.com