A new study finds that a commonly used insecticide kills much of the sperm created by male drone honey bees, one reason why the bees are dwindling.
The class of insecticide called neonicotinoids didn't kill the drones. But bees that ate treated pollen produced 39 percent less live sperm than those that didn't, according to a controlled experiment by Swiss researchers published Wednesday in the journal Proceedings of the Royal Society B.
It essentially acted as an accidental contraceptive on the drones, whose main job is to mate with the queen—but not one that prevented complete reproduction, just making it tougher, said Lars Straub, lead author of the study and a doctoral student and researcher at the University of Bern. Drones, which are the product of unfertilized eggs, don't gather nectar or pollen and don't sting; they die after mating.
Both the drones that ate insecticide-treated pollen and those not exposed to the chemicals produced about the same amount of sperm. The difference was clear when the researchers put the sperm under the microscope: The bee that didn't have pesticide in its pollen produced on average 1.98 million living sperm, the one with neonicotinoids in its food about 1.2 million.
(Score: 1, Insightful) by Anonymous Coward on Friday July 29 2016, @04:14AM
We spray insecticide everywhere and then we wonder why insects keep dying and going extinct all around us. The answer is right there in the name, insecticide. The stuff works just as advertised.
(Score: 2) by butthurt on Friday July 29 2016, @04:25AM
It's surprising because this type of insecticide is thought to kill by affecting the nervous systems of insects. It's as though non-fatal amounts of nerve gas were found to act as a spermicide.
https://en.wikipedia.org/wiki/Neonicotinoids#Mode_of_action [wikipedia.org]
(Score: 0) by Anonymous Coward on Saturday July 30 2016, @02:48AM
The nervous system doesn't operate in a vacuum.
Two possible contributing factors include
"during periods of increased activity bees pump their abdomens to increase gas exchange, using expanded sacs of the trachea as bellows"
http://osu.libanswers.com/agnic_bees/faq/18733 [libanswers.com]
So the nervous may contribute to their breathing. Non-fatal amounts of insecticide may not be enough to kill the bee directly but it may be enough to hinder its breathing enough to reduce oxygenation which may impact their sperm.
Also the harm on their nervous system and on their breathing may make it more difficult for them to acquire as much food and care for themselves. This, again, may not be fatal to them directly but could be enough to contribute to their infertility.
I'm sure there are many other contributing possibilities but the point is that anything that harms them a little may not harm them enough to kill them directly but may still harm them enough to impact their ability to have functional offspring. Offspring requires investment and anything that makes it harder for them to make that investment will hinder it, possibly before it kills them directly.