SoylentNews

Common Pesticide Appears to Reduce Live Bee Sperm

posted by n1 on Friday July 29 2016, @02:55AM   
from the none-of-your-beeswax dept.

Arthur T Knackerbracket has found the following story:

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.

---

Original Submission

• Some issues (Score: 1, Insightful) by Anonymous Coward on Friday July 29 2016, @08:59AM

  by Anonymous Coward on Friday July 29 2016, @08:59AM (#381456)

  Three cages per colony were randomly selected to assess drone sperm quantity and viability at 14 days post-cage assay initiation, the typical age drones reach sexual maturity [60,61]. Drones in these cages were carefully removed using a forceps; to prevent sperm from migrating into the penis bulb, the drones were dissected alive by pinning them onto a wax plate [62]. Following Carreck et al. [63] the testes, mucus glands, and seminal vesicles were removed from each drone, placed in a 1.5 ml Eppendorf® tube containing 500 µl Kiev+ buffer, and crushed to form a diluted stock sperm solution.
  [...]
  Samples were then incubated for approximately 20 min in complete darkness and then gently vortexed. Ten microlitres were viewed at 400× magnification using a fluorescent microscope (Olympus BX41, Switzerland) equipped with filter cubes for UV excitation [67]. Ten visual fields were selected for each sample so that the quantity of living and dead sperm could be counted; an average value was then calculated from these fields [67].
  [...]
  we hereby provide the first evidence that field-relevant concentrations of these chemicals can elicit effects on male insect reproductive capacity.

  http://rspb.royalsocietypublishing.org/content/283/1835/20160506 [royalsocietypublishing.org]

  What does the timecourse of sperm viability look like with age? Seems like an alternative explanation is that the insecticide made the bees mature a bit slower/faster. These sperm counts may not be a good proxy for reproductive capacity at all.

  Besides the usual pseudoscience of seeing a significant difference and leaping to some wild conclusion, there are other issues. For example, the paper contains no mention of blinding. It also contains basic statistical errors like "failure to reject the null hypotheisis means it is true".

  Another thing is that the sperm in the image provided by the phys.org article look like they may clump together and I notice they do not say the visual fields were selected randomly. So I have my doubts the sampling scheme is compatible with their chosen null hypothesis. Basically the experiment may have been designed to reject the null hypothesis no matter what since it assumes randomly selected visual fields and they didn't do that.

  Starting Score:	0		points
  Moderation		+1
  Insightful=1, Total=1
  Extra 'Insightful' Modifier		0
  Total Score:		1