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Neonicotinoid pesticides can reduce honeybee colony genetic diversity

Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness). As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0186109
 

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Certainly an interesting study. I think that if there is a causal link between neonicotinoid use and honey bee colony demise, it will be shown to be a sublethal sort such as orientation or breeding issues.

However, I do want to point out that this study was of 24 queens -- 12 control and 12 treated. Before I think any real takeaways can be had from it, I would like to see the results repeated on a much larger scale.
 

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What all the studies leave out is the primary stressors of bees currently -- poor nutrition, Nosema, Varroa, viruses, adjuvants in the tank mix. That is not even possible to account for with less than a hundred sample size. If the bees have any or probably several stressors, it is not solely what they were testing for, but in combination with what the bees already have.
 

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True enough. Drones that survive being raised with a varroa mite family in their brood cell have sperm count reduced by as much as 50% or sometimes more.
 

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Oh that's interesting I didn't see it.

I presume that's because they are less subject to varroa?
 

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It is the bee diseases carry by the varroa. A less healthy or sick bee will
have less motivation to do anything. It is almost like a helpless person when he/she
is sick. A healthy bee is all motivated to keep the hive strong and pass its genetics to
the next generation.
 

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Drones from treated hives outperform untreated hive drones also. I published that one about two yeas ago.
In my eyes this is the dominant problem here with mating our tf queens.
Drones from treated hives are much more healthy to mate with queens because they are raised in hives without much disease after winter treatments.
But this hives are not selected so have no survivor genes.

As tf drones which are diseased will have no chance on matings. The more resistant drones from selected tf hives will have but mix with the genetically virus susceptible treated hives drones which appear healthy.
So tf beekeepers here try to mate the queens very early in year ( when the other beekeepers have culled the drones) or as stress breeding in autumn ( after drones are pushed out in the other hives).
But this means danger of having a queen which is not much prolific.
 
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