[Pollinator] Details of Virginia Linden Tree Bee Kill and insights on Bee Sampling

[Steve Ellis]

Aimee,

Thanks so much for this detailed incident account.  Field incidents are FAR
TOO RARE, yet essential if we are to have an informed discussion.

One detail question: with apis mellifera, you indicated "6 dead workers,
one female".  With apis mellifera, (honey bees), my understanding is that
all workers are infertile females.  Am I misreading your entry?

Again this kind of hard data related to neonicotinoid poisoning is hugely
helpful.

Thanks for the work and sharing it with the group.

As my bees are starting to work the blooming basswoods in Minnesota today
(linden) I continue to wonder of the effects of low level neonicotinoid
exposure----

Vera K. and I tried to quantify the exposure, in my bee territory,
unsuccessfully.🤔

Steve Ellis

On Wed, Jun 27, 2018 at 12:10 PM, Droege, Sam <sdroege at usgs.gov> wrote:

> All:
> As Aimee code from Xerces mentioned previously there was a Linden tree
> associated  kill event in Reston, VA
>
> Table below documents the species involved (I did all the identifications)
>
>
>
>
> Queen Worker Male Female Unknown  Total
> Bombus bimaculatus 21 160 100 281
> Bombus impatiens 26 134 160
> Bombus griseocolis 5 62 47 114
> Bombus perplexus 28 521 40 589
> Bombus unkown  25 25
> Xylocopa virginica  23 42 23
> Apis mellifera 6 1 7
> Megachile mendica 10 10
> Megachile gemula 1 1
>
> Andrena vicina
> 11 11
> Andrena pruni 1 1
> Andrena perplexa 5 5
> Andrena barbara 6 6
> Andrena species  2 2
> Eucera rosae  1 1
> Total  80 883 210 38 25 1278
>
> Here is what we know:
>
>    - 3 trees involved
>    - *Tilia cordata *(note:  this species is not associated with Linden
>    poisonings in Europe)
>    - Trees were in parking area of a residential area of Reston, Virginia
>    - At least 2 trees with noticeable soil injection points
>    - Management company said they were treated in March and had been
>    treated every year for about 6 years
>    - Unclear what chemicals were involved or whether treatments changed
>    or whether more trees were treated elsewhere
>    - Company was advised by their lawyers to no longer speak to anyone
>    - 3 people reported the kill but no kill was reported in previous years
>    - Most of these bees were picked up on one day
>    - 500 or so were picked up by State of Virginia for analysis and not
>    available for species determination
>    - Management company would not allow additional collections
>    - Trees were not netted after kills were known
>    - Note that only 6 *Apis *were found...despite much greater activity
>    ...likely they took nectar back to hives, not clear if there was honey bee
>    mortality at the hives
>    - A chemical assay of bees and flowers will be made by the state
>    - Pattern is very similar to those of Oregon Linden mortality
>    events...and seems likely to involve neonic treatment
>
> We are looking at followup studies to see if mortality continues in
> subsequent years pending permissions
>
> Note that the kill documented here is only part of the total kill
>
>    - Birds were actively eating the dead and dying bees
>    - Bees could have flown off and died
>    - Small bees were not found...but were likely present
>    - Mostly bees were collected from only 1 day, the tree would have been
>    blooming several additional days
>
> Who knew...
>
> There were so many bumble bees in the area....this is good news from bad.
> I think we often in our minds underestimate the true number of bees in an
> area.  Here we are in average suburbia with lots of development and have
> this many bumble bees at one place.  When sampling bees we never reach
> anywhere this number under any circumstance I have seen.  Thus we have to
> wonder how representative some of our low number samples might be, with the
> notion that we need to probably err on higher capture rates in our studies
> rather than lower.
>
> sam
>
> The earth has many keys,
> Where melody is not
> Is the unknown peninsula.
> Beauty is nature's fact.
>
> But witness for her land,
> And witness for her sea,
> The cricket is her utmost
> Of elegy to me.
>
>    - Emily Dickinson
>
>
>
>
>
>
> --
> *Why Did you Mow My Flowers? *
> *- Bee*
>
>
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