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Bumble die-off/lingering deaths. Advice welcome.

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Hi. Bumble novice in North Wales here. We have a bumble nest either in a cavity in a stonebuilt wall accessed behind a waste pipe or under the adjacent roof of what I believe to be Tree bumblebees Bombus hypnorum

My neighour and I have been delighted to see lively activity over recent weeks (May and June) but now since the beginning of July I am getting very concerned by the number of dead and dying bees in the narrow yard which leads directly to the wall/roof nest site. The toll is five dead and three living do date.

Of the two living bees yesterday, one was literally in the last throws. Looked for all the world like it had gone into spasms and although on its side, it was making involuntary movements which sent it round in approx. 3-4 cm Ø circles. The second LB2 (see attachment) looked livelier, so I tried reviving it with sugar water. It did seem to feed, but sadly it died this morning. That means it took over 14 hours to die. Surely that is not “natural”.

I made some fuzzy less than useful film and terrible photos, but I would be much obliged if someone could advise if there is anyone in North Wales who is monitoring and/or studying Bombus behaviour and die-off who could advise me? Or if anyone is interested in observing the behaviour of the dying bees. Is there anyone collecting data and material? I have all the bodies and noted location found.

The nest is still active with lively coming and going. The size of these dead bees is 9 mm upwards. The smallest possibly being the smallest bumble bee I have ever seen before. The bees I can see accessing the nest all seem to be larger, but as it is at first floor ceiling height in a Victorian house, I may simply not be seeing the small bees from below.

Thank you for all help and advice.

     

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Joined 2016-07-12

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Hallo tobee

Sorry, no real help!

I´m a newbee as can be also, but I read some about them and have questions.  It could be helpful to take a very close look at those dead bumblebees. If they are boys, then maybe their time has been over…. boys might have yellow(?) hair in the face.
Did they carry pollen? if so, they are girls.

Anyhow, this sounds not like a natural death.

Did you take a close look at the wings? If they look very worn, the bb was maybe no youngster.

Can you find out if someone in the vincinity has used insecticide?
Especially neonicotinoids seem to have desastruos effects like ruining orientation in the alive bbees and ruining the number of offspring, there will be next to none.

Has a parasite killed your bb? Did a new different animal resurrect after the bbhost died?

Concerning the small bb´s, I readthose 2 really superb books of Dave Goulson and in one of those he describes a couple bb nests with individuals in very different sizes. This seems to be quite normal, but the smaller the bb, the more likely it stays home for other work, he describes the smallest ones never even seem to leave home.

Keep looking out. If especially bigger bb are now to be seen, then it might be the next generation of new queens. Try to identify!
If you manage to see were the take refugee for winter it would be interesting. I read that sometimes they take their winterplace very close to the old nest and sometimes even a view queens huddle together.

I hope I have not wasted your time totally for nothing.
Best wishes Bine

     
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Thank you for your response, Bine. You have some interesting thoughts and suggestions. Tree bumbles are new to the UK, having only been observed this century, not before. The individuals observed to date (dead and dying) appear to be workers, drones and virgin queens, so this die-off is affecting the whole population. I presume there is no local commercial use of insecticides, but they are freely available to the public, which sadly include neonicides. These bees have to fly long distances to forage and it has been a cold, wet time of late, so this will also have an impact viability. Although they may suffer from mite infestation, I cannot see anything with the naked eye. Certainly not of this nature: http://1.bp.blogspot.com/-olaTVkQnI4E/VaaEeZqQTRI/AAAAAAAAifA/Qd1-26YXrHg/s1600/Bumblebee+with+mites+15072015+(1).JPG

I continue to monitor the site, although I have been away for a week. The temperatures are currently below normal and the stormy wet weather is another factor which must affect this bee folk. We are in a village right on the coast, so they immediately only have a half circle of land to forage, not 360° hence only “half-capacity”, which in turn is not highly productive from a bee’s point of view. No flowering crops of rape, tree fruit, etc. but a high percentage of exotic garden flowers. I have lavender and teasels to help provide a plant source, but I notice most local gardens are pretty bee unfriendly and local farmers seem to be waging war on gorse, which has traditionally been an important bee food locally.

It all comes back to the usual explanation of depleted food resources, loss of habitat, climate change and human invervention i.e. insecticides. A strong and healthy population can survive the predations of mites, etc. but not those in a weakend state, whatever the cause. Let’s hope we can all play a part in preventing further losses at all levels, starting in the field and our own back yards, but ending in the boardrooms and parliaments!

     
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Hallo tobee

Thanx for updating me on your treebumbles. It´s so sad to hear that the whole colony suffers from losses.

I keep thinking, that maybe a limetree could be the culprit. There are lime varieties that cause death to bb´s while beeing uncomplicated to most honeybees. This I found in the Journal of apiculture science :
http://www.jas.org.pl/Issue/29
There are two articles on it nr. 7 and 10.

If empty stomachs are the cause, you might try to offer a sugary solution in a legoblock or a foodstation like this: http://www.das-hummelhaus.de/produktuebersicht Futterstation
To raise the interest you might even reuse your dead bb´s and place a couple at the food station, because bumbles like to learn from other bb´s sitting at the food: this is food.

Best wishes Bine

     
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Joined 2016-07-04

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Hi Bine Guten Tag smile

Your lime tree hypothesis does not apply to this colony because there are no lime trees in the area. It is very acid soil, so lime would not thrive or even survive unless in pots, and that is not likely because it is a coastal area with high winds, so potted trees are not an option. I think we can exclude lime as a cause.

The virgin queen did appear to feed, but died anyway. Thank you for the link to Das Hummelhaus. Sehr interessant! I have found bumbles/Hummel do not really need showing or teaching how to feed on sugar water, so I am intrigued by the idea.

One huge problem has been the weather this year. It has already been classed a disastrous year for butterflies, so I am expecting the same for other insects, especially bees and wasps. These deaths could simply be “natural” but brought forward by the change in weather patterns much as described in this article: https://www.theguardian.com/environment/2016/jun/29/climate-change-is-disrupting-seasonal-behaviour-of-britains-wildlife

The woodworm in our house is certainly on the move in July, whereas it should not be active until September. Maybe the same with the bumble die-off? Without testing, we are unlikely to know if it is chemical contamination or not. We cannot guess and of course all the “tests” and “research” done into the pesticides is done by the producers or through “independent” research which they fund!! Even the EU is now accepting their research and assurances and not respecting the cautionary principles it is supposed to.

Thanks again for your input. It is valuable to share experiences.

Regards from North Wales—ToBeOrNotToBee smile

     
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Hi, ToBeOrNotToBee,

You have probably given up hoping to get further feedback about your Tree BB colony, but perhaps I might be able to add something to what has been said already - and perhaps you might spot this late reply !

But first let me explain .......
I’ve been trying to understand and study Tree BBs for some years now.
I have a long term honey bee-keeping background, but became fascinated by BBs before BBCT was formed.

Beekeepers Associations tend to get deluged by worried householders in late May / June because they suddenly spot much bee activity outside a nest they hadn’t realised was there before.  (It’s usually on the line of ‘Help, there’s a bee swarm in my bird box’ etc.)  So this results in TBB colonies which need sometimes to be re-located, and are consequently study and know-how learning material for people like me.

I’ve had several colonies which I’ve brought back to my garden from such circumstances: and many of them have been re-located to the back of my garage.  As a consequence you get to see some common ‘outside the colony’ events and variations on the usual theme.
I’ve also had a totally natural colony in a bird box in the same location.
And I’ve also had a few colonies which I’ve transferred to a ‘bumblebee box’ with an inner Perspex cover, so you can see what goes on inside the colony - and what goes on at their ‘flight-point’.

From my experience so acquired, in early July I would expect to find occasional dead or moribund bees beneath a colony - and perhaps a small number each day for a period. 
These probably result from at least two normal routes.  1.  Natural die off of individual bees in the colony, with the corpse being removed from within the colony and dropped a short distance away.  2.  Male bees lying beneath the colony, often with what look like partially dislocated wings.  I think these result from collisions between individual males in the ‘Nest Surveillance cloud’.  You can sometimes hear quite sharp ‘bangs’ when they bump into each other; and both bees then fall towards the ground - and one or both may then recover their flight control to immediately re-join the cloud.  Sometimes these bees recover after resting, but more often they die.

A third factor which may come into play around that time of year would be a fairly rapid die-off of colony activity caused by the natural quite short activity cycle of TBB colonies - which last for only about 100 - 130 days from founding in say late February or March.

So maybe what you have seen is just parts of a natural process, not the result of a poisoning incident.

I’d greatly welcome your reaction to my ideas above.
Could your facts fit with the trends I have observed ?

Best wishes - and ‘Bee Good’ !

Clive

     
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Hi Clive.

Many thanks for your reply. (I have just managed to unsubscribe myself from this conversation, so may no longer receive any future posts and updates… How silly!) Anyway, yes, I suppose the die-off could have been natural, but ALL activity ceased shortly after the die-off I originally posted about. I have not seen any more bodies or activity around the nest site. Neither my neighbour or I are able to date when the colony was founded. I only noticed activity from early June.

Some observations on events and your suggestions:

+ I did not observe dislocated wings, but some of the bodies had started to decompose, so cannot say whether they had or not.
+ the small/tiny workers (I never have noticed such tiny BBs) were in the majority, but male and virgin queen were also amongst the “victims”
+ their prolonged death “throws” is not what I’d expect (not that I have a clue, but the “natural” death of creatures having reached the end of their life-cycle is surely more a “slipping away” and not a sort of “writhing in agony” or going into spasms over several hours event?)
+ the ‘Nest Surveillance cloud’ was more a solitary sentinel in this colony! I have since read about TBB and can honestly say our nest appears to have been a-typical in that respect.

I am quite jealous of your observation set-up! I must be fascinating to have such close contact and be able to see what is happening. Our nest is way up on high and of course nobody could see into it, even if they climbed up to look. Our birdbox on the side of the house did not attract them, but it is quite exposed. It should really come down, because birds have never been attracted to it and now we have too many magpies around… A TBB nest would be lovely, but I think they have more sense given this exposed coastal location.

Thanks again for taking the time to answer me. It is much appreciated. We will never know what happened, but I do hope the nest was viable. I’ll look out for activity in and around the neighbourhood next year.

Kind regards

ToBeOrNotToBee

     
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Good pic by the way.

     
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Thank you, Simple Shell.