Nomada Andrena interaction, and IDing from?

[Dillybythesea]

Photographing this Andrena male pouncing on a sunning Nomada bee, I wondered if the interaction between them means that, if I could definitely identify the mining bee, I could extrapolate from that the identity of the cleptoparasite? Eg I'm thinking if it's an Andrena flavipes male, would it be safe to say it's Nomada fucata, or do they interact with others?

Secondly, re the action, I assumed it was an attack, but a clever friend suggests it might be that the Nomada bee has picked up the scent of a female Andrena flavipes and as a result the Andrena male is trying to mate with it.

Could anyone clarify, please?


url=http://www.wildaboutbritain.co.uk/archive/showphoto.php?photo=156511][/url]

[Dillybythesea]

Picture doesn't seem to want to enlarge. Sorry, I'll try again...

[Jason Green]

Afternoon Rhona,

It doesn't look like an attempt at copulation to me. Rather, the Nomad has been caught trying to enter a nesting hole and is now being confronted by the Andrenid who looks to have the upper-hand.

A fascinating encounter.

Take care,

Jason

[Dillybythesea]

Evening Jason!

Yes, it doesn't look like courtship, does it!

But watching males the other day on the cliff face pouncing on females trying to take pollen back into their burrows, and often bowling them down the cliff in the process, my jury's out!

ATB, Rhona

[JRsbugs]

That's a fantastic capture!

By reading the Nature Conservation site it does suggest males will jump on anything trying to mate.

Heathland bees

I see a lot of male Andrena buzzing around a shrub and bumping anything off that happens to be sat on 'their' shrub. I've seen one even walk on top of a 7-spot Ladybird to make it move! Flies, bumblebees, they will bump anything off!

I saw a male Andrena nigroaenea I think go under a leaf near the ground today, there I found a new nest which it went down. Shortly after it came out again, I wondered if it had detected the scent of a Nomada as I think it's not normal for them to go down a nest. There's several nests appearing suddenly with males buzzing around a nearby shrub, I saw a Nomada flying nearby yesterday. It suggests to me the males are trying to protect the nests. I got a pic of a male pulling a female to the ground near a nest but she escaped, it would seem to me they know what they should be mating with. Or, was he trying to protect the nest? There's more than one female and several males so maybe she was not 'his' female. I've seen the same thing with Megachile willughbiella, with more than one male it seems the male will protect his area against other females too.

[Matt Smith]

Male bees do not protect nest sites. They use scent to detect the presence of females, so the male may have gone doen the hole to see if an unmated female was present. If so it may well lurk in the area. Some years ago I was rooting around on a soft rock cliff in Wales and opened up a nest cell of Anthophora plumipes, a fresh female fell out. She was fully ready to emerge and sat in the sunshine for 10 minutes having a bit of a wash and brush up while she warmed up. In those 10 minutes 3 patrolling males had detected her scent and all were hovering a few inches from where she was sat - when she took off all 3 zoomed after here.

Scent gets the males to the right spot, but visual clues are important too. Patrolling males of many bee species will pounce on anything of the right size and shape, just in case it is a female. Sometimes they make mistakes, either pouncing on other males or bees of a different species. I would be hesitant to draw any conclusions regarding Nomada / Andrena species interations or getting Id's from what pounced on what.

[JRsbugs]

Originally Posted by Matt Smith

Scent gets the males to the right spot, but visual clues are important too. Patrolling males of many bee species will pounce on anything of the right size and shape, just in case it is a female. Sometimes they make mistakes, either pouncing on other males or bees of a different species.

Not only have I seen a male walk over a 7-spot Ladybird to make it move, I have seen them pounce on them too! Bumblebees, ladybirds, and smaller flies don't fit the correct size nor shape and they pounce on them all if they are on 'their' shrub.

[Dillybythesea]

Well many thanks, as ever. It's obviously not possible to draw any conclusions then, but great entertainment!