Sunday, 9 May 2010

A new mystery and an old one

The solitary bee Andrena cineraria is one of our more attractive bees. Solitary bees tend their own batch of eggs which are laid in tunnels in earth banks. These tunnels are often found close together in aggregations, but each female still tends her own eggs.

This specimen was quite dead, and I have no idea why.

A long-term mystery has been solved. I've seen this yellow rust on Bramble many times, but I never got round to a proper identification. It's Kuehneola uredinis, and is very common.


Gill said...

"This specimen was quite dead, and I have no idea why." Cold nights? Fungus? (Is it too early in hte year for the pink-fuzz fungus that kills flies?) least it makes the photography easier!

Stuart said...

Entomophthora muscae is the pink fungus that kills flies, and I've seen it at most times of the year. I know of fungi that kill spiders, moth larvae, ants, aphids and wasps, but I can't find references to fungi that kill solitary bees, although there is one that attacks honeybees.

Closer examination of some of my images reveals what looks to be damage to the right side of the 'face', so maybe it was hit by a vehicle and died after landing.

I also considered that it might be a redundant male, but I can only count 12 antennal segments, and that would make it female.

Gill said...

"but I can only count 12 antennal segments, and that would make it female." You mean males have a different number? Is that true of all insects or just bees? One learns something new every day!

Stuart said...

The antennae of male wasps and bees are longer than those of the female, and the extra segment can be useful if you know what to count (13 vs. 12 in the case of Andrenas). In many moths and beetles the male antennae are more developed - often feathered or branched at the tip. In flies (where antennae are usually small) it's the male eyes that are larger, although some male flies also have feathered antennae. It's all to do with finding a female.

In Ichneumonids, both sexes can have long antennae. In males it's for finding a female; in the female it's for finding the host.

Just to add further confusion, Ichneumonids don't always need males: the females can reproduce by parthenogenesis, which is similar to apomixis in flowers.

There are a great many complex processes going on out there. I recently found out that female solitary bees lay their male eggs nearer the entrance to the tunnel to ensure that they emerge first, presumably so that they can establish their territory before the females emerge.