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11th August

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Deciduous fringe of coniferous plantation.

I've had the idea for this page for some time, but had to wait for the proper time and specimen(s). I usually show pictures from a given location, but today all pictures are from a single specimen of Eared Willow - Salix aurita. The number of species make this little bush an eco-system in its own right.

Early sun, then dull.

Almost all Willows in this area are severely damaged by Plagiodera versicolora - the Willow Leaf Beetle. Adult (left) and larva (right).

    

The larvae eat the under surface of the leaf which then dies and turns brown in the affected area.

Notice that there is also some fungal rust on the leaves. I wondered how the association of the fungus and larvae might affect either of the organisms and found this:

1 Willows often need to cope with attack by both rust fungi and herbivores. We studied whether rust infection on willow affects the herbivore, and vice versa, whether herbivore feeding affects the fungal infection. The system investigated by laboratory bioassays and greenhouse experiments consisted of the willow hybrid Salix cuspidata, the rust Melampsora allii-fragilis and the willow leaf beetle Plagiodera versicolora. Effects were studied both on a local scale (rust infection and feeding on the same leaf) and systemically (rust infection and feeding on different, but adjacent leaves).

2 Rust infection was not affected by herbivore feeding on a local scale. Systemically, however, the willow's susceptibility towards rust infection was increased by herbivore feeding, as indicated by a higher number of rust sori on leaves adjacent to feeding-damaged leaves. The herbivore's performance was detrimentally affected by rust infection: increase of mortality (systemically), decrease of larval weight (locally and systemically) and prolonging of developmental time (locally and systemically).

3 Previous rust infection enhanced systemically the willow's susceptibility towards subsequent fungal infection. Previous herbivore feeding on the willow had no effects on the herbivore's developmental time and mortality. However, feeding upon previously feeding-damaged willow leaves significantly reduced larval weight.

Abstract of:

Herbivores and pathogens on willow: do they affect each other?

Authors: Simon M.; Hilker M.

Source: Agricultural and Forest Entomology, Volume 5, Number 4, November 2003, pp. 275-284(10)

Here's a close-up of the (presumably) Melampsoria rust.

Willow Tar-spot - Rhytissma salicinum - is also quite common. This tiny (4mm) yellow fly was moving from tar spot to tar spot and feeding. Was it eating spores?

     

This leaf (and many others) had shelters spun by moth larvae. The leaf immediately below the shelter shows evidence that the (now departed) inhabitant had been there for some time.

 

This Sawfly larva was responsible for large gaps in the leaves. These larvae usually feed in large groups, but this one was on its own. About 4 mm long.

This little spider was also hanging around. Notice the damage to all the leaves in the background.

And finally, a definite victim of the Entomophthora muscae fungus. The Dung-fly has been killed and the fungus can be plainly seen on the wings and thorax.

After I had left, I realised that I could have got Lecanora spp. lichens around the trunk at ground level.

Still, not a bad list of species:-

Rust

Leaf Beetle

Yellow Fly

Tar Spot

Spider

Sawfly larva

Moth larva

Dung-fly

Entomophthora

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