I think Arianta arbustorum is a very beautiful snail:
I found where they live when I was up on the north coast of Scotland last Easter and had decided to collect as many as I could find (250 snails in 2 hours!) with the specific purpose to discover whether theses snails could be killed by Phasmarhabditis hermaphrodita and if they would encapsulate and kill the nematode. It just so happens that P. hermaphrodita is unable to kill these snails and it fuses the worms to the inside of the shell – much like many other snail species. I published this in the Journal of Molluscan Studies recently. I had combined this experiment with the data I collected when visiting Liverpool museum conchology collections. I found that A. arbustorum shells that were collected over 50 years ago still have the nematodes fused to the inside, which you can see faintly in the picture below. What does this all mean? It shows that P. hermaphrodita is not very good at killing snails and that nematodes will remain in the shell of A. arbustorum for a long time which could allow for genetic investigation. Jolly good.
I know this blog is largely devoted to all things Phasmarhabditis but there are a few other species that I’ve been dabbling with recently notably the Entomopathogenic nematodes (EPNs). They are fascinating creatures that have evolved a symbiotic relationship with bacteria that they puke up when they infect an insect. This causes the bug to die in 24-48 hours as the bacteria are super toxic. You can buy these nematodes online to treat any insect pests you have in your garden. We were interested to see if EPNs could be used to kill aquatic insects such as Chironomid larvae. These can be quite pestiferous and the methods to control them currently are a bit flawed. Therefore, in a paper published recently we showed that nematodes can infect, kill and reproduce in these micro hosts and propose that they could be used in the field.
Off I went down to the Natural History museum in London fresh faced and buoyant from the recent publication of my shell paper keen to observe some more snail shells and expanding from the museums of Liverpool and London. I remember during my epic screening of as many snail shells as possible (probably about 5,000 over last spring/summer), that one of the most interesting groups was that of the genus Partula. They are very beautiful snails in with red, orange, yellow and white shells.
I remember that many of the shells I looked at in Liverpool museum had nematodes encased in them. These snails feed on fungi on the forest floor and used to be found on several islands in Polynesia. I say “used to” as many species have gone extinct due to human stupidity. Many moons ago the giant African snail was introduced to these islands and started munching all the crops, therefore some real bight sparks thought it would be a good idea to introduce the carnivorous snail (Euglandina rosea) to eat them all. This backfired spectacularly and they ended up eating all the indigenous Partula. So much so that many species are actually extinct. Great. Stuff. Guys. Nevertheless, eminent heavy weight evolutionary biologist Bryan Clarke started a captive breeding program to save the poor blighters. His work was inspired by that of Henry Crampton who patiently plodded around three island (Moorea, Mariana and Tahiti) collecting, analysing and measuring all the Partula he could find. His main aim was to understand whether or not the differences in shell colour were due to selection or were completely random. He came to the conclusion that they were random as although there were differences between different locations and ecological niches of the island he couldn’t fathom what the selection pressure could be. What about nematodes eh? I could be concentrating on keeping things a bit more domestic looking at why Cepaea nemoralis has different bands and colours but I thought I would expand to these wonderful tropical snails and have a look if there are any differences between the numbers of nematodes trapped in Partula shells from different ecological niches, islands and different species, as well as looking at differences over time. Hence, I’ve gone down to London to grab a few boxes of Bryan’s snails and I’m going to spend my last few days before teaching looking through them all for nematodes. It felt pretty good to go and have a look at these snails as they have been so well studied and a focus for evolutionary biologists for over 100 years. And that evening I sat down to screen through a couple of boxes from 1962. They are rather small and fiddly little blighters but yes there were nematodes in the shells that were over 50 years old….
In my spare time I like to get as inebriated as possible. It’s true. I’m from Scotland. Beer or wine, wine or beer or beer with wine, whatever there blooming well is in the house – it’s party time. But recently I was concerned about my drinking, not in anyway to do with the health aspects but I was wondering how long it could go on for. This Brexit thing was really getting me down. Universities were shedding staff, the economy was predicted to flat line and I was concerned about how I could afford great British booze in post apocalyptic Blighty where our great British pounds will be worth absolutely sod all. To remedy this I’ve recently got into brewing beer. I’m not too sure why I didn’t take up this hobby 20 years ago. What’s not to like about brewing 40 pints of delicious beer at one time? I mean 40 pints! Wow. Anyway, to banish the Brexit blues I immersed myself in all things brewing related for the afternoon and brewed myself a batch of beer (good alliteration). I had everything I need (yeast, grain and hops) even my brew dog, who looked as miserable as ever.
Three types of malted grain (Munich malt and 2 others I can’t remember) were boiled for half an hour. Then the wort was then boiled for a further hour with hops. Then mixed with yeast and left for 2 weeks as the yeast convert the sugars into God’s greatest creation, alcohol. Then it is bottled with a little sugar and left for a couple of weeks. This batch worked really well as I cultured loads of yeast for a few days before hand once I had added it to the sugary hoppy mixed the years were working within an hour.
I still had a month to wait before I could drink this batch but in the meantime I ended up cracking open a bottle of a batch I made several weeks ago. As I popped open the bottle and gulped down the heady brew I realised quickly how disgusting it was. Tinny, thin, with a trace amount of alcohol it was clear I had an incredible amount to learn about the art of brewing beer. I had had dreams that perhaps I could open a microbrewery instead of teaching biology and start a new life but it seems I’m better off just buying the stuff that or sticking with drinking the dreadful concoction. Bleurgh…
On the plus side I really need a helluva lot of chestnut slugs for experiments and I found that using the boiled grains as an attractant for slugs worked really well. I added a few spoonfuls to under a bit of matting and the next day hey presto there were a good few. Nice little tip for budding slug collectors and amateur brewers out there.
I was in Staithes. What a beautiful little place it is. A little picture postcard fishing town on the north east coast. I was plodding around the coast line staring at the calm sea and was being heated nicely by the warm summer sun, which was a welcome relief from the week long deluge of rain we had recently. I was plodding around with dog checking out the coastline and harbour, the beaches and bars. It was great. Captain cook worked here in a shop that has now fallen into the sea. I was walking in the footsteps of heroes.
I wasn’t really thinking about work and slugs and snails and nematodes such as beloved Phas when I stumbled upon the habitat that I had spent so long collecting snails such as Cepaea nemoralis, C. hortensis, Arianta arbustorum and Cornu aspersum. High up on the coastline peering down upon harbour and sea there were lots of C. aspersum just going about. Some had white shells due to the wind and salt, I presume. I would be taking a few of them back with me after the holidays.
I had recently started working with a couple of undergrads looking at the behaviour of Phas to slime of snails in particular different morphs of C. nemoralis and C. aspersum from different locations. I had collected C. aspersum from Liverpool, Formby and Thurso in the very north and Staithes on the north east coast would be an ideal location so I nabbed a few before I went back. Why bother? We had shown over 10 years ago that Phas was attracted to slug and snail slime and that they prefer certain species or rather are more attracted to certain species. I had shown this could be due to producing more offspring on them which would make some sort of sense but was only a weak relationship and warranted further examination. Also all this work with Phas had been done on the commercial strain and all this knowledge is based on this strain that has been grown under lab conditions for over 20 years. I suspect there may be some.lab evolution on the go and not necessarily in a good way. The way that nematodes are grown en masse is in large fermenters with 1 bacterium as food which was chosen as it produced the largest number of consistently virulent worms. If they are grown like this for decades without going through a natural host or even seeing the natural environment what effect would that have on them? Similarly, it would be predicted by geographic mosaic theory of co-evolution that Phas strains from specific locations will be in a constant battle with hosts such as snails that are present in the same locations – therefore Phas isolated from Liverpool Sefton park should be more adapted to snails from the same location. We sought to test this by looking to see if the commercial strain and several naturally isolated Phas strains would indeed be more attracted to hosts that live in close proximity to them. The snails of Staithes would provide a good location in the north west – let’s see how Phas responds to them…
Amazingly, I actually have a fully funded PhD specifically about Phas that is now available. So if you know anyone that is interested in this little worm then please forward on the advertisement which can be found here.
What’s it all about? The commercial strain of Phasmarhabditis hermaphrodita has been in culture for over 20 years. It’s about time that new strains were investigated to see if they are better at killing slugs and can be grown better. I’ve been collecting strains and species of Phas for a while now and they are sitting in an incubator waiting to be tested. Therefore, I need a postgraduate student to see if these strains are more pathogenic than the commercial strain. The PhD is fully funded which means that the successful student will get approx. 14 grand a year, tax free, as well as money for equipment, conferences and we will collaborate with BASF who make the commercial strain of Phas. There is plenty of room for learning lots of new skills e.g. molecular biology as well as publishing papers and travelling to conferences. Sounds good? I hope so – I’m excited about it.
I was still very happy that my shell paper was published in Scientific Reports. I wanted to publicise this has much as possible so I ended up writing an article in the Conversation which can be found here. But in the meantime it was getting written about elsewhere. Specifically, it was being blogged about here and it even made it to an online magazine called the wire and I got asked to answer a few questions about it, which I enjoyed very much, it can be found here. So all in all the coverage was very good indeed. On a completely different note I was waffling on about parasites that control the behaviour of hosts again, which can be found here. Or if you want to see the sort of cutting edge research I do have a look here.
I probably should have been trying to follow up this work by spending the summer working with the shells and trying to extract more nematode DNA or culturing the snail shell cells or something but I wasn’t I was busy in the lab with other projects. The next step for the snail shell stuff all depends on getting a nice lump sum of cash. I’d like to combine looking at the nematodes from conchology collections in museums with genome sequencing. I had found, for example, that Cornu aspersum were riddled with C. elegans, if this is a common association then it would be possible to look at the evolution of this species over time maybe hundreds or even thousands of years. That would be very cool as nematodes don’t fossilise well but they may do in snail shells. As the preserved nematodes will be cut off from water and high temperatures there is a distinct possibility that the nematode DNA would be suitable for analysis. This is something I really need to look at more.