UK fights bark beetle invasion with sniffer dogs and drones

Across Europe, bark beetles have left a trail of destruction; they attack and compromise spruce trees, which they have killed by the million. Now, these tiny creatures are increasingly invading the UK, arriving - it turns out - across the channel by air under their own steam. But scientists are racing to stop them. And armed with drones, traps, and now even sniffer dogs, they’re taking the fight directly to the beetles. Here’s Max Blake, head of tree health at Forest Research…

Max - Spruce really underpins our forest industry. Conifers, and spruce in particular, grow far better in our conditions to produce more valuable wood than any other tree. They are largely free from significant pests and diseases. But the risk that we're looking at here, Ipstibagraphus, is the most significant pest in Eurasia of spruce species. So it feeds on a few different species like Siberian spruce, a bunch of different species in Japan and China.

Chris - And when you say it feeds on them?

Max - So a male will begin to bore into the bark and it'll make a little nuptial chamber, attract a female, the female will come in and then begin to make what we call a maternal gallery, which will go vertically up the tree. And then usually if the male's lucky, he'll attract a second female and she'll go down the tree. And what you end up with is two very straight tunnels going up the tree. And the female will lay eggs on either side of this tunnel. And that's where the larvae come from. And the larvae will begin to eat, radiating out from that. So you get this remarkable pattern coming out from these galleries. And what they're feeding on is tissues in the tree which transport nutrients up and down from the roots to the leaves and vice versa.

Chris - Do they compromise the tree then? So once they start doing this, does this kill the tree, just stunt the tree? What's the impact?

Max - They will eventually kill the tree. So when there's enough of these galleries produced by enough beetles, they'll girdle all of these tissues. And it's kind of like having all of your blood vessels suddenly blocked up. Now, typically it doesn't really do that. So what it normally does is it feeds on storm damaged trees, trees that have been particularly drought stressed, things like that. So trees that can't really defend themselves. Normally that phloem network is very well defended because of course it has to be. This is the main thing that's keeping that tree alive. So they're able to flush those galleries with resins which kill the beetles if they're healthy.

But if they are weakened, then that's sort of when it can come in. So it was unprecedented for us when we found Ipstipographa satchiphae breeding here in the UK back at the end of 2018. We didn't know why it was there. We eventually realised, and this was one of those realisations where your gut almost gets ahead of the direct evidence, and we were certain that they were able to fly over the channel from outbreak populations in Belgium, France, and probably northern Germany.

Chris - Does this mean all your fears are being realised? And what can we do? Now you've identified that these guys can come by air. What will you be doing about it?

Max - The fact that they can go on these air channels and fly far further than we ever thought possible looks on the one hand to be very scary. We also know that we need to jump in and catch populations when they're very small to have a better chance of eradicating them.

Chris - But that's difficult, isn't it? Because if they're small, they're hard to spot. So how can you find them? How do you know where to centre your attention?

Max - They are remarkably hard to find. So the exit holes and the entrance holes that they produce on the trees are about three millimetres wide. We've managed to find just single galleries by eye in entire woodlands just made up of pure spruce, which might be 10 or 20 hectares. It takes an awful lot of very painstaking work on the ground to go and find these. But the fact of the matter is that as our surveillance has increased, we're also looking at trying to be as efficient and as quick as possible. And that's where adopting some new techniques takes place.

Chris - So what do they look like, these new approaches?

Max - So we've been looking at the use of drones, that's quite obvious. So we use a lot of satellite data and a lot of helicopter photography. So we can go around quickly, photograph an area of spruce from the air, and we'll keep an eye on that over the years to see if there's storm damage or if there's any decline. But what helicopters struggle to do, obviously, because you don't particularly want to be flying a helicopter too close to any trees, is give us really high resolution data, and in particular, look beyond that to the ground floor. And that's where drones come in. So we're able to use drones to more quickly survey some of these areas. The other area that's got significant potential is using sniffer dogs. Sniffer dogs are fantastic at trying to detect ips in timber stacks. So if you've ever been to a forest, someone's fell parts of the forest or thin it, you can have these huge timber stacks, which are themselves very dangerous. Of course, each log will weigh a couple of hundred kilos. You don't want people clambering over that to try and find small galleries. And also a lot of it is inaccessible, but it's not inaccessible to a dog's nose.

Chris - So are dogs and drones going to cut it then? Do you think, are you confident with what you can do with these tools now? Do you think you can hold this in check? Or should we be looking for an alternative source for our telegraph poles?

Max - Yeah. So both dogs and drones have got a part to play in this. The programme of work is vastly larger than it was when we started this back in 2018. So we're in this very strange scenario where things are much worse than they seem. In other words, more beetles are coming over more regularly than we ever thought possible. But also things are much better because they do seem to struggle to actually persist here in some sites. So that is a really active area of research at the moment. We're trying to understand why they seem to be able to persist on some sites and don't on others. And then we can begin to look at long-term adaptation, especially thinking about that next outbreak instead of 20 or 30 years time.