The Asian Longhorned Beetle
Music Meet the Asian Longhorned beetle, a veracious feeder. It chews its way into trees and chews its way back out again. The telltale signs of ALB infestations are the beetles themselves and the large exit holes they leave in trees. What people don’t usually see are the huge channels called galleries the insects carve inside the tree. These tunnels weaken and eventually kill the tree. The adult Asian Longhorned Beetle lays eggs in the bark of the trees. The female will chew out a small circular area, about an inch long, chew that out of the bark and cut a little slit in the middle of it and she sticks her egg inside that slit. When the egg hatches, the little grub that comes out of it burrows straight down into the wood and it continues to feed there for the best part of a year getting larger and larger and tunneling all different directions until it’s cutting holes that are about a half of an inch in diameter. At this point the larvae forms a cocoon inside the tree and in a short time the adult will emerge and usually the adults will emerge in about a year after the egg was laid. Once the adult emerges, the cycle starts all over again.
The Asian Longhorned Beetle is native to China. It was first discovered in NYC in 1996. It was found in Chicago in 1998. Scientists believe this pest came to the United States from Asian ships. The vectors for this spread were wooden shipping crates made from trees that already contained Asian Longhorned Beetle larvae. This is a piece of lumber from a crate of some goods that were imported from china and you can see that this was cut from a tree that had been infested by the ALB and it has huge galleries in it. This is just a cross section, but you can imagine these galleries going in every direction on the tree. With this much damage to the tree, it’s easy to see how the tree would be injured or even killed. When these shipping crates got to this country, the insects left the dead scrap lumber and went looking for live trees to feed on. They found out they really liked maple trees. YUMMY!!!
They like to feed on maples, poplars and many of our softer hardwood trees, but they view maples about the way human beings would view Hershey bars. They just love to eat maple trees. “Music “ And that’s bad? Really bad because it bores large holes, large tunnels into trees and weaken trunks and it will weaken limbs and branches, essentially it will kill an entire large tree. ALB if it ever gets loose in PA. would be probably one of our major hardwood pests. I would imagine it would be more devastating than even the gypsy moth, because once the tree is infested there is no recovery. Youch!!! So this little insect can cause some big problems. The arrival of the ALB has resulted in the loss of trees and the wild life that use those trees for habitat. The loss of trees also means loss of shade and potentially higher city temperatures. Limbs or entire trees weakened by the beetle are dangerous and can fall on people. Since ALB prefer maple trees, this means a loss of maple syrup products and furniture wood. It can even be a threat to tourism if the beautiful fall leaf colors are reduced. The presence of invasive species means that the natural system is out of balance. So how do we correct it, or at least manage it? Just spraying poisons won’t necessarily restore the balance and it could cause even greater problems. That’s where I come in to explain that problems this complex require a more sophisticated approach, one we call “Integrated Pest Management” or IPM. Instead of a one shot approach, with Integrated Pest Management, scientists and public workers employ a pyramid of IPM tactics, starting with the simplest prevention techniques and moving up the scale to more complicated intervention. At the bottom of the pyramid are cultural tactics, such as changing the environment to be unsuitable for the pest. Then come physical and mechanical tactics, things such as screens, barriers, traps or plant removal. Next come the biological tactics. Introducing predators, parasites or other living organisms to combat the pests. Get the good bugs to kill the bad ones and restore the balance. Finally come the chemical tactics, such as the use of pesticides, like insecticides, herbacides, fungicides or other chemical controls. Part of the cultural tactics for the ALB is regulatory. The United States has placed an embargo on untreated wood shipping crates from China, and has requested that other materials such as plastic or cardboard be used instead. They have also requested using higher quality wood but this would be more expensive because the cheapest wood for building crates is wood that isn’t much good for anything else because it’s already been damaged by the beetles. The physical mechanical tactic for ALB damage is to identify the affected trees, chop them down, chip them up and burn the chips so that the beetles can’t spread further. A death sentence isn’t a happy outcome, but it’s the only way to save other trees that haven’t been invaded yet. The real problem with ALB is that there is no good way to control it. In its native range there aren’t any very important biological controls, predators or parasites. Because these things feed down deep inside a tree or a limb, it’s impossible to get any kind of insecticide into where it’s feeding. There is essentially no way to get to the larvae that is doing all the damage.
(BugMobile) Well thanks Jim! Like he said, there are no known natural predators to serve as biological control of ALB in the united states. We have already heard that there aren’t any effective chemical controls for this pest. However, there are other cultural options for the future. Let’s ride!!! Music “I Get Around, by the Beach Boys”. Entomologists and horticulturists are working to determine which species of trees is likely to resist the ALB. We already know they like Maple but we don’t know whether they like other valuable trees, such as oak or ash. But the scientists have to be really careful when studying these insects, so that they don’t let any get out. This is one of the trees, one of the ashes, they go ahead and harvest it and basically take all the leaves off. Now they have the stick and they will go ahead and start harvesting that. Everything that we harvest, as far as plant materials, go into an autoclave bag and it will be autoclaved at the end of the process so that it's sterile when it leaves here and then it gets incinerated at the animal incinerator on campus so that it’s destroyed. All the media gets bagged and autoclaved as well and then it gets dumped. So everything that leaves here, leaves here dead or cleaned up in some form so we assure that we don’t have an insect walking out on us. On the leaves here, on this side you will actually see sawdust and you will see it on these leaves as well. As they are drilling holes into the wood, they are pushing out their sawdust and the sawdust drops on the leaves and drops on to the lower branches and you see these large clouds of sawdust. All of that is sawdust from the beetles kicking it out as well, the larvae kicking it out. Asian Longhorned beetle, interestingly enough, the larvae push a lot of the sawdust out of the tree. So it seems to be a lot larger amount than you normally see. It basically girdled the whole way around from the insertion point. The insertion point was here. We inserted it and it has dug all the way around chewed all the way around here and around here before it entered. It entered there. The way the hole looks, it looks like it looks like it's probably up here somewhere which is what they standardly do. So, on some trees you’ll get this kind of girdling pattern, on others you won’t. Some they go directly in. The sugar maple seems to be very tasty this time of year.
(BugMobile) And thank you Jim!! Hey don’t let those guys out, we don’t want to have to deal with these guys like I've heard they've had to do in the big cities. In New York and Chicago for every tree removed they are trying to replace it with another species that won’t serve as a host for Asian Longhorned Beetle. Arborists also don’t want to replace them with all the same kind of tree. They want the population to be diverse so that all the replacement trees don’t get wiped out in case there is another disease or pest that targets a specific kind of tree. Research from Penn State and the Pa. Dept of Agriculture could help inform us of about just which variety of trees should be replanted. Wow, what happened to you.