This photo shows Lari beetles (Laricobius nigrinus) eating hemlock woolly adelgid (hwa) in the Daniel Boone National Forest (10-17-2019). Lari beetles only eat hwa, and they eat a lot of them! These little beetles give us a lot of hope as we work to save Kentucky's hemlock forests.
The hwa in this photo are coming out of dormancy and will soon become active adults. As the hwa feed on the hemlock tree, they exude a white "wooly" substance. This waxy substance makes it easy to tell if a hemlock tree is infested. Go Lari go!
Biological Control: Introducing predatory insects
If hemlocks are to remain in our forests, insecticide treatments will not be enough. We cannot afford to treat every tree, or even most trees. And if we could, it would still be necessary to retreat trees in perpetuity. In the long term, it will be necessary to change hemlock-HWA ecology in some way that allows adelgids and hemlocks to coexist. New, rapidly developing gene editing technologies are promising, and one could imagine a number of ways that they might be applied to save hemlocks. Unfortunately, those tools are not available to us at present, and there is no way to know when, or if, they will be.
For now, our best option is to continue the careful introduction of insects that prey on the hemlock woolly adelgid. In East Asia and the Pacific Northwest, adelgids feed on hemlocks but very rarely kill trees. This is most likely due to a combination of sufficient numbers of organisms for whom the adelgids are prey, and physiological adaptations in the trees themselves that make them better able to tolerate the adelgids.
Research into the mechanisms of chemical and physiological resistance to HWA is ongoing. In the meantime, release of predator insects is underway. In fact, millions of individual predator insects have been released. Read more about the individual species in the gallery below. Click the picture for info.
For now, our best option is to continue the careful introduction of insects that prey on the hemlock woolly adelgid. In East Asia and the Pacific Northwest, adelgids feed on hemlocks but very rarely kill trees. This is most likely due to a combination of sufficient numbers of organisms for whom the adelgids are prey, and physiological adaptations in the trees themselves that make them better able to tolerate the adelgids.
Research into the mechanisms of chemical and physiological resistance to HWA is ongoing. In the meantime, release of predator insects is underway. In fact, millions of individual predator insects have been released. Read more about the individual species in the gallery below. Click the picture for info.