WRITING HISTORIES OF CLIMATE CHANGE

When scrolling through social media or listening to the news regarding climate change and other horrible environmental changes brought about by climate change, it is easy to fall into a mindset of doom and gloom – that all of these changes are inevitable, and we are already past the point of no return. Many sources of news deliberately frame certain problems in this way to grab the attention of their audience and while some issues do warrant appropriate urgency, there are still examples of steps being taken in the right direction – and these efforts might not be futile! As the damage done to hemlock trees by hemlock woolly adelgid (HWA) seems progressively irreversible, there are still some researchers out there trying everything they can to slow the spread and save the trees. One of these researchers is Mark Whitmore, a forest entomologist who serves as the director of the New York State Hemlock Initiative (NYSHI).

Mark Whitmore has most recently led the project in a new approach to curbing HWA populations which makes use of biocontrols rather than other treatment methods such as insecticide usage. Biological control, or simply biocontrol, is the use of some sort of natural predator or pathogen to keep certain pests under control. The major drawback of insecticides that biocontrols do not have is the difficulty in spreading them. In order to treat an area that is infested with HWA, researchers have to treat every individual affected tree, which is timeconsuming and imprecise. It also is not an indefinite solution as the insecticides cannot protect the trees forever; after a certain number of years the trees would have to be retreated unless the HWA are completely eradicated from the area. Instead, researchers can introduce a natural predator to the HWA, in this case the beetle Laricobius nigrinus, and over time the beetles can eat the HWA and grow their own population to control HWA populations. In the past year, Whitmore has already led teams to treat several HWA-infested areas with L. nigrinus and the populations will be closely monitored over the coming years to see the progress. In total there have been 21 sites where L. nigrinus have been introduced since 2008.

The reason L. nigrinus are great biocontrols for HWA is that they are specialist predators, that is, they exclusively feed on HWA. This means that there is little to no risk that these beetles end up severely changing the ecosystem other than to decrease HWA populations. The life cycle of these beetles also aligns very well with the aestivation period of HWA so that they are even more effective at predating on HWA than other potential biocontrol candidates. At some of the sites which were treated years ago, they found evidence of L. nigrinus establishing themselves in the forests in 5 of the 21 sites, and this number is likely to continue to increase in the coming years.

Despite how far the spread of HWA has already reached across the United States and especially the northeast, people such as Mark Whitmore are still hopeful that the spread can be slowed and eventually stopped. Whitmore's HWA biocontrol project serves as much more of a long-term solution to the spread of these invasives, which could mean the revival of hemlock stands in the northeast on their last legs (or roots) and the conservation of hemlocks not yet affected by HWA. And if these experiments are successful, there is a great chance that these beetles could be used in forests across the country with HWA infestations. There is still hope in this battle to save such a keystone species in northeastern forests, and luckily there are many passionate people working to keep that hope and the hemlocks alive.

References:

https://blogs.cornell.edu/nyshemlockinitiative/
https://www.adirondackexplorer.org/stories/battling-the-hemlock-woolly-adelgid