The spotted lanternfly, Lycorma delicatula, is a newer invasive species from Asia that has hit the northeastern United States since its discovery in 2014. Like many invasive species, it had to overcome many hurdles that would allow it to adapt and survive in a different climate and habitat. The spotted lanternfly came with a big advantage: the United States has its favorite home in 44 of the 50 states. Its secret? The tree of heaven, Ailanthus altissima, another invasive species from Asia.
Ailanthus, like so many invasive species, was purposefully introduced. Without any knowledge of the biology of tree of heaven, it makes sense. The trees have elaborate leaves in sets of 20 leaflets and dense, small flowers that make it a desirable ornamental tree. The tree also comes with a problematic advantage: allelopathy. They release chemicals in their roots that discourage other plants from growing there. Garlic mustard is another invasive species that has this adaptation, but native species like the black walnut also exhibit allelopathy. The problem is that only species that have adapted with them in their native habitat can deal with the deterrent chemicals.
Native Pennsylvania tree species are generally adapted to black walnut but not to garlic mustard and tree of heaven. As if allelopathy was not enough, the tree of heaven has another trick up its sleeve. Lots and lots of offspring. A female tree of heaven will produce thousands of seeds every year and both sexes produce root suckers if the tree is chopped down. So, this tree prevents native trees from competing and makes lots of offspring. After being introduced over 200 years ago, the tree of heaven has been able to spread extensively across the contiguous United States.
The tree of heaven is a formidable opponent to native trees and is well-distributed for easy access. Yet, how important is the tree to spotted lanternfly? Scientists are still a little unsure. The relationship is not like an anemone and clown fish that rely on each other for survival but perhaps more like a bee and the flowers it pollinates. For example, the European honey bee has many flowers that it can pollinate and collect nectar from, but it will tend to choose other flowers over others. The spotted lanternfly is the same way. It has been observed on over 70 tree species in its native and non-native range, but it tends to choose the tree of heaven to feed and lay eggs on.
As well, current research shows that spotted lanternflies may obtain toxic chemicals from the tree, making them unpalatable to predators. It seems obvious – the spotted lanternfly must need tree of heaven, right? In the spotted lanternfly’s native range in China, they survive in areas devoid of tree of heaven. Relationships in nature are never that simple it seems.
The spotted lanternfly and Ailanthus make quite the dangerous team, and their relationship is complicated to say the least. Hopefully scientists will understand the relationship between the host and insect in the upcoming years.
For now, current research from Penn State Extension shows that treating Ailanthus can help manage spotted lanternfly, so go check out their homeowner guide and pesticide tips online at www.extension.psu.edu/spotted-lanternfly. Contact your local extension office for more tips on management and research into Ailanthus and spotted lanternfly.
1. Ailanthus distribution map: https://www.eddmaps.org/distribution/usstate.cfm?sub=3003
3. Song, S., Kim, S., Kwon, S. W., Lee, S.-I., & Jablonski, P. G. (2018). Defense sequestration associated with narrowing of diet and ontogenetic change to aposematic colours in the spotted lanternfly. Scientific Reports, 8(1).
4. Urban, J. M. (2019). Perspective: shedding light on spotted lanternfly impacts in the USA. Pest Management Science, 76(1), 10–17.