Language
Country/Area
No result found
Mysterious Spoiler: Why is Lymantria dispar listed as one of the top 100 invasive species in the world?
Lymantria dispar, also known as the tangled caterpillar or sponge caterpillar, is a species of moth belonging to the family Erebidae, native to Europe and Asia. Several subspecies of this species, such as L. d. dispar and L. d. japonica, have distinct features that make them easy to identify. This mayfly has been introduced to several continents and has become an invasive species in Africa, North America, and South America. Its larvae grow on many types of deciduous and coniferous trees and cause severe damage in years of mass reproduction. Due to these characteristics, Lymantria dispar is listed among the world's 100 worst invasive alien species.
"Lymantria dispar's name is composed of two Latin roots, of which Lymantria means "destroyer."
The origin of the name "tangled caterpillar" is unclear, but the term was used as early as 1832. Because some Roma communities consider "gypsy" to be a racial insult, in 2021 the Entomological Society decided to remove the name from the official name and proposed using "sponge caterpillar" as the new common name. The name comes from the French word "spongieuse," referring to the sponge-like egg mass formed when L. dispar lays its eggs. In Europe, however, the self-identified name "gypsy" has not prompted the same calls for change.
Taxonomy
The native European and introduced North American Lymantria dispar moths are considered the same subspecies, Lymantria dispar dispar. There is some confusion in the classification of this species. The USDA defines the Asian subspecies as "any female form of L. dispar that is capable of flight," although different subspecies may be capable of flight.
The European subspecies (Lymantria dispar dispar) is native to the temperate forests of western Europe and was introduced to the United States in 1869 and to Canada in 1912. The Asiatic subspecies (Lymantria dispar asiatica) is native to temperate Asia east of the Ural Mountains. Since the early 1990s, it has been found along the west coast of North America and has spread northward in southern Europe to countries such as Germany, where it hybridizes with the European subspecies, L. d. dispar.
Biological Pest Control Measures
Lymantria dispar was introduced accidentally in 1869 by artist and astronomer Étienne Léopold Trouvelot, who imported the species from Europe in an attempt to find a new source of silk to replace cotton, which was in short supply due to the American Civil War. Since then, various parasites and predators have been introduced as biological control agents to control this caterpillar. At least ten such species have become established in North America since the late 19th century, but there is a lack of regulation and research on the effectiveness of these natural enemies and their effects on non-target species.
"Some biological control agents have limited effectiveness against L. dispar and can affect populations of other native insects."
As a result, some of these generalist parasites have been less effective at controlling L. dispar and have weakened many large moth species that thrive in the Northeast, while another species attaches to L. dispar eggs. The parasitic wasp Ooencyrtus kuvanae has a clear effect on its own eggs, but it also parasitizes the eggs of other moth species. The most effective control agents were microbial pathogens: a virus (LdmNPV) and a fungus (Entomophaga maimaiga).
Current Situation in the United States
According to Scientific American, in June 2024, the severity of the outbreak in the Northeast and Midwest of the United States reached unprecedented levels, with caterpillar densities in many areas reaching more than 2,500,000 per hectare and 1,000,000 per acre. Some areas have been facing this problem for five years. Since the species was introduced into North America, L. dispar has caused significant ecological damage. Over the past century, its distribution has expanded at an average rate of 21 kilometers per year, resulting in the loss of 33 million hectares of forest between 1970 and 2013.
The U.S. Forest Service allocates about $30 million per year for control efforts. However, climate change has exacerbated the cycle of outbreaks, which usually occur every eight to twelve years, and are now becoming more frequent and having more dramatic impacts on the environment. The crown denudation caused by L. dispar would trigger the chemical defenses of the trembling tree, making it an unsuitable host tree for the Polyphemus caterpillars, further threatening its extinction.
The spread and destruction of this organism is particularly obvious, and we can't help but ask, how should we respond to the challenges of this ecological disaster in the future?
