Japan's Invasive Species Problem: Examining the Joro Spider

The issue of invasive species is frequently discussed across all biological taxa, particularly concerning species that impact ecosystems or agricultural, forestry, and fisheries industries, or those that pose health risks to humans. How to manage these species is a significant concern. Recently, certain species have garnered considerable attention. For example, in insects, the fire ant (Solenopsis invicta), which is highly venomous, the brown marmorated stink bug (Halyomorpha halys), which damages cherry and peach trees, and the yellow-legged hornet (Vespa velutina), which negatively affects beekeeping, are representative examples.

Among spiders, the Australian huntsman spider (Heteropoda venatoria) is well-known, but various other invasive species have established themselves in Japan. Through research and investigations, intriguing cases have been discovered, which this article will present.

## The Movement of the Australian Huntsman Spider: Transportation via Vehicles

First discovered in Osaka in 1995, the Australian huntsman spider was widely reported in the media at the time and quickly gained notoriety throughout Japan. Initially, its potent venom, capable of causing fatalities in those bitten, was emphasized, leading to its portrayal in the media as a "killer spider." However, over time, it became apparent that the probability of a severe reaction after a bite was lower than initially thought (no actual fatalities have been recorded in Japan). Consequently, it no longer receives as much attention. Conversely, given the potential risks to infants, elderly individuals, and those with allergies, it has been designated as an invasive wild plant and animal species. Eradication efforts and measures to prevent its spread are ongoing. The Australian huntsman spider has been found in 45 prefectures, excluding Aomori and Akita. However, the degree of establishment varies by region. Based on numerous recorded sightings, the primary driver of its distribution has been attributed to its ability to attach itself to vehicles and hitchhike. Information obtained from surveys of the Australian huntsman spider conducted at the request of local governments, among others, has confirmed that the species is indeed transported while clinging to vehicles.

Although the Australian huntsman spider is known for its potent venom, it rarely causes fatal bites in humans. However, a bite from an Australian huntsman spider can cause severe pain, and in severe cases, it can lead to symptoms like respiratory distress, hypertension, and increased heart rate due to its neurotoxin. Therefore, caution should be exercised when encountering an Australian huntsman spider; avoid touching or handling it. Children and the elderly should be particularly cautious to avoid being bitten.

The Australian huntsman spider prefers warm and humid environments and builds nests in low-lying areas. Therefore, it is crucial to be mindful of the surroundings and avoid approaching nests if discovered. If you encounter an Australian huntsman spider, contact your local government or environmental protection organization for appropriate action.