How do invasive species enter new environments?

Invasive species are primarily introduced to a new place through four main pathways. One way is through the horticulture trade, which involves the import of plants that unknowingly bear pests. Ballast water from ships transports species or organisms from one port to another around the world. Another way is through the release of pets by pet owners who no longer want. One last way is through contaminated equipment that inadvertently spreads seeds and eggs to a new location.

Additionally, contaminated equipment represents another important vector. For example, boats can carry aquatic hitchhikers such as the larvae of Zebra Mussels between lakes. Construction equipment can have seeds in the soil. Hiking boots can distribute plant fragments over trails. When conducting field work, I documented the dispersal of Emerald Ash Borer beetles through the movement of firewood.

According to USDA reports, horticulture contributes to initial invasions approximately 65% of the time. Global shipping accounts for approximately 30% and is often attributed to contamination from cargo ships. The remaining 5% of invasions may arise from international mail parcels or travelers' luggage. I have intercepted seeds from international mail packages while conducting inspections at the port.

Preventing the introduction of new invasive species requires action by specific stakeholders. As an importer, you should request a phytosanitary certificate. If you're boating, you should clean your equipment between waterways to prevent the spread of invasive species. If you have a pet, consider using a surrender program. As a citizen, you should call the USDA SITC hotline on suspicious species. Your actions can block new invasions before they start.

Read the full article: Comprehensive Invasive Species List