Murder Hornets, Really?

As if 2020 could get any worse, enter the “murder hornet”. Measuring around two inches, the Asian giant hornet is a particularly nasty variety. They have longer stingers than the honeybee and their venom is more toxic – and they can sting repeatedly.

Sadly, these predators are known to decimate honeybee colonies. A cool fact from National Geographic is that Japanese honeybees have learned to protect themselves by surrounding the hornets and cooking them alive through intense flapping that reaches temperatures of over 115 degrees Fahrenheit. Japanese honeybees developed this defense as they co-evolved with the Asian giant hornet in a common native habitat.

First spotted in the state of Washington last December, the Asian giant hornet is thought to have entered the United States through shipping containers. As an invasive alien species to the United States, our honeybees are defenseless against this hornet.

Stowaways and Hitchhikers

Human travelers and importers sometimes intentionally transplant species to new locations for food, economic, or environmental purposes, such as for use as biological control agents. Though such approaches should be approved by regulators, illicit trade in plants, seeds and wildlife is a significant problem in global trade. And if you’ve seen those adorable agriculture-sniffing beagles in airports, their job is to catch illegal importation of fruits, vegetables, animal products, soil and samples people try to stow in their personal baggage.

These are all vectors for the introduction of invasive alien species, but the much bigger cause of the spread of non-native species throughout the world is international shipping in global trade.

Alien species hitch rides on agricultural commodities, stow away in shipping containers, get ejected into new waters through the purging of ship ballast water or embed themselves in wood packaging materials, among other modes of unintentional introduction through shipping.

Invasive weeds threaten fishing livelihoods and trade in aquatic goods.

Not Wanted: Moths, Mollusks and Beetles

Cargo ships carry water as ballast. At the end of an ocean voyage, freighters jettison the ballast water they took on at the port of origin but in so doing, they can introduce a non-native and sometimes aggressive and invasive aquatic species like zooplankton into new waters at the port of destination. Other unwelcome travelers include aquatic plants, algae or small animals that attach themselves to the hull of a ship.

Growing up in Michigan, I recall the invasion of Zebra mussels, native to the Caspian Sea region of Asia, that were transported to the Great Lakes region through ballast water discharge. They quickly spread throughout the United States causing infrastructure damage and economic losses along the way, not to mention being unsightly along the Great Lakes beaches.

Asian gypsy moths are another example of a pest whose eggs are easily transported in international shipping containers. USDA’s Animal and Plant Health Inspection Service (APHIS) closely monitors incoming vessels from the gypsy moth’s native lands of Japan, China, Korea and Far East Russia. During the annual Asian gypsy moth infestation season, APHIS requires that vessels from high-risk Asian ports bound for U.S. ports provide pre-departure certifications that they are free of the moths. APHIS also inspects for moth egg masses on incoming ships.

The Asian longhorn beetle is anathema to many species of broadleaf trees in North America and Europe but is suspected to have been introduced through infested wood packing material made of unprocessed raw wood. Because of the pest risk, international standards have been developed to require heat treatment or fumigation of wood packaging materials used in international trade.

Coming and Going

Invasive alien species can present a major threat to biological diversity by disturbing native ecosystems and habitats, causing native species to decline. The introduction of foreign pathogens and infectious diseases poses a threat to livestock and human health. Trade is the route by which many invasive alien species are introduced to new environments, and ultimately, the disruption to agricultural productivity can end up costing hundreds of billions of dollars every year through lost opportunities to trade.

For example, rats transported on ships are estimated to consume as much as 50 percent of Madagascar’s annual rice production. Fruit fly infestations have spread rapidly in West Africa, devastating mango, citrus and other tropical fruit production for export. The spread of pig disease like the swine flu has required farmers to cull herds and sacrifice exports.

Invasive grasses can ruin pastures important to animal grazing. Harmful algal blooms like the “red tide” along Florida’s Gulf Coast can deplete oxygen in waters and release toxins that kill fish and make shellfish dangerous to eat. Beyond agriculture, invasive alien species have caused the spread of infectious diseases, hampering business travel and tourism, a key economic driver for many countries – just as we’re witnessing now with COVID-19.

Prevent Invasive Species without Unduly Restricting Trade

The Convention on Biological Diversity requires countries to prevent the introduction of invasive alien species, as feasible and appropriate, and to control or eradicate them if introduced.

Because the introduction of alien species occurs largely through trade, the measures governments take to prevent their introduction will – by definition – be trade restrictive to some degree. They often involve controls at ports of entry, appropriate use of quarantine and remediation procedures.

International conventions on biodiversity, plant protection, prevention of animal disease and related trade agreements, preeminently the WTO Agreement on Sanitary and Phytosanitary Measures (SPS), are designed to achieve the objectives of protecting plant, animal and human health without unnecessarily restricting trade. WTO members are encouraged to adopt the guidelines and recommendations developed in global bodies specializing in plant and animal health and to make best efforts to harmonize SPS measures to facilitate trade.

To achieve the twin goals of protecting against the introduction of harmful species while facilitating trade, governments need to have in place transparent standards and procedures based on evidence and science-based risk assessments. Regulatory authorities must have expertise and competencies at the borders as well as phytosanitary and veterinary infrastructure such as diagnostic laboratories and proper storage to conduct inspections at entry points. And, ideally, more governments will implement IT systems to ensure that SPS procedures and certifications are integrated with other border systems. Scientific and regulatory cooperation across agencies and across governments is critical for effective monitoring, prevention and control of the global spread of harmful invasive alien species, which is in everyone’s interest.

Where Trade and Nature Intersect

A 2017 study in the journal Nature Communications found that the problem of invasive alien species has continuously increased, with more than a third of all new introductions recorded between 1970 and 2014. Introductions of algae, mollusks and insects in particular increased steeply after 1950, mostly likely as a consequence of the growth of global trade.

The arrival of murder hornets on the west coast is just the latest reminder that increased trade volume, changes in trade routes, and the expansion of airport and seaport capacity around the world means having to deal with the unwelcome stowaways in global trade.

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