By Ryan Hylton
Only one science topic has rivaled the Coronavirus pandemic in recent news cycles: the “Murder Hornet”. Although this nickname is a bit sensational, it does not fall far from the truth. Vespa mandarinia, or the Asian giant hornet, is the largest hornet species in the world and is known for its ability to decimate honeybee populations1. It not only kills the honeybees, it decapitates the adult bees using its serrated, pincer-shaped mandibles. Finally, the Murder Hornet brings the larvae back home for the hornet larvae to feed on2,3. Although V. mandarinia is native to Asia, in late 2019 this pest was spotted in North America1. Now scientists are trying to track it down and eradicate it before it can gain a foothold on the continent and devastate local honeybee populations.
V. mandarinia is the largest hornet in the world, reaching a length of nearly two inches1 (Figure 1). Its stinger is ¼ inch long and is capable of penetrating a beekeeper’s protective suit2. Besides their menacing appearance, the main problem they present is their ability to wipe out honeybee colonies. Although the giant hornets are generally solitary hunters, during the late summer and early fall they often hunt in groups1. Groups of Murder Hornets have been known to kill an entire hive of 30,000 bees in a few hours2,3. In Asia, honeybees have evaded extinction due to the sophisticated mechanism they possess for combatting the deadly hornets1,2,3. Often, hornets will act alone as scouts and identify a suitable honeybee hive to attack before recruiting other hornets to the fight. The honeybees will then spread pheromones that attract the scout hornet into the nest. Once this happens, worker bees swarm the hornet and begin vibrating their wings violently. Inside this ball of bees, the temperature increases to a toasty 114° Fahrenheit. This, combined with the spike in carbon dioxide levels kills the hornet invader.
Unfortunately, honeybees in North America (the European honeybee) have not evolved around V. mandarinia, and thus do not exhibit this ball-forming behavior1,2. This leaves them vulnerable to hornet attacks. Human-made solutions to preserving the bees are thus imperative, as honeybees enable the production of some 90 different agricultural crops through their pollination services1. Honeybee populations in North America have already been plummeting for a number of years. Since 2012, the bee population has been declined 29-45% each year1. The causes are multifold, including varroa mites, viral diseases, and agricultural pesticides1,2. If the Murder Hornet were to establish a home in North America, it could make this problem worse. However, scientists currently believe this is far from a foregone conclusion. Although there have been a handful of distinct sightings of Murder Hornets in North America, and the Pacific Northwest has a climate similar to their native one in Asia4, they have yet to make this continent home.
Murder hornets hibernate through the winter into late April. Since the first sightings of these pests were reported last year, people have been searching for hibernating hives in a desperate attempt to exterminate the hornets before they are able spread to other parts of the continent. If they spread beyond the Pacific Northwest, scientists believe it would be too late to eliminate them4. So, for now, the mood is one of cautious optimism. However, the race is on to find and eradicate this invasive pest before it makes a bad situation worse for American honeybees.