Vespa orientalis

Human activities, particularly international trade and the effects of global warming due to climate change, are facilitating the widespread distribution of species worldwide. A prominent example of this phenomenon is the Vespa velutina nigrithorax, commonly known as the yellow-legged Asian hornet. Originating in Asia, this species entered Europe through France, first being identified in the department of Lot-et-Garonne in 2004. Since then, it has rapidly expanded in all directions, reaching as far as northern Spain in 2010, Belgium and Portugal in 2011, and Italy in 2014. In Europe, it has demonstrated a propagation speed across territories at an alarming rate of 78 km per year.

In certain regions, the Vespa velutina has witnessed a significant surge in nests, escalating from a few dozen to hundreds within a year and reaching thousands in a short span, with annual increases exceeding 50%. The consequences of this invasion extend beyond beekeeping, impacting health and agriculture. In areas with high nest density, it is a leading cause (70%) of health emergencies due to allergic reactions. Additionally, it inflicts substantial damage to agriculture by biting fruit for sustenance. In urban settings, over half of firefighters’ interventions are dedicated to eliminating these invasive hornets’ nests.

Adding to the concern, in the south and east of Spain, two other non-native hornets, namely the oriental hornet (Vespa orientalis) and the bicolor hornet (Vespa bicolor), have established themselves since 2018. The oriental hornet, present in North Africa and sighted in the Americas (Mexico and Chile), is suspected to be introduced through the movement of goods in ports.

Similar to its counterpart, Vespa orientalis builds cellulose nests and lives in a caste system. Its colonies are established by a fertile female after hibernation, with males and workers collaborating to provide for the colony’s needs. Unlike Vespa velutina, nests are typically built underground, in hollow trees, or cavities in walls, rather than in treetops.

The hornet’s peak population and activity occur in late summer/early fall with about 3 to 6 panels containing 600 to 900 cells, preying on other insects such as grasshoppers, flies, and bees. At apiaries, they can be observed hunting around hives in large numbers, causing significant stress to bees and potentially leading to hive collapse.

In addition to preying on insects, Vespa orientalis damages fruit crops by biting fruits, reducing their commercial value, and utilizing woody parts for cellulose in nest construction, leading to plant dehydration.

The sting of Vespa orientalis is painful, and the species is defensive near its nests. The fact that many nests are buried in the ground, often using mammal burrows, poses a danger to walkers or land workers who may inadvertently approach or step on the entrance, triggering a defensive response.

The examples of these non-indigenous hornets serve as a stark reminder of the consequences when animal species establish themselves in new territories. Their presence not only leads to the death of bees but also manifests in various societal, health, and economic challenges. The “One Health” approach proposed by veterinarians, doctors, and biologists among other professionals emphasizes a global perspective on health, acknowledging that these invasive species have far-reaching effects.

The example of the Vespa velutina and how it has been irreversibly established should alert society to the importance of surveillance. Despite the immense daily movement of goods, maintaining vigilance at borders is essential to prevent the entry of species that pose risks to public health, biodiversity, agriculture, and livestock.

In regions where prevention has proven ineffective, urgent measures are needed to implement a plan for monitoring and neutralizing nests. Beekeepers are often tasked with this responsibility, despite not being experts in pest control. Baited traps, while used in some places, are not specific to hornets and may capture unintended species (only 1-3% of what is captured in these traps are hornets). Therefore, control actions must employ appropriate equipment and safe methods to mitigate risks to operators and other forms of wildlife.