Bedbugs between the curtains, in clothes, on the walls, it almost seems like an invasion. But where did they come from? And why there are so many?

The insect that we seem to find everywhere is the marbled brown bug, Halyomorpha halys, and it is an invasive alien species. Nothing to do with spaceships and laser beams; these are insects that are not where they should be: they were imported into a new environment which they found favorable for survival and reproduction.

Halyomorpha halys. Photo: Pixabay

First of all, some clarity on the terms.

  • A native species it is a species present in the territory not introduced by man.
  • A allochthonous species (alienates him) it is a species introduced by man, accidentally or intentionally, in a new territory, different from the area of ​​origin.
  • A allochthonous species (alienates him) invasive it is an alien species that causes damage to biodiversity, to ecological systems, to the economy and health of humans and other animals.

In Europe, alien species are approx 12000 and more than 3000 are located in Italy. Of the 12000 total species, around 10-15% is composed of invasive species. In addition to environmental damage, have a great economic impact: circa 12 billions of euros every year in the European Union alone.

They were introduced by man in places other than those of origin, mainly due to the increase in trade, travel and tourism. The main entry routes are ports and airports, where the movement of people and goods causes species to spread. Furthermore, are imported as ornaments, pets and for activities such as sport fishing, or it happens that they flee from farms and zoos or that irresponsible citizens release them into the wild.

What damage do invasive species do?

In short words, compromise the balance of an environment: they compete for the same resources as native species, they can alter the composition of those present in a certain area, they degrade the habitats they occupy and change the type of soil.

These species are considered to be the second major threat to Earth's biodiversity: contributed to the 54% extinctions of animals and continue to threaten the existence of many species present.

The impact on production activities is also significant. Among the effects are the devastation of crops, the loss of livestock and the destruction of river banks. Regarding health, they can transmit allergies or diseases, both to animal and plant species and to man.

Myocastor coypus. Photo: Pixabay

Returning to the dreaded bedbugs, the aforementioned invasive species is native to eastern Asia (China, Taiwan, Japan and Korea) and appeared in Europe in 2004. In Italy it was identified for the first time in 2012 and it quickly spread throughout the territory, becoming harmful to native bedbugs, the environment and crops, because it feeds on a great variety of plants. It is also suspected that it can cause respiratory allergies and contact dermatitis.

In the winter period, bedbugs gather in closed and sheltered places to overcome the cold and that is why we find them in the house.

In 2015 the average temperatures in Italy were higher than in the rest of Europe and this favored the survival of Asian bed bugs. In particular, in the Po Valley bedbugs reproduce twice a year, contrary to what happens in the rest of European places.

 

What can be done?

The answer is: prevention. It is easier to prevent the access of invasive species than to try to eliminate or contain them once established in the environment.

Europe has compiled a list of 49 invasive species whose introduction is prohibited, detention, breeding, cultivation, the Commerce, the sale, reproduction and release into the environment e 33 of these are present in Italy.

It deals with, eg, of the water hyacinth (Eichhornia crassipes), of the Asian hornet (Vespa velutina nigrithorax), of Louisiana red shrimp (Procambarus clarkii), of the American pond turtle (Trachemys written) and nutria (Myocastor coypus).

Pet owners included in the list, such as American pond turtles,

they had to report their possession to the Ministry of the Environment and explain the methods adopted to prevent its reproduction and dissemination. The zoological parks, botanical gardens and research centers can request special authorisations. For those who do not respect the laws, significant penalties are foreseen.

Procambarus clarkii. Photo: Pixabay

In the case of Asian bed bugs, the institutions are thinking of inserting the samurai vespa (Trissolcus japonicus) to decrease the number of harmful insects. It is a natural antagonist of the bed bug, it is a couple of millimeters long and lays its eggs inside those of bedbugs: when the larvae are born, they feed on the bedbugs in formation.

For the moment, the introduction of wasps was allowed only for study and research purposes; however, it is another alien species and the possible impact on the environment is not yet clear.

Trissolcus japonicus. Photo: U.S. Department of Agriculture

Sources:

https://www.researchgate.net/publication/309349778_Specie_aliene_invasive_il_caso_della_cimice_bruna_marmorizzata_Halyomorpha_halys_Heteroptera_Pentatomidae_in_Italia_e_nel_territorio_modenese

https://www.wwf.it/news/notizie/?uNewsID=37780

http://www.specieinvasive.it/index.php/it/

https://www.giornaledibrescia.it/italia-ed-estero/le-cimici-asiatiche-potrebbero-avere-le-ore-contate-1.3309174

http://entnemdept.ufl.edu/creatures/beneficial/wasps/Trissolcus_japonicus.htm