Alien or allochthonous parasites . These terms indicate all those insects which, for reasons mainly attributable to human action, find themselves colonizing a territory other than the area of ​​origin.

In recent years, the invasion of alien species – which can act undisturbed because they are not opposed by their natural enemies, absent in the destination ecosystem – has become a real scourge for Italian agriculture . 

Alien insects, the most feared species

Here is a list of the most prolific, harmful and consequently feared alien insects on our territory.

• Asian bedbug

The Asian bedbug ( Halyomorpha halys ) is also known as the marble or Chinese bedbug. Originally from China and Japan, it was found in the Modena area in 2012 in very few specimens. From there it began to spread mainly in the orchards of the Po Valley and then, gradually, throughout Italy. Highly polyphagous, it causes extensive damage to fruit and horticulture . The particular resistance to insecticides, as well as the high mobility, make it an insect difficult to control.

• Popilia japonica

The Japanese beetle Popilia japonica is extremely voracious. It feeds on many species of agricultural value, including corn . Present in the United States, China, Russia and Portugal, this insect arrived in Italy, in the Ticino park, in 2014. Since there are no natural predators that keep the population low in Japan,  Popillia japonica  is spreading in a worrying way in many regions , despite the intervention of the authorities. It causes very serious damage from erosion on crops such as grapevine, rose , peach, pear, plum, hazelnut .

• Cinipida of the chestnut tree

The  chestnut beetle  (Dryocosmus kuriphilus) is a hymenoptera of Asian origin that attacks the shoots of many plants , proving particularly harmful to the chestnut. It makes its appearance in Europe in 2002, when it begins to attack Piedmontese chestnuts. Today it is effectively countered with biological control, using the parasitoid Torymus sinensis .

• Xylella fastidiosa

Xylella fastidiosa is an alien microorganism well known in Italy due to the epidemics that in recent years have involved the olive trees of Salento. The bacterium – officially present in Italy since 2013 – lives in the xylem vessels of plants. By producing viscous substances, it clogs these vessels and thus causes the plant to die. To date, there is no cure.

• Tomato moth

Tuta absoluta ,  also known as tomato moth , is an insect native to South America. Its presence has been found in Italy, particularly in the southern regions, since 2008. Parasite of the order of Lepidoptera, it has caused serious damage to tomato crops, especially in the first years after its appearance.

• Small fruit gnat 

Drosophila suzukii is an insect from China. He is attracted to ripe fruit – cherries , strawberries, apricots and peaches – where he lays his eggs. It made its first appearance in 2011 in Emilia Romagna.

• Fire blight

Erwinia amylovora , or fire blight , is a microorganism that causes tree leaves to dry out quickly . Originally from North America, it has been present in Italy since 1990. It attacks many fruit plants ( primarily apple and pear) and ornamental plants of the Rosaceae family.

• Eastern fruit fly

The eastern fruit fly ( Bactrocera dorsalis ) represents a recent threat to Italian orchards, given that the first findings in Italy date back to 2018. It is an insect native to tropical Asia, capable of attacking over 400 species of fruit and vegetables , causing them serious harm.

• Red-necked cerambicide

The red-necked cerambicide ( Aromia bungii) is a beetle native to China, present in Italy since 2012. The female lays her eggs under the bark of trees. Once hatched, the larvae dig long tunnels inside the trunk causing serious damage to plants such as cherry, peach, apricot and plum .

• Aethina tumida

The Aethina tumida is a beetle native to South Africa and present in Italy since 2014. It infests the hives of the honey bee , digging tunnels in the combs that often compromise the colony. 

• Red awl

The red weevil ( Rhynchophorus ferrugineus ) is a large parasite, native to southern Asia, which made its appearance in Italy in 2004. Specific microorganism of palms , it is highly prolific. It carries the infested palms – which show no signs of attack until it is too late to intervene – to death.

Invasions of alien insects, an anthropogenic responsibility

Real invasions, often out of control. But what are the main causes of the accidental introduction of alien insects into ecosystems?

The greatest responsibility is to be attributed to the growing international trade , able to carry parasites together with goods.

In fact, it is not uncommon for the ballast water of ships from exotic countries, food products grown in non-European countries, exotic ornamental plant species to become vectors of pathogens or parasite larvae.

From there to the proliferation and colonization of new areas, the step can be dramatically short.