Cat eats mouse, lion eats gazelle. So far nothing new: it’s nature, beauty. But if someone raises an octopus, puts it on a patrol boat and takes it offshore with the more or less declared mission of killing a crab, then the food chain begins to resemble a military operation.
That’s what’s happening in theAdriatic. In June and then again in August, off the coast of Cesenatico and Riccione, young octopuses raised by theUniversity of Bologna within the scope of Octo-Blue project. The enemy is Callinectes sapidusthe American blue crab which in recent years has caused a massacre of clams, putting fishing and aquaculture in difficulty. The octopus, for its part, does not seem impressed by the invader’s CV and when faced with a good-sized crab, it acts like an octopus: it grabs it and eats it. Now we need to understand if in the open sea it will really be able to impact the population of the alien crustacean with extraordinary fecundity: a single female can produce between 2 and 3 million eggs for each single deposition. But reinforcements are arriving.
The pincer maneuver between the open sea and lagoons
This summer, in the lagoons of Sabaudia and Caprolace, researchers observed that young mullets they eat the larvae of the blue crab. In short, the plan could include an attack on two fronts: octopuses against adults, mullets against newborns. A pincer maneuver.
The old idea of pitting one species against another has produced some of the most spectacular stories in applied ecology. The dragonfliesfor example, are natural candidates against mosquitoes. When they intercept them they devour them, but the larvae do the bulk of the work. A meta-analysis of 31 studies released on Journal of Animal Ecology estimated that a single dragonfly larvae can eat on average about forty mosquito larvae per day.
Then there’s the samurai waspKurosawa’s film name for a hymenoptera a few millimeters long. Scientific name Trissolcus japonicusis released against the Asian bedbugHalyomorpha halys, the one that wasn’t there before and today can be seen massacring our pears, apples and kiwis, entering houses in droves, displacing the more familiar green bug (the Asian one is grey-brown with spider-like legs). Well the samurai wasp lays its eggs in those of the bedbug and prevents its development. In Emilia-Romagnaaccording to a report from the Region, after the launches that began in 2020, it has established itself permanently, even if we are not yet at the unconditional surrender of the bug.
From the Tuscan forests to the extreme scenarios overseas
The chestnut already has its samurai. When the small Asian gall wasp, Dryocosmus kuriphilusbegan to devastate Italian chestnut groves, was introduced Torymus sinensisanother Asian parasitoid. In many areas it has reduced the infestation to low levels. However, 2026 has reminded us that victories in ecology are rarely definitive: the problem has returned in various areas of the world Tuscany.
In the United States the entomological imagination has produced something even more pulp: decapitating flies of the genre Pseudacteonissued against fire ants imported from South America, harmful to our health and biodiversity. The female Pseudacteon lays an egg in the ant’s thorax, the larva migrates towards the head and, having reached the end of development, releases an enzyme that dissolves the connective membrane. Before the head comes off, the ant wanders confused out of the nest. Then the head detaches from the torso and the fly uses it as a “cocoon”. I mean, not really a Bambi-type scene, but that’s the reality of those control programs. By the way, recently, the fire ant made its appearance in Sicily.
Then there is the lawnmower with fins: the grass carpused throughout the world as an ecological and economical alternative to chemical herbicides to clean irrigation canals and artificial lakes infested with algae and plants. To prevent the remedy from becoming another invasion, sterile specimens are now often used: too many carp also shave the plants that were wanted to be preserved.
Large predators and forest balance
And the wolves? Here, our way of dividing animals into “good” and “bad” becomes curious. For a young fir or oak, the tender fawn can be a bulldozer: it eats shoots and debarks the trunks. In the western Italian Alps almost 80% of young trees are damaged by ungulates. Dries Kuijperecologist of Polish Academy of Sciences who studies wolves in the Białowieza Forest, explains: «Our experience is that the presence of these animals definitely favors the growth and regeneration of the forest». And he adds: «Wolves don’t just kill animals. They change the entire functioning of the ecosystem for the better.” In short, they are the protectors of the woods. Ah but of course, the wolf can also attack flocks. Which would then be his job. The problem can be solved with sheepdogs: in the project Life Medwolfin the Grosseto area, this measure halved the number of animals killed. And in a study in Southern Italy, wolves retreated without prey in 98 percent of attack attempts if sheepdogs were present.
In biological control the use of natural antagonists is therefore widespread. We could continue with the cute ladybugs, used to devour aphids (plant lice) and scale insects. Instead, against mites and small caterpillars, the intervention of lacewings, or rather their ravenous larvae, is invoked.
The risk of paradox and the climate variable
At this point the game seems perfect: an invader arrives, you look for his natural enemy and send him to the front. Too bad it’s full of stories that end badly. In Australia The cane toad it was introduced in 1935 to eat beetles that damaged sugar cane. The beetles remained, the toad thrived and began to poison many native predators with its toxins.
In Hawaii the mongooses they were imported in the nineteenth century to eliminate rats from plantations. But rats are mostly nocturnal, mongooses diurnal. When they went for a walk they rarely met. Thus the mongooses fed on the birds that nested on the ground.
And the gambusia fish? It has been introduced into closed waters to feed on mosquito larvae, reducing the spread of diseases such as malaria. They chose it in Haiti after the earthquake, for example, but also on the estate of Castel Porziano in Rome in the 1960s, where it was necessary to combat pockets of anophelism. The outcome has always been the same: gambusias work with mosquitoes but consume the environment (in Rome they noticed a notable deterioration in water quality and the disappearance of numerous amphibian species).
Modern biological warfare also arises from these disasters. Today it is not enough to know that A eats B: we need to understand what else A will eat, whether it will reproduce without control and which non-target species it will affect. In Europe there are an estimated 12 thousand exotic species, of which 10-15% are invasive. On a global scale, theIpbes (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services) has more than 37 thousand established outside their range, over 3,500 with documented impacts. The global economic cost of biological invasions already exceeded $423 billion per year in 2019. Now, climate may shift the balance of power even further. Higher temperatures can break down barriers and lengthen the activity season of invasive insects such as the tiger mosquito.
If you want to see how an invasion ends when the right predator isn’t there, just go to Florida. The Burmese pythonnative to Asia, has reduced wildlife by 90% by attacking mammals, birds and reptiles. The main route of arrival was the trade in exotic animals, followed by escapes and liberations. Or go to Ibiza, where the horseshoe snake lives after arriving clandestinely from North Africa along with ornamental olive trees. Consequence: the Pithyusae lizardan endemic species, is driven to extinction.
Behind almost all these stories there is always the same species: Homo sapiens. What moves, what matters, what sometimes causes damage. But against many invasive animals a countermove can be found. Against the idiot who releases the exotic animal into the ditch, we are disarmed.
