Let's learn to love wasps!
These underestimated insects are valuable pollinators. They can rid us of pests. Their venom could even help heal us.
Everyone loves bees. They are appreciated for the flavor of their honey, their collaborative work ethic and their valuable commercial pollination services. In a 2019 survey, 55% of those polled cited bees as the first species to save, ahead of elephants and tigers.
Our vision of wasps is very different. These unwanted guests who invite themselves to our picnics have been hated for millennia. Plutarch described them as degenerate bees. Our attitude towards the largest variety of wasp, the hornet (Vespa), is even more negative.
British tabloids are spreading scary stories about how an invasive species, the Asian hornet (Vespa velutina), is threatening honey production and pollinators in the country. For their part, the enormous but docile European hornets (Vespa crabro), continue to be persecuted - out of fear and ignorance - even as their numbers decrease, a phenomenon of which one hardly seems to care.
Is our judgment on this family of insects unfair? No doubt we are misinformed. Whole institutes are devoted to the study of bees, while research on vespids has stalled. As funds are limited, projects are rare and their results often misinterpreted by the press, which only reinforces our prejudices. There is nothing negative about what we have learned about wasps. Far from being unpleasant and aggressive, they have a beneficial role for ecosystems, the economy and even our health.
Without them, orchids would have disappeared from the planet
Take, for example, ecosystem services, a popular term for the benefits we get from nature. Bees are perhaps the main pollinators of many cultivated fruits, but it is wasps that, along with other insects, pollinate most wild flowers.
In fact, some plants are exclusively dependent on vespids, including a hundred species of orchids like the broad-leaved epipactis. These plants, which grow everywhere on the edge of forests, but never in large numbers, have a trick to attract pollinators.
Their flowers produce the same type of volatile chemical as that emitted by plants attacked by caterpillars, which deceives predatory wasps in search of prey. Thus, the wasps suck the nectar from the orchids and, slowed down by the soporific agents which it contains - undoubtedly the alcohol of the fungal contaminants -, they can collect more pollen. Without their tipsy pollinators, these beautiful plants would have disappeared from the surface of the planet.
Wasps benefit us even more directly: they are the third largest insect predator after birds and spiders. Using their powerful triangular jaws, they kill the prey they catch in plants or in the air. After cutting off the little nutritious wings of their victims, they take their dismembered bodies to the nest to feed their offspring.
Wasps' nests to protect cotton fields
It is estimated that at the height of the season a wasp colony captures between 3 and 000 prey per day. Their favorite targets are woodlice, spiders, flying beetles, and more rarely, butterflies and bees. They also quickly kill pests such as aphids, caterpillars, bedbugs and flies.
At the beginning of the XXth century, small nests of cardboard wasps were installed around the Caribbean cotton fields to stop the infestation of very voracious caterpillars, the worms of the cotton plant. Recent studies show that the wasps, which also bear the evocative name of Polistes satan, regulate the number of larvae of two of the world's largest pests, the sugar cane moth and the fall armyworm, which feeds on plants like corn.
The wasp sting can also be useful. Its venom is used to kill its prey, but social species also use it to defend itself. In addition, the protein-rich vespid larvae are one of the favorite foods of animals such as the ratel and the honey bee.
Their favorite targets are the underground nests. To protect themselves from bites while they extract the larvae, the ratels have stiff and bristly hairs on the muzzle and the crowded, scaly feathers around the eyes and the beak. As the defenses of predators have grown stronger, the wasp's venom has gained more power to keep them at bay.
Its venom destroys mouse cancer cells
This race to evolution has helped transform the wasp sting into a formidable weapon injecting on average 15 microliters of venom - a cocktail of bioactive molecules that varies according to the species. Among these molecules are histamines which increase blood flow, proteases and lipases which cause the destruction of tissues and blood cells, and neurotransmitters which overstimulate the nerves.
Humans may not be the target population of the wasp, but a single bite can cause a ping-pong-sized skin reaction, and many [simultaneous] go so far as to cause redness, nausea , vomiting, difficulty breathing and confusion. When a person is bitten by more than a hundred wasps, emergency care is required: there is no antivenom, but dialysis can remove toxins from the blood before they cause damage major organics.
Paradoxically, venoms often have medical applications. Several of their active substances are already promising. Thus, an extract from the venom of the Brazilian wasp Polybia paulista destroys cancer cells (at least in mice) by attaching themselves to lipids in their membrane. This extract is one of the components of the venom called “mastoparans” [a peptide toxin].
Another type of mastoparan is even more promising. As it also binds to certain lipids, it could be used to pierce the cell membrane of targeted tissues, either to destroy cells or to allow treatments to enter it. It also has encouraging antibacterial and antiviral capacities and blocks the development of the vector parasite of Chagas disease. Other components of the wasp venom are being studied to treat neurological conditions, allergies and cardiovascular disease.
Let’s stop demonizing them
What's more, wasps can play a role in preserving the environment. As they are affected by climate change, the practice of intensive farming and the use of pesticides which are at the origin of a large decline in insect populations, they can constitute a good indicator of environmental stress if the 'we manage to follow the evolution of their species.
To this end, the Big Wasp Survey was launched in 2017 in the United Kingdom. This is a citizen science project designed to collect data on the diversity and location of wasps by collecting specimens using traps placed in all gardens in the country and by comparing the numbers of species and individuals from year to year.
Our ignorance about wasps is still too great, but it is enough to overcome our prejudices to grasp the potential they can represent to overcome some of our biggest problems. Let’s stop demonizing them and learn to love them.
Richard Jones