A world without wasps would be catastrophic for ecosystems and the global economy, The Independent
A world without wasps would be catastrophic for ecosystems and the global economy
The much-maligned insects are not only crucial in preventing certain plant forms from extinction; they also play an integral part in protecting farmers’ crops across the planet
They are one of the most unwelcome signs of summer. Buzzing through beer gardens, attacking innocent picnics, wasps arrive ominously with a sting in their tails. Universally disliked, they are swatted, trapped and cursed. But would a wasp-free world really be a better place?
Despite their poor public image, wasps are incredibly important for the world’s economy and ecosystems. Without them, the planet would be pest-ridden to biblical proportions, with much reduced biodiversity. They are a natural asset of a world dominated by humans, providing us with free services that contribute to our economy, society and ecology.
Wasps, as we know, turn up everywhere. More than 110,000 species have been identified, and it is estimated there are still another 100,000 waiting to be discovered. One recent study described 186 new wasp species in one small corner of Costa Rican rainforest alone. In contrast there are only around 5,400 species of mammals, and 14,000 recorded species of ant.
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This huge and diverse assemblage belongs to the order Hymenoptera and is divided into two groups, the Parasitica and the Aculeata. Almost 80,000 species of wasps belong to the Parasitica group, which lay their eggs in or on their prey or plants using elongated tubular organs called ovipositors. The remaining 33,000 species are Aculeates, most of which are predators, and the ones whose ovipositors have been modified through evolution to form a sting.
Both parasitic and predatory wasps have a massive impact on the abundance of arthropods, the largest phylum in the animal kingdom, which includes spiders, mites, insects, and centipedes. They are right at the top of the invertebrate food chain. Through the regulation of both carnivorous and plant-feeding arthropod populations, wasps protect lower invertebrate species and plants. This regulation of populations is arguably their most important role, both ecologically and economically.
Although the majority of wasps lead solitary lives, it is the 1,000 or so species of social wasps which make the biggest impression on insect populations. Social wasp queens share their nests with thousands of offspring workers, who raise upwards of 10,000 sibling larvae during the colony cycle. This means a single nest provides a whopping bang for buck in terms of ecosystem services, killing vast numbers of spiders, millipedes and crop-devouring insects.
Many social wasps are generalist predators too, which means they control populations of a wide range of species, but rarely wipe any single species out. This makes them an extremely useful, minimising the need for toxic pesticides, but unlikely to threaten prey biodiversity. It is not yet possible to accurately quantify their huge economic value in this regard, but their diet of agricultural pests such as caterpillars, aphids and whiteflies makes a massive contribution to global food security.
Wasps also play a crucial role in ecosystems as specialist pollinators. The relationship between figs and fig wasps is arguably the most interdependent pollination symbiosis known to man. Without one another, neither the fig nor fig wasp can complete their life-cycle – a textbook example of co-evolution which is estimated to have been ongoing for at least 60m years. Figs are keystone species in tropical regions worldwide – their fruit supports the diets of at least 1,274 mammals and birds. The extinction of fig wasps would therefore be catastrophic in tropical ecosystems.
Almost 100 species of orchids are solely reliant on the action of wasps for pollination. The plants mimic the appearance and chemical profile of female wasps, tricking males into attempting to mate with them, so that as the male wasps attempt to copulate with the flower they are loaded with pollen which is then transferred to the next male-seducing orchid. Without the wasp, these orchids would be extinct.
Wasps also function as generalist pollinators, inadvertently transferring pollen between flowers they visit for nectar collection. One type even provide their larvae with pollen instead of insect prey. These “pollen-wasps” are considered to perform the same ecological roles as bees, pollinating a diverse array of plants.
Unfortunately, while bees are credited with contributing at least €100 billion a year to the global economy through their acts of pollination, the works of wasps in the same sector is often ignored.
Even the wasps’ sting could have a positive impact on the human population. Medical researchers are exploring the potential use of biologically active molecules found within wasp venom for cancer therapy. A chemical found in the venom of the tropical social waspPolybia paulista, has been shown to selectively destroy various types of cancerous cells.
Since they protect our crops, make ecosystems thrive, sustain fruit and flowers, and might help us fight disease, perhaps we should appreciate the wonderful work of wasps before we next swipe at them with a rolled-up newspaper. They may be a nuisance on a sunny afternoon – but a world without wasps would be an ecological and economic disaster.
This article was first published in The Conversation. Seirian Sumner is a senior lecturer in behavioural biology and Ryan Brock is a master of research candidate at the University of Bristol
The Purpose of Wasps: Why Do We Need Them?
We all have an image of a wasp in our minds. And probably a few choice words to go along with it. But what do we really know about wasps?
There are over 100,000 wasp species worldwide, so we may not even all have the same image. Which is why here, we’ll cover the basics of wasps, the purpose of wasps, and the benefits of wasps for natural ecosystems and humans.
What Are Wasps?
All wasps belong to the order Hymenoptera, along with bees, ants, and several other insect species. While wasps seem similar to bees at first glance, they differ in body shape and nesting behavior and sport a wider variety of colors.
Bees have a rounded abdomen, however, wasps’ abdomens are pointed, and they have a narrower waist area between the thorax and abdomen. They also use chewed up wood fibers or mud to make a papery or concrete-like nest, while bees make nests from a wax that they secrete. Wasp colors range from yellow and black (like bees) to bright red and even metallic blue.
Did you know?
Only about 33,000 species of wasps sting, and of those, only the females have stingers.
There are two general groups of wasps, solitary and social wasps. And they all play similar roles in the various ecosystems to which they belong.
With over 75,000 species, solitary wasps are the largest of the two groups.
They are considered solitary because they don’t live in colonies. Some build nests while others nest underground or in wood, other plant matter, or the nests of other hymenopterans.
Most kill insects or spiders (using their venomous stingers) and bring them back to the nest to feed their larvae. The larvae of those that lay eggs in other insects’ nests (the parasitic wasps) simply feed on the larvae of their host or the food provided by the host parent.
Although social wasps make up a smaller proportion of wasps (only around 1,000 species), they are the most well-known. This group includes yellow jackets, paper wasps, and hornets.
Social wasps build colonial nests with a queen or queens, drones, and workers. As summer begins, the queen wakes up from hibernation and builds a small nest where she lays eggs. When the eggs hatch, she takes care of them until they become adult workers, feeding them insects and spiders. These workers then enlarge the nest that she started. As worker wasps build more and more nest cells, the queen continues to lay more eggs and the workers rear the larvae.
Social wasp colonies can reach over 5,000 members. When the colony has grown sufficiently, the workers preferentially feed some larvae more than others to rear new queens.
Social wasps build hanging nests or nests within cavities in trees or soil. When their nest is disturbed, they secrete a pheromone that alerts their fellow wasps and they swarm the trespasser. Unlike bees, wasps can easily free their stingers from a target and sting again. This has not helped their image.
The Importance of Wasps
The need for wasps can’t be overstated. If you’re wondering what do wasps do for the ecosystem then you’ve come to the right place.
They are important pollinators
They serve many crucial ecological roles, including pollination, pest control, and decomposition. In fact, one type of wasp singlehandedly keeps figs alive. Figs have an unusual, closed flower. In order to pollinate a fig, the fig wasp has to crawl inside the flower, where it deposits pollen and lays its eggs.
Wasps are also responsible for the survival of nearly 100 species of orchids, the flowers of which mimic female wasps so that male wasps will land on them, picking up pollen when they do. Wasps pollinate many other plants as well.
Only wasp larvae eat insects and spiders. The adults rely on nectar and aphid honeydew or other food high in sugar content, including a sugary fluid that larval wasps make.
As the larvae grow up, wasps must look farther afield for sustenance. Their search for sugar has made them the uninvited and unwanted guest at many picnics. However, as they travel from flower to flower picking up nectar, these beneficial wasps also collect and deposit pollen.
They are natural pest controllers
Wasps are natural pest control experts. As mentioned, they hunt and kill insects and spiders to feed their larvae. Solitary species usually focus on one type of prey, while social wasps are less picky. This likely makes social wasps more important for pest control as they will hunt a wider variety of pest species.
Wasp prey includes caterpillars, whiteflies, aphids, greenflies, and millipedes. Wasps hunt insects and spiders that eat other insects, those that eat plants, and even those that spread disease. This makes them invaluable population control agents for natural ecosystems, agriculture, gardens, and human health. They may even provide greater control than insectivorous amphibians, birds, and mammals.
And, since wasps multiply at rates that nearly mirror those of their prey, it allows them to keep up with pest populations.
They are good decomposers
Wasps also act as decomposers. In their quest for sugar, they come across rotting or rotten fruit, which they readily feed on, reducing waste within their ecosystem. If someone asks you are wasps good for the environment, you can confidently tell them about the ecological roles they play.
However, if you’re wondering if wasps make honey then the answer is no. Their nests are only used for rearing young.
The Future Value of Wasps
One potential benefit of wasps is derived from their most reviled trait: their sting.
Researchers in Brazil are testing the toxin in the sting of the wasp Polybia paulista. It appears to target cancerous cells while ignoring normal cells. In mice, this toxin attaches to molecules on the surface of cancer cells, breaking open and destroying the cells.
While we may not love wasps due to their ubiquity in the months when we want to enjoy ourselves outside, they are crucial to life as we know it.
They are just as important as bees in terms of pollination. They provide much-needed pest control services. They also may be another weapon in our arsenal against cancer. Before you swat one, think about how necessary they are, and maybe let it go on its useful way.