Real wasps

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Real wasps
German wasp (Vespula germanica)

German wasp ( Vespula germanica )

Systematics
Class : Insects (Insecta)
Order : Hymenoptera (Hymenoptera)
Subordination : Waist Wasps (Apocrita)
Superfamily : Vespoidea
Family : Wasps (Vespidae)
Subfamily : Real wasps
Scientific name
Vespinae
Latreille , 1802

The real wasps (Vespinae) are a subfamily of the folded wasps (Vespidae) with 61 species worldwide. In Central Europe there are eleven species of real wasps, including the German wasp , the common wasp and the hornet .

Occasionally the field wasps , which are also state-forming, are counted among the real wasps. It is more common to combine the two groups as social wasps or, according to the preferred nesting material, as paper wasps .

features

Real wasps are physically similar to the rest of the wasps, but on average they are larger. An important distinguishing feature to the field wasps and solitary wasps is the structure of the abdomen, which in real wasps has a wide base, almost as wide as the maximum width of the abdomen, directly behind the constriction (the " wasp waist "). All Central European species show the wasp-typical black and yellow warning color , some species such as the hornet also have red or reddish brown tones. Real wasps form states or live as socially parasitic as so-called cuckoo wasps .

distribution

The real wasps are a relatively species-poor group that originally only occurred in Europe, Asia and North America. However, individual species have now also been introduced to South America, Australia and New Zealand. The genera Vespula and Dolichovespula are limited to the temperate zone and the subtropics. The genus Vespa has its main distribution in the subtropical and temperate zone of East Asia, but with a few species it penetrates the western Palearctic until Europe. The three nocturnal, uniformly yellow-brown colored species of the genus Provespa are completely restricted to the tropics of Southeast Asia .

Central European species

Genus Vespa ( hornets )

Genus Dolichovespula ( long-headed wasps )

Genus Vespula ( short head wasps )

Systematics

The division of the original genus Vespula Thomson in 1869 into the new genera Vespula and Paravespula by Paul Blüthgen is mostly rejected today. Paravespula is now only considered a subgenus of Vespula and is no longer valid as a generic name.

The relationship between the genera based on genetic characteristics is shown in the following cladogram :

 Vespinae 

Provespa


   

Vespa


   

Vespula


   

Dolichovespula





The genera Vespula and Dolichovespula (short and long-headed wasps) are therefore sister groups , whereby the monophyly of the genera is supported in the overall analysis, but their common clade is not confirmed in all individual analyzes. The genus Vespula includes 27 species, compared to 21 Dolichovespula species.

nutrition

Gallic field wasp . The part of the mouthparts, which is otherwise hidden in the rest position, is visible here through a drop of liquid held between the spread mandibles.

The mouthparts of the real wasps (and the closely related, in this respect indistinguishable field wasps ) are morphologically relatively unspecialized. In the basic plan, they consist of relatively short and strong, four-pointed mandibles and a labiomaxillary complex (made up of the fused and unified labium and maxillae ) in which the lobed glossae and paraglossae are relatively short and wide. In the resting position, the labiomaxillary complex is folded in and hidden behind the mandibles. The chewing and biting mandibles are used to acquire insect prey to feed the larvae, which is also divided and chewed . Real wasps prey primarily with the help of the mandibles, the poison sting is only used in exceptional cases. The mandibles also serve other purposes, such as gnawing off wood fibers to build the paper nest. The glossae and paraglossae serve as licking mouthparts. With them, carbohydrate-rich, liquid or liquefied food, for example nectar, is licked up. It also licks up body fluid that escapes when chewing prey. They also serve to exchange food when larvae and adults or the adult wasps feed each other (called trophallaxis ). In this way, the larvae can serve as food storage for the colony in order to bridge periods of low food.

Adult real wasps mainly eat nectar , pollen , stone fruits , plant saps, animal substances and insects. The larvae are fed with meat from dead or captured animals, and the food sources here are very diverse.

The wasp state

Nest building

Wasp queen in a new nest, with a few cells and a shield-shaped attachment to the nest shell

Wasp nests consist of a paper-like mass. The starting material for building nests is rotten, dry wood, which is chewed into pellets. The nests of the European hornet are open towards the bottom, the outer shell of the other wasp species is closed except for an entrance hole. They initially have five to ten cells, usually in a somewhat rounded honeycomb shape . At this stage they are looked after by the queen alone. They are then very similar to the nests of the field wasps, but differ in the approach of the nest shell, which is created from the beginning and not closed at the beginning. The nests later consist of several honeycomb levels arranged one above the other, which are always aligned horizontally and open at the bottom, and an insulating, multilayered outer shell. Usually the outer shell covers the honeycombs, which are only visible when the shell is destroyed. As the nest grows, the animals break down the shell when new combs are added below and close it again immediately.

Depending on the species, one can differentiate between “dark cave nests ” ( red wasp , German wasp and common wasp ) and those that hang their nests freely in hedges, trees, in attics. In the final stage, the nests vary in size depending on the population size that can be achieved. In Central Europe, only the two species, the German wasp and the common wasp, reach colony strengths of up to 7,000 animals. The other six state-forming species, on the other hand, only have a few hundred nest-inmates. The two groups are easy to distinguish by building a nest. The nests of the dark cave nests have an outer shell with semicircular insulating air pockets, and when viewed from above, a scale pattern emerges. The other species build tubular air pockets in the nest shell; this looks striated across. The nests of the dark cave can occasionally hang freely in larger cavities such as attics. But then they always sit wide with one or more sides on the base. The nests of the other species sit freely hanging on a small stem.

It is also possible to differentiate between the nests based on the construction material used. All real wasps build paper nests out of wood fibers. The hornet and the common wasp use rotten, decayed wood (from rotting tree trunks and branches). Their nest is light beige in color. All other species use wood that has been weathered on the surface ( dead wood on trees as well as on willow stakes, wooden fences in human settlement areas). Their nests are gray in color.

  • Paper-like flaky surface of a wasp's nest

  • Common wasp's nest with several floors

  • Honeycomb of a long-headed wasp nest

Establishment of the state

Several nests of the common wasp from different years built together in an attic

Real wasps are always statebuilding, whereby some species have also switched to a socially parasitic way of life. They form annual nests. The young queen, who founds such a state, lays an egg each spring in the first cells of the new nest she has built. Shortly before they are laid, she fertilizes the eggs with sperm from a semen bag in which she carries a sperm store from last autumn with her. She feeds the subsequently developing larvae with a pulp made from chewed insects. After feeding, the larvae give off a sugary drop , which in turn serves to nourish the queen and is the only way for the larvae to release liquid. Only shortly before pupation do the larvae give off feces. This prevents rotting in the nest due to contamination with excretions. Due to the pheromones exuded by the queen, no new fertile females develop from the larvae, but rather sterile workers. The workers hatched first then take over all further work with the exception of laying eggs. From this point on, the queen flies out less and less until she no longer leaves the nest at all and only devotes herself to laying eggs.

Organization of the wasp state

The wasp state is organized based on division of labor, the individuals are either busy building nests, cleaning cells, feeding larvae, caring for the queen or procuring food. The brood care is as intensive as with the bees . In contrast to these, the wasps do not have a waggle dance to communicate about the distance and direction of a possible source of food.

Due to the improved supply of the larvae, usually in special, larger brood cells, some larvae develop into fertile females, the queens of the next generation, in late summer or autumn. Males ( drones ) capable of fertilization develop from unfertilized eggs that were laid at the same time or shortly before, and die after mating. The males leave the nest and mate with a young queen from a neighboring colony, a behavior that counteracts genetic impoverishment through inbreeding .

Downfall and new beginning

The old queen dies in autumn and her wasp state then dissolves. When the cold snaps, the last homeless workers of the old state also die. Only the mated young queens show a different behavior and look for a hiding place protected against the cold. In a suitable microclimate such as rotten wood, in cavities, under bark or moss, they survive the winter asleep in a rigor known as diapause . The next spring, the young queen then founds a new state by starting to build a nest in a suitable place. Old nests are not repopulated.

Social parasitism

There are three social parasites among the native species , the cuckoo wasps . The females of these species invade the nests of a related species, kill the ancestral mother and take her place. Controlled by pheromones, the workers are induced to raise the offspring of the cuckoo wasp. At the end of summer the colony consists only of females and males of the cuckoo wasp species. There is no such thing as a worker caste. The cuckoo wasp species are very well adapted and can only be visually distinguished from their hosts with great difficulty, as there are only minor deviations in the front shield drawing.

Attack and defense

Sting of the German Wasp

The wasps use their sting to overwhelm and paralyze a possible insect prey or to ward off a troublemaker or attacker. In contrast to the bees, due to anatomical differences in the sting apparatus, they can stab as often as they want and inject their venom in the process. The sting reflex is still present even in animals that have been cut up or have just died.

Natural enemies

Hornet with a captured wasp
Wasp in the web of a garden spider

A natural enemy of genuine wasps is the European honey buzzard . He digs up the nests with his feet, breaks out the combs and feeds the larvae and pupae in them to his young. It protects itself from bites above all with its very dense and stiff plumage. But other insectivorous bird species also eat wasps, such as the red backed killer . Other natural enemies of real wasps include garden spiders , hornets , dragonflies and parasitic wasps, which lay their eggs in the wasps' larval chambers and whose larvae then kill the wasp larva as parasitoids .

Wasps and humans

The German wasp and the common wasp are solely responsible for the bad reputation that wasps have . These two species form the largest colonies (several thousand workers) and are the only ones that become intrusive towards humans and also attack human food (“plum pie wasps”). This is particularly the case when the nests dissolve in late summer and the workers who are still alive roam the area individually in search of food.

When a sting occurs , alarm pheromones are released that attract other animals and encourage them to sting. The poison causes an allergic reaction in some people . The dangers of a bite are explained in detail under Insect bite .

Introduction to New Zealand

After the German wasp was introduced from Europe to New Zealand around 1945, the common wasp was also found there at the end of the 1970s. It quickly became more common regionally and in some regions has almost completely displaced the German Wasp that had arrived before it. Common wasps are particularly common in New Zealand's southern beech forests. On the Südbuche endemic live scale insects of the genus Ultracoelostoma (Family Margarodidae), the very abundant honeydew produce, which serves the honey as food. The wasps reach an extremely high density and are not only food competitors for the honeydew for the native fauna, but also strongly decimate them as predators . The wasps reach an average frequency of 10,000 workers per hectare in the forests with a biomass of around 1000 grams per hectare, more than birds and rodents combined and two orders of magnitude more than all native wasp species. The nest density fluctuated strongly both regionally and temporally, but with an average of around 12 nests per hectare, it is considerably higher than in Europe (in England on average around 0.1 to 1.7 nests per hectare). Control examinations of previously examined forests revealed a massive decline in the native arthropod fauna . Due to the availability of food in winter, the nests of the common wasp can also overwinter there, unlike in Europe. Apparently this happens less often than with the German Wasp.

To limit this ecological impact, attempts are being made to control the invasive species in New Zealand. So the parasitic wasp Sphecophaga vesparum , a parasitoid of the wasps, was introduced and released. The species is established, but has not led to a sharp decline in the population of wasps, which are also infested by antagonists native to New Zealand without becoming rarer. Therefore, a fight with poison baits (the insecticide fipronil in protein baits ) is tried. In spite of the significant decline in the wasps population, they have so far not been sufficient to regenerate the natural fauna.

literature

Web links

Commons : Wasps  - album with pictures

Individual evidence

  1. ↑ Federico Lopez-Osorio, Kurt M. Pickett, James M. Carpenter, Bryan A. Ballif, Ingi Agnarsson (2014): Phylogenetic relationships of yellowjackets inferred from nine loci (Hymenoptera: Vespidae, Vespinae, Vespula and Dolichovespula). Molecular Phylogenetics and Evolution 73: 190-201. doi: 10.1016 / j.ympev.2014.01.007
  2. ↑ Volker Mauss, Kenneth Kuba, Harald W. Krenn: Evolution of the multifunctional mouthparts of adult Vespinae. Chapter 14 in: Harald W. Krenn (editor): Insect Mouthparts. Form, function, development and performance. Springer, Cham 2019. ISBN 978-3-030-29653-7 .
  3. ^ William Horace Williams: Lessons in Nature . Volume 1. Educational Publishing Company, 1915.
  4. ↑ Eric A. Macalintal, Christopher K. Starr: Comparative morphology of the stinger in the social wasp genus Ropalidia (Hymenoptera: Vespidae). Memoirs of the Entomological Society of Washington Vol. 17, 1996, pp. 108-115.
  5. ↑ Lorraine Mulfinger et al .: Sting morphology and frequency of sting autotomy among medically important vespids (Hymenoptera: Vespidae) and the honey bee (Hymenoptera: Apidae). Journal of medical entomology February 29, 1992, pp. 325-328.
  6. ↑ a b J. Beggs (2001): The ecological consequences of social wasps (Vespula spp.) Invading an ecosystem that has an abundant carbohydrate resource. Biological Conservation 99 (1): 17-28. doi: 10.1016 / S0006-3207 (00) 00185-3
  7. ^ CD Thomas, H. Moller, GM Plunkett, RJ Harris (1990): The prevalence of introduced Vespula vulgaris wasps in a New Zealand beech forest community. New Zealand Journal of Ecology 13 (1): 63-72.
  8. ^ ND Barlow, Jacqueline Beggs, Mandy C Barron (2002): Dynamics of common wasps in New Zealand beech forests: a model with density dependence and weather. Journal of Animal Ecology 71 (4): 663-671. doi: 10.1046 / j.1365-2656.2002.00630.x
  9. ↑ DM Leathwick, PL Godfrey (1996): Overwintering colonies of the common wasp (Vespula vulgaris) in Palmerston North, New Zealand. New Zealand Journal of Zoology 23: 355-358.
  10. ^ JR Beggs, RJ Harris, PEC Read (1996): Invasion success of the wasp parasitoid Sphecophaga vesparum vesparum (Curtis) in New Zealand. New Zealand Journal of Zoology 23: 1-9.
  11. ↑ PJ Lester, MAM Gruber, EC Brenton-Rule, M. Archer, JC Corley, L. Dvořák, M. Masciocchi, A. Van Oystaeyen (2014): Determining the origin of invasions and demonstrating a lack of enemy release from microsporidian pathogens in common wasps (Vespula vulgaris). Diversity and Distributions 20: 964-974. doi: 10.1111 / ddi.12223
  12. ↑ Eric Edwards, Richard Toft, Nik Joice, Ian Westbrooke (2017): The efficacy of Vespex® wasp bait to control Vespula species (Hymenoptera: Vespidae) in New Zealand. International Journal od Pest Management 63 (3): 1-7. doi: 10.1080 / 09670874.2017.1308581
  13. ↑ JR Beggs, RJ Toft, JP Malham, JS Rees, JAV Tilley, H. Moller, P. Alspach (1998): The difficulty of reducing introduced wasp (Vespula vulgaris) populations for conservation gains. New Zealand Journal of Ecology 22 (1): 55-63.