Cicada wasps

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Cicada wasps
Shape of a cicada wasp, female

Shape of a cicada wasp, female

Systematics
Class : Insects (Insecta)
Order : Hymenoptera (Hymenoptera)
Subordination : Waist Wasps (Apocrita)
Partial order : Voices (Aculeata)
Superfamily : Chrysidoidea
Family : Cicada wasps
Scientific name
Dryinidae
Haliday , 1833

Cicada wasps (Dryinidae) are a family of the Chrysidoidea . Many species are not yet known to have hosts , but it is assumed that the larvae of all cicada wasps are parasitoids of both round-headed cicadas (Cicadomorpha) and pointed head cicadas (Fulgoromorpha). The larvae initially develop endoparasitic in the body of the adult or larval cicadas, the last larval stage then lives ectoparasitically in a so-called dryinid sac. Before leaving the sack, the internal organs of the host animal are eaten, which then dies. In addition, cicada wasps also feed predatory on cicadas. Host animals and prey are grasped with the front legs that have been transformed into catch legs.

distribution

Cicada wasps are common all over the world. They live in all terrestrial habitats in which their host animals, the cicadas, also exist. These live in all habitats with plants, from the salt marshes of the North and Baltic Seas, over the high mountains to the tropics and subtropics . Cicadas colonize all habitats from the banks of the water to dry grassland and forests . In addition to the occurrence of the corresponding host plant (s), other environmental conditions such as the microclimate and the vegetation structure are decisive for the distribution of species in space and time.

description

The females of the cicada wasps are characterized by having a poison sting. Wingless or short-winged (brachyptere) forms are common in females. The antennae of both sexes are ten-membered and set near the frontal plate ( clypeus) . The wasps are only about three millimeters long. The forefeet (tarsi) of the females are transformed into catching organs that function similarly to the tentacles of the praying mantis . They are used to catch cicada larvae, on which the wasps lay their eggs. No or only a few males are known of many species, this is particularly true of the subfamily Gonatopodinae. Adult animals can usually be found from April to September, especially in midsummer. They are often rarely found, although the parasitization rates of individual leafhopper populations can be high.

Many females of the cicada wasp species imitate ants in their external appearance. This allows them to infect their hosts more easily. The hosts often live in close relationships with ants, which eat the honeydew they excrete. The hosts therefore do not recognize their enemies ( mimicry ).

Way of life

Reproduction and development

Cicada larva with "dryinid sack".

The females of the cicada wasps mainly catch smaller, still larval cicadas, but also adult animals in order to stab an egg into their body. To do this, they grab the cicadas with the fore tarsi converted into fishing scissors . A larva hatches from the egg and develops in the host's body (endoparasitic). The larvae go through four or five stages depending on the species. The larva of the penultimate instar breaks through the skin between the segments of the cicada body (intersegmental skin) and then becomes an ectoparasite. It is further protected by the sheaths of its first stripped larval skin ( exuvia ). A characteristic, so-called dryinid sack (see illustration) forms in which the larva lives until pupation . The old larva (4th or 5th larval stage) bursts the heavily swollen sac after about two to four weeks and spins a compact, silky, often two-layer cocoon on a plant or in the ground, in which pupation takes place. The puppet rest lasts another four weeks in summer. The overwintering usually takes place as an old larva or prepupa in the cocoon or as a young larva in the wintering host. However, some species of cicada wasps also spend their larval time entirely endoparasitic .

The substances secreted by the cicada wasp larva can interrupt the development of the cicada larva. Usually this does not reach the adult stage. If the development is not interrupted, the host's metabolism is reprogrammed to be “parasite-friendly”. The parasitization can cause significant changes in the aging cicada larva. It forms a lot of hemolymph and fat. The formation of the exoskeleton and the genital organs gonads are strongly suppressed. The larva is castrated as it were parasitically, which mainly affects male individuals, some of which assume female characteristics. In addition, there is often depigmentation of infected adult hosts, which then appear pale in color. In infested adult cicadas, apart from the formation of a dryinid sack, no further changes seem to occur. The last larval stage of the cicada wasps eats the internal organs of the host animal before leaving the sack, which results in its death.

Host animals

There seems to be a host specificity within the subfamilies of the cicada wasps; they only seem to infect certain families of cicadas. The Aphelopinae parasitize on the leaf and dwarf leafhopper families . The Anteoninae are invariably parasites of the dwarf cicadas, while the Dryininae prefer beetle cicadas and glass-winged cicadas and the Bocchinae small cicadas of the subfamily of the chirps . The Gonatopodinae parasitize partially in the spur- leaf cicadas , while others in the dwarf leafhoppers .

The individual species are seldom restricted to one host species, but often show broad oligophagy and only use one or a maximum of two families of cicadas. In England, for example, the cicada wasp Gonatopus sepsoides (= G. clavipes (Thunverg, 1827) var. Sepsoides Westwood, 1833) was raised from 16 different species from eleven genera of the chirp and for Dicondylus bicolor (= G. bicolor (Haliday, 1828 )) 17 hosts from eleven species of leaf hoppers have been identified as hosts in Europe.

nutrition

The females of the cicada wasps feed on the sugary excretions of the cicadas ( honeydew ) or the hemolymph (body fluid) and the cell tissue of their prey. The males usually do not eat anything, but honeydew is occasionally consumed.

Systematics

Subfamily Anteoninae: Anteon caledonianum , female
Subfamily Boccinae: Bocchus thorpei , female
Subfamily Dryininae : Dryinus koebelei , female

So far around 1400 species have been described worldwide, 110 of them from Europe and around 140 species from the Palearctic fauna area. The assignment of the sexually dimorphic sexes is often difficult and can only be justified reliably through breeding. It is therefore not uncommon for only the females to be determined.

Subfamilies:

Selection of European species:

literature

  • H. Bellmann (1995): bees, wasps, ants. Hymenoptera of Central Europe . Franckh-Kosmos, Stuttgart. ISBN 3-440-06932-X .
  • A. Guglielmino (2002): Dryinidae (Hymenoptera Chrysidoidea): an interesting group among the natural enemies of the Auchenorrhyncha (Hemiptera) . In: Denisia 4, NF 176: 549-556. ISBN 3-85474-077-8 .
  • J. Zahradnik (1985): bees, wasps, ants. The hymenoptera of Central Europe . Franckh-Kosmos, Stuttgart. ISBN 3-440-05445-4 .

Web links

Commons : Dryinidae  - Collection of images, videos, and audio files

Individual evidence

  1. ↑ Naamlijst Wespen en Mieren, Netherlands ( Memento of the original from August 27, 2011 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.nev.nl
  2. ↑ Naamlijst Wespen en Mieren, Netherlands ( Memento of the original from August 27, 2011 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.nev.nl
  3. ↑ Fauna Europaea - Dryinidae