Evaniidae
Encyclopedia
Evaniidae, also known as the ensign wasps or hatchet wasps, is a family of parasitic wasp
s. It numbers around 20 extant genera
containing over 400 described species
, and is found all over the world except in the polar region
s. The larva
e of these solitary wasps feed on cockroach
es and develop inside the egg-cases (ootheca
e) of their hosts.
attached very high above the hind coxae
on the propodeum
, and the metasoma
itself is quite small, with a long one-segmented tubelike petiole
, and compressed laterally over most of its length (segments 2-8). The ovipositor
is short and thin. When active, these wasps jerk the metasoma up and down constantly, as referenced in their common name
s. The mesosoma
is high, short and heavily sclerotized
, with a ridged and pitted surfact. The head is largely immovable and attaches to the metasoma on a short neck, with usually 13-segment
ed antennae
that do not differ between males and females.
Apomorphies of ensign wasp wings
and their venation are:
es. But good host data is only known for a fraction of this family, about 4% as of 2008, and thus it is likely that more unusual life history
strategies exist. Host specificity and coevolution with roach lineages seems to have played a significant factor in the evolution of some ensign wasp lineages. Others are less discriminating in their host choice and will attack almost any ootheca of a particular size.
The female wasp lays an egg inside the roach ootheca
(egg case), and the wasp larva hatches quickly and consumes the roach eggs. Technically, they are thus predators, rather than parasites or parasitoid
s as other parasitic wasp
s. A single egg is laid per ootheca, into a host egg in some Evaniidae, and between the eggs in others. Some are able to oviposit even when the female cockroach still carries the fresh ootheca around, while other ensign wasps will only attack oothecae that are completed and have been dropped by the mother roach. The wasps seem to be able to determine if an ootheca is already used to host a larva, and refrain from depositing eggs in such cases; alternatively, the larvae might be cannibalic, with the first to hatch in an ootheca eating any wasp eggs subsequently deposited.
Two Evaniidae species
, Evania appendigaster and Prosevania fuscipes, have achieved an essentially worldwide distribution nowadays, having been introduced along with various Blattidae
species of genera
Blatta
and Periplaneta
. While they do feed on insects that are considered pests, they rarely attain population size
s sufficient to act as effective biocontrol
agents. As cockroaches are typically more abundant in and around human settlements, Evaniidae are a regular sight in such habitat where many other wasps are absent, and are frequently encountered in buildings looking for prey. The adults drink nectar from flowers and neither they nor the larva
e are dangerous or harmful to humans.
" for any parasitic wasp
with unusual morphology. Among these were the more apomorphic and less diverse (but about equally speciose) taxa now placed in the Aulacidae
and Gasteruptiidae
, which together with ensign wasps make up the superfamily
Evanioidea. These were formerly a part of the paraphyletic "Parasitica", ranked as an infraorder. But the parasitic wasp lineages are not more closely related among themselves than they are related to unparasitic wasps, and thus the "Parasitica" are an obsolete group.
Rather, the Evanioidea seem to be close relatives of the Megalyroidea, Trigonaloidea, and particularly the Ceraphronoidea
. These four superfamilies seem to make up a clade
, which could be considered one of several infraorders to replace the superseded "Parasitica".
can be divided into one larger and four smaller groups, which might be considered subfamilies. Some genera
are hard to place in these though; they probably represent minor lineages of a more basal position. The groups, with genera sorted according to the presumed relationship, are:
and, presumably, ecology
. The fossil record, in particular from fossil amber
, is quite comprehensive, with about 10 genera and twice as many species known from the Late Jurassic
right up to a few million years ago. The primitive Mesozoic
genera Andrenelia, Botsvania and Praevania are only tentatively identified as Evaniidae at present; the first was once separated as family Andreneliidae.
Evaniidae seem to have undergone significant evolutionary radiation
in the Cretaceous
; these taxa were separated as Cretevaniidae, but seem to be a subfamily if anything. The main lineages of extant ensign wasps probably were well separate by the mid-Paleogene
. Few Evaniidae have been found in deposits dating from the Paleogene however, and the ancestry of the living genera consequently remains not well documented. Eoevania and Protoparevania
seem to be closer to the living lineages than earlier fossils.
Ensign wasp genera known only from fossils are:
Parasitic wasp
The term parasitoid wasp refers to a large evolutionary grade of hymenopteran superfamilies, mainly in the Apocrita. They are primarily parasitoids of other animals, mostly other arthropods...
s. It numbers around 20 extant genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
containing over 400 described species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, and is found all over the world except in the polar region
Polar region
Earth's polar regions are the areas of the globe surrounding the poles also known as frigid zones. The North Pole and South Pole being the centers, these regions are dominated by the polar ice caps, resting respectively on the Arctic Ocean and the continent of Antarctica...
s. The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of these solitary wasps feed on cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es and develop inside the egg-cases (ootheca
Ootheca
An ootheca is a type of egg mass made by any member of a variety of species .The word is a latinized combination of oo-, meaning "egg", from the Greek word ōon , and theca, meaning a "cover" or "container", from the Greek theke...
e) of their hosts.
Description
Evaniidae have the metasomaMetasoma
The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically...
attached very high above the hind coxae
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
on the propodeum
Propodeum
The propodeum is the first abdominal segment in Apocrita Hymenoptera . It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans...
, and the metasoma
Metasoma
The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically...
itself is quite small, with a long one-segmented tubelike petiole
Petiole (insect)
In entomology, the term petiole is most commonly used to refer to the constricted first metasomal segment of members of the Hymenopteran suborder Apocrita; it may be used to refer to other insects with similar body shapes, where the metasomal base is constricted...
, and compressed laterally over most of its length (segments 2-8). The ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
is short and thin. When active, these wasps jerk the metasoma up and down constantly, as referenced in their common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s. The mesosoma
Mesosoma
The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings....
is high, short and heavily sclerotized
Sclerosis (medicine)
In medicine, sclerosis refers to the stiffening of a structure, usually caused by a replacement of the normal organ-specific tissue with connective tissue.Types include:...
, with a ridged and pitted surfact. The head is largely immovable and attaches to the metasoma on a short neck, with usually 13-segment
Segment
Segment may mean:*The divisions found in the internal section of a citrus fruit* Market segment, the smaller subgroups comprising a marketComputing*Segmentation , the division of computer memory into segments...
ed antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
that do not differ between males and females.
Apomorphies of ensign wasp wings
Insect wing
Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...
and their venation are:
- deeply separated jugal lobes in fore- and hindwings
- loss of crossveins on the distal forewing (though this is hard to determine in some)
- hindwings retain only medial, cubital and part of the costal vein; all others have been lost
Ecology
As far as is known, ensign wasp larvae are predatory on the eggs of cockroachCockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
es. But good host data is only known for a fraction of this family, about 4% as of 2008, and thus it is likely that more unusual life history
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
strategies exist. Host specificity and coevolution with roach lineages seems to have played a significant factor in the evolution of some ensign wasp lineages. Others are less discriminating in their host choice and will attack almost any ootheca of a particular size.
The female wasp lays an egg inside the roach ootheca
Ootheca
An ootheca is a type of egg mass made by any member of a variety of species .The word is a latinized combination of oo-, meaning "egg", from the Greek word ōon , and theca, meaning a "cover" or "container", from the Greek theke...
(egg case), and the wasp larva hatches quickly and consumes the roach eggs. Technically, they are thus predators, rather than parasites or parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
s as other parasitic wasp
Parasitic wasp
The term parasitoid wasp refers to a large evolutionary grade of hymenopteran superfamilies, mainly in the Apocrita. They are primarily parasitoids of other animals, mostly other arthropods...
s. A single egg is laid per ootheca, into a host egg in some Evaniidae, and between the eggs in others. Some are able to oviposit even when the female cockroach still carries the fresh ootheca around, while other ensign wasps will only attack oothecae that are completed and have been dropped by the mother roach. The wasps seem to be able to determine if an ootheca is already used to host a larva, and refrain from depositing eggs in such cases; alternatively, the larvae might be cannibalic, with the first to hatch in an ootheca eating any wasp eggs subsequently deposited.
Two Evaniidae species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Evania appendigaster and Prosevania fuscipes, have achieved an essentially worldwide distribution nowadays, having been introduced along with various Blattidae
Blattidae
The Blattidae is a family of the order Blattaria . It contains several of the most common household cockroaches.-Selected species:*Oriental cockroach *American cockroach...
species of genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
Blatta
Blatta
Blatta is a genus of cockroach.- External Links :*...
and Periplaneta
Periplaneta
Periplaneta is a genus of cockroaches....
. While they do feed on insects that are considered pests, they rarely attain population size
Population size
In population genetics and population ecology, population size is the number of individual organisms in a population.The effective population size is defined as "the number of breeding individuals in an idealized population that would show the same amount of dispersion of allele frequencies under...
s sufficient to act as effective biocontrol
BioControl
BioControl is a peer-reviewed scientific journal published by Springer Science+Business Media covering all aspects of basic and applied research in biological control of invertebrate, vertebrate, and weed pests, and plant diseases. The journal was established in 1956 as Entomophaga and published by...
agents. As cockroaches are typically more abundant in and around human settlements, Evaniidae are a regular sight in such habitat where many other wasps are absent, and are frequently encountered in buildings looking for prey. The adults drink nectar from flowers and neither they nor the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e are dangerous or harmful to humans.
Systematics and taxonomy
Before 1939, the Evaniidae were a "wastebin taxonWastebin taxon
Wastebasket taxon is a term used in some taxonomic circles to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by their lack of one or more distinct character states or by their not belonging to one or more other taxa...
" for any parasitic wasp
Parasitic wasp
The term parasitoid wasp refers to a large evolutionary grade of hymenopteran superfamilies, mainly in the Apocrita. They are primarily parasitoids of other animals, mostly other arthropods...
with unusual morphology. Among these were the more apomorphic and less diverse (but about equally speciose) taxa now placed in the Aulacidae
Aulacidae
The family Aulacidae is a small cosmopolitan group, with 3 extant genera containing some 200 known species. They are primarily endoparasitoids of wood wasps and xylophagous beetles...
and Gasteruptiidae
Gasteruptiidae
The family Gasteruptiidae is one of the more distinctive among the Apocritan wasps, with surprisingly little variation in appearance for a group that contains around 500 species in 9 genera worldwide. The propleura form an elongated "neck", the petiole attaches very high on the propodeum, and the...
, which together with ensign wasps make up the superfamily
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Evanioidea. These were formerly a part of the paraphyletic "Parasitica", ranked as an infraorder. But the parasitic wasp lineages are not more closely related among themselves than they are related to unparasitic wasps, and thus the "Parasitica" are an obsolete group.
Rather, the Evanioidea seem to be close relatives of the Megalyroidea, Trigonaloidea, and particularly the Ceraphronoidea
Ceraphronoidea
Ceraphronoidea is a small Hymenopteran superfamily that includes only two families, and a total of some 800 species, though a great many species are still undescribed...
. These four superfamilies seem to make up a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
, which could be considered one of several infraorders to replace the superseded "Parasitica".
Living genera
The living ensign wasp generaGenera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
can be divided into one larger and four smaller groups, which might be considered subfamilies. Some genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
are hard to place in these though; they probably represent minor lineages of a more basal position. The groups, with genera sorted according to the presumed relationship, are:
Fossil record
Ensign wasps must have originated over 150 million years ago. Overall, they are successful organisms, existing since the time dinosaurs roamed the Earth with little change in morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and, presumably, ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
. The fossil record, in particular from fossil amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
, is quite comprehensive, with about 10 genera and twice as many species known from the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
right up to a few million years ago. The primitive Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
genera Andrenelia, Botsvania and Praevania are only tentatively identified as Evaniidae at present; the first was once separated as family Andreneliidae.
Evaniidae seem to have undergone significant evolutionary radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
in the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
; these taxa were separated as Cretevaniidae, but seem to be a subfamily if anything. The main lineages of extant ensign wasps probably were well separate by the mid-Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
. Few Evaniidae have been found in deposits dating from the Paleogene however, and the ancestry of the living genera consequently remains not well documented. Eoevania and Protoparevania
Protoparevania
Protoparevania is an extinct genus of Evaniidae from the Cretaceous.-References:* Paleo Bugs: Survival of the Creepiest by Timothy J. Bradley...
seem to be closer to the living lineages than earlier fossils.
Ensign wasp genera known only from fossils are:
- Eoevania Nel, Waller, Hodebert & De Ploeg, 2002
- ProtoparevaniaProtoparevaniaProtoparevania is an extinct genus of Evaniidae from the Cretaceous.-References:* Paleo Bugs: Survival of the Creepiest by Timothy J. Bradley...
Deans in Deans, Basibuyuk, Azar & Nel, 2004 - CretevaniaCretevaniaCretevania is an extinct genus of evaniid which existed in what is now China, England, Lebanon, Mongolia, Russia and Spain during the Cretaceous period. It was named by Rasnitsyn in 1975, and the type species is Cretevania minor.-Species:...
Rasnitsyn, 1975 (incl. Eovernevania & Procretevania) - Grimaldivania Basibuyuk, Fitton & Rasnitsyn in Basibuyuk, Rasnitsyn, Fitton & Quicke, 2000
- IberoevaniaIberoevaniaIberoevania is an extinct genus of evaniid which existed in what is now Spain during the early Cretaceous period. It was named by Enrique Peñalver, Jaime Ortega-Blanco, André Nel and Xavier Delclòs in 2010, and the type species is Iberoevania roblesi....
Peñalver et al., 20102010 in paleontology-Anomalocaridids:-Newly named crustaceans:-Newly named insects:* A new family, Cascopleciidae, is published by Poinar Jr.* A new family of ceraphronoid Hymenopters, Radiophronidae, is published by Ortega-Blanco, Rasnitsyn, and Delclòs.... - Newjersevania Basibuyuk, Quicke & Rasnitsyn in Basibuyuk, Rasnitsyn, Fitton & Quicke, 2000
- Andrenelia Rasnitsyn & Martinez-Delclos, 2000
- Mesevania Basibuyuk & Rasnytsin in Basibuyuk, Rasnitsyn, Fitton & Quicke, 2000
- Lebanevania Basibuyuk & Rasnitsyn in Basibuyuk, Rasnitsyn, Fitton & Quicke, 2002
- Praevania Rasnitsyn 1991
- Botsvania Rasnitsyn & Brothers, 2007
External links
- Evanioidea Online
- Evania appendigaster on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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