''Evania appendigaster'', also known as the blue-eyed ensign wasp, is a species of

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

in the family Evaniidae. Its native range is not known, but it likely originated in

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

. Today it occurs throughout the

tropics The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

subtropics The subtropical zones or subtropics are geographical and climate zones immediately to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately ...

and in many

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

regions. As with the rest of its family, the blue-eyed ensign wasp is a

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

known for specializing on

cockroach Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...

eggs.Strange, L. A
A Cockroach Egg Parasitoid, ''Evania appendigaster'' (Linnaeus) (Hymenoptera: Evaniidae).
EENY-162 (IN319). Entomology and Nematology. Florida Cooperative Extension Service. University of Florida IFAS. 2000.

Description

This is one of the larger ensign wasps, with forewings up to about 7 millimeters long. It is distinguished from other species by the wide separation of the first and second sections of the coxa, the segment of the

leg A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...

that attaches to the body. Its body is black in color with contrasting blue eyes. The abdominal petiole, the constricted stalk that holds the posterior section of the abdomen, or gaster, is attached high on the body. The gaster is laterally compressed and oval to nearly triangular in shape, held in a flaglike fashion and resembling an

ensign Ensign most often refers to: * Ensign (flag), a flag flown on a vessel to indicate nationality * Ensign (rank), a navy (and former army) officer rank Ensign or The Ensign may also refer to: Places * Ensign, Alberta, Alberta, Canada * Ensign, Ka ...

, a characteristic of the family that inspired the common name ensign wasp.

Biology

This wasp reproduces by laying eggs into egg cases, or oothecae, of cockroaches. The wasp

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e use the cockroach eggs as a food source. Host cockroaches include the American cockroach (''Periplaneta americana''), Australian cockroach (''P. australasiae''), brown cockroach (''P. brunnea''), Oriental cockroach (''Blatta orientalis''), whitemargined cockroach (''Melanozosteria soror''), and harlequin cockroach (''Neostylopyga rhombifolia''). The complete life cycle of the species is summarized on a video available online. Detailed descriptions of the

oviposition The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...

process in this species have been published. As one 1920 account describes it, "the Evaniid left the inside wall of the confining tumbler, ran over the Blattid ootheca, crawled over the surface momentarily as she actively vibrated her antenna and finally settled upon it with the long axis of her body parallel with the long axis of the egg mass as it lay upon its right side. Having satisfactorily settled herself, lying upon her right side she extended her ovipositor and crawling slightly forward she punctured the ootheca in the fifth egg cell of the left side, remaining in position for about fifteen minutes. She then left the egg mass and resting upon the inside wall of the tumbler actively cleaned the ovipositor, wings and antennae." As a 1957 account describes the "peculiar" egg-laying behavior, "the female lies on her side and, with legs braced against the oötheca, penetrates the tough integument of the egg-capsule after about half-an-hour's hard labour." The process apparently requires "a good deal of hard work and much wriggling of the abdomen." Other authors describe it as a seven-step process. The wasp lands on the ootheca and drums on it with her antennae. During step two, she extends her ovipositor and taps on the ootheca in several places for up to ten minutes, apparently searching for an appropriate site. After a rest period she begins "drilling", repeatedly inserting her ovipositor. Step five is the actual oviposition stage, in which wasps "just sit on ootheca and lay eggs". Steps six and seven are the withdrawal of the ovipositor and departure, respectively. One egg is deposited in each cockroach egg capsule, and the wasp larva consumes all the eggs within it. The larva proceeds through five

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

s during development, stages which are distinguished by the changes in the unique mandibles. The first instar has mandibles with small, sharp teeth which it must use to open the tough cockroach eggs. During the next two instars, the larva has longer mandibles which are "shaped like a gauntlet glove" with three teeth. The final two instars have thicker mandibles with a long, blunt upper tooth and a narrow, curving lower tooth. When the larva reaches about 8 millimeters in length it

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

tes. Upon maturity it cuts a hole in the egg capsule and exits. The adult wasp lives for two or three weeks. It may spend some time on plants such as

parsley Parsley, or garden parsley (''Petroselinum crispum''), is a species of flowering plant in the family Apiaceae that is native to Greece, Morocco and the former Yugoslavia. It has been introduced and naturalisation (biology), naturalized in Eur ...

and

fennel Fennel (''Foeniculum vulgare'') is a flowering plant species in the carrot family. It is a hardy, perennial herb with yellow flowers and feathery leaves. It is indigenous to the shores of the Mediterranean but has become widely naturalized ...

Competitors Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indi ...

include '' Aprostocetus hagenowii'', another parasitoid wasp that attacks cockroach oothecae.

Research

The larvae of the species have been described in minute details. The complete

mitochondrial A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

of this species has been sequenced. The wasp may be a candidate for use as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

of cockroaches. Control might be even better if the wasp were released along with ''A. hagenowii'', which tends to have a higher rate of parasitism. The wasp can be bred in laboratory conditions for later release. The parasitizing capacity depends on the density of host oothecae. The development and parasitisation rates are temperature-dependent.

References

# Strange, L
A Parazitoid ouă de gândac, ''Evania appendigaster'' (Linnaeus) (Hymenoptera: Evaniidae)
EENY-162 (IN319). Entomologie și Nematologie. Serviciul de extindere cooperativă din Florida. Universitatea din Florida IFAS. 2000. # Yeh, Chin-Chang; Chi-Chang Huang; Cheng-Shing Lin (2000)
„Experiența anterioară afectează comportamentul ovipoziției la Evania appendigaster (L.) (Hymenoptera: Evaniidae)”
(PDF) . Jurnalul Chinez de Entomologie . 20 : 13–21 . # Fox, Eduardo (10 mai 2011)
„Evania appendigaster”
. YouTube . # Haber, Vernon R. (1920)
„Ovipoziție de către un evaniid, Evania appendigaster Linn”
. Entomologul canadian . 52 (11): 248. doi : 10.4039/Ent52248-11 . # Cameron, Ewen (1957)
"Despre paraziții și prădătorii gândacului. II.— Evania appendigaster (L.)"
. Buletin de Cercetări Entomologice . 48 (1): 199– 209. doi : 10.1017/S0007485300054171 . # Fox, Eduardo Gonçalves Paterson; Solis, Daniel Russ; Rossi, Mônica Lanzoni; Eizemberg, Roberto; Taveira, Luiz Pilize; Bressan-Nascimento, Suzete (iunie 2012). „Stadiile preimaginale ale viespei ensign Evania appendigaster (Hymenoptera, Evaniidae), un prădător de ouă de gândaci” . Biologia nevertebratelor . 131 (2): 133– 143. doi : 10.1111/j.1744-7410.2012.00261.x . # Wei, Shu-jun; Tang, Pu; Zheng, Li-hua; Shi, Min; Chen, Xue-xin (2010)
„Genomul mitocondrial complet al Evania appendigaster (Hymenoptera: Evaniidae) are un conținut scăzut de A+T și un distanțier intergenic lung între atp8 și atp6 ”
. Rapoarte de biologie moleculară . 37 (4): 1931– 1942. doi : 10.1007/s11033-009-9640-1 . PMC 2831182 . PMID 19655273 . # Hwang, Shaw-Yhi; Chen, Ling-Mei (1 octombrie 2004). „Efectele a patru tratamente fizice ale oothecae de Periplaneta americana asupra parazitismului și dezvoltării viespei parazitare Evania appendigaster ” . Entomologia mediului . 33 (5): 1321– 1326. doi : 10.1603/0046-225X-33.5.1321 . # Bressan-Nascimento, S.; Oliveira, DMP; Fox, EGP (decembrie 2008). „Cerințe termice pentru dezvoltarea embrionară a Periplaneta americana (L.) (Dictyoptera: Blattidae) cu potențială aplicare în creșterea în masă a parazitoizilor ouă”. Control biologic . 47 (3): 268– 272. doi.org/10.1016%2Fj.biocontrol.2008.09.001 . # Fox, EGP; Bressan-Nascimento, Suzete (februarie 2006). „Caracteristicile biologice ale Evania appendigaster (L.) (Hymenoptera: Evaniidae) în diferite densități ale Periplaneta americana (L.) oothecae (Blattodea: Blattidae)”. Control biologic . 36 (2): 183– 188. doi.org/10.1016%2Fj.biocontrol.2005.09.006 . # Bressan-Nascimento, S.; Fox, EGP; Pilizi, LGT (februarie 2010). „Efectele diferitelor temperaturi asupra istoriei vieții Evania appendigaster L. (Hymenoptera: Evaniidae), un parazitoid otecal solitar al Periplaneta americana L. (Dictyoptera: Blattidae)”. Control biologic . 52 (2): 104– 109. doi.org/10.1016%2Fj.biocontrol.2009.10.005 . {{Taxonbar, from=Q2171907 Evanioidea Hymenoptera of Africa Hymenoptera of Asia Hymenoptera of Australia Hymenoptera of Europe Hymenoptera of North America Hymenoptera of South America Wasps described in 1758 Taxa named by Carl Linnaeus