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Dicopomorpha echmepterygis

By Amber Fitzgerald and Elizabeth Wason

Geographic Range

The geographic range of the parasitoid Dicopomorpha echmepterygis spans across eastern North America (Mockford, 1997). Its range coincides with that of its host, Echmepteryx hageni (bark louse). (Mockford, 1997)

Habitat

As a parasitic wasp, Dicopomorpha echmepterygis spends the majority of its life cycle in the egg of its host, the bark louse. The bark louse lays its eggs in the bark of trees. (Mockford, 1997)

Physical Description

A great deal of sexual dimorphism exists in Dicopomorpha echmepterygis. The males are blind and wingless, with a body length of only 0.139 to 0.240 mm (Mockford, 1997). Dicopomorpha echmepterygis males are the smallest known adult insects (Gahlhoff, 1998). Male bodies, along with their relatively long legs, are a dull grayish brown. They have small heads that lack compound eyes, with unsegmented antennae (Mockford, 1997). The body volume of males is 1/8 that of the females (Grebennikov, 2008).

Dicopomorpha echmepterygis females have entirely black bodies with dusky brown legs and antennae. The antennae are twice as long as they are wide (Mockford, 1997). Unlike the diminutive males, females have slender wings that are slightly narrowed through the middle. The average forewing length is 0.447 mm, while the average hindwing length is 0.424 mm. Females have compound eyes that aid in dispersal from tree to tree (Gahlhoff, 1998). They also possess mandibles that project mesally and overlap at the tips, each with a pair of teeth (Mockford, 1997). The females are 40% larger than the males, measuring 0.386 to 0.550 mm long (Grebennikov, 2008). This significant sexual dimorphism is thought to result from the limited resources provided by host eggs (Gahlhoff, 1998). (Grebennikov, 2008; Mockford, 1997)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • sexes shaped differently
  • Range length
    0.139 to 0.550 mm
    0.01 to 0.02 in
  • Average wingspan
    0.894 mm
    0.04 in

Development

Nutrients within host eggs are limited; most nutrients contribute to the development of Dicopomorpha echmepterygis females (Mockford, 1997). The diminutive males require less nutrients to develop into adults (Gahlhoff, 1998). (Mockford, 1997)

Reproduction

Dicopomorpha echmepterygis primarily reproduces through brother-sister matings. Non-sibling matings may occur when males attach themselves to females, which subsequently disperse in search of new host eggs (Mockford, 1997). (Mockford, 1997)

Dicopomorpha echmepterygis females produce a single egg at a time, and eggs are about 0.106 to 0.110 mm long (Grebennikov, 2008). They lay their fluke-shaped eggs directly into the eggs of the host species, Echmepteryx hageni (Grebennikov, 2008). When parasitized, one host egg typically yields one female and one to three male parasitoids. The limited nutrients within the host egg are consumed primarily by the female wasp (Mockford, 1997). When mature, a female uses her mandibles to chew a hole through the egg (Mockford, 1997). Females breed once before they lay an egg and die. Males may never breed.

Sometimes a male uses his long legs to attach himself to the body of a female, thereby emerging from the host egg (Gahlhoff, 1998). The male then struggles toward the tip of the female’s abdomen and begins copulation. If the female already has copulated, she brushes away the male (Mockford, 1997). Sometimes a male clings to the female as she travels to new host eggs, where he may have non-sibling matings (Mockford, 1997).

Most males never leave the host egg, and they die there; however, females use their compound eyes and wings to disperse to other trees. By dispersing, females can find host eggs in which to deposit their own eggs (Gahlhoff, 1998). (Grebennikov, 2008; Mockford, 1997)

  • Breeding interval
    Females breed once before dying.

There is no observed parental care in this species.

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

The lifespan is very short, lasting from several hours to a few days (Boivin, 2010). (Boivin, 2010)

Behavior

The primary function of Dicopomorpha echmepterygis males is to mate with females. Females are vigorous and possess wings that aid in dispersal among trees in search of hosts (Gahlhoff, 1998). (Mockford, 1997)

Home Range

The male home range is limited to the host egg, unless he clings to a female that subsequently disperses (Mockford, 1997). Further research needs to be conducted to determine the range that a female will fly in search of a host. (Mockford, 1997)

Communication and Perception

Males are blind and wingless, with relatively large antennae. Their large antennae are believed to help them search for a mate (Mockford, 1997). Females have compound eyes and antennae. (Mockford, 1997)

Food Habits

For Dicopomorpha echmepterygis, the majority of the life cycle is spent within the host egg, where females consume the majority of the nutrients. The males require less nutrients and usually die before leaving the egg, while the female only lives long enough to chew her way out of the egg (using mandibles that project mesally and overlap at the tips, each with a pair of teeth), disperse, and lay her own eggs in other hosts (Mockford, 1997). (Mockford, 1997)

  • Animal Foods
  • eggs

Predation

Because Dicopomorpha echmepterygis spends most of its life within the host egg, it is largely protected from potential predators. It is unknown whether females have any predators when they disperse to lay eggs (Resh and Ring, 2003). (Resh and Ring, 2003)

Ecosystem Roles

Dicopomorpha echmepterygis is a species in the family Mymaridae, which contains other common parasitoid species that control crop pests (Mockford, 1997). (Mockford, 1997)

Species Used as Host

Economic Importance for Humans: Positive

Although other parasitoid species in the family Mymaridae may help control crop pests (Mockford, 1997), Dicopomorpha echmepterygis does not parasitize a pest insect. There is no known positive economic importance of D. echmepterygis. (Mockford, 1997)

Economic Importance for Humans: Negative

There is no known negative economic importance of Dicopomorpha echmepterygis.

Conservation Status

The conservation status of Dicopomorpha echmepterygis is not listed or has not yet been evaluated.

Other Comments

Dicopomorpha echmepterygis males are the smallest known adult insects. They are smaller than a single-celled paramecium (Gahlhoff, 1998). (Gahlhoff, 1998)

Contributors

Amber Fitzgerald (author), Radford University, Elizabeth Wason (author, editor), Animal Diversity Web Staff.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

References

Boivin, G. 2010. Phenotypic Plasticity and Fitness in Egg Parasitoids. Journal of Neotropical Entomology, 39/4: 457-463. Accessed November 08, 2011 at http://docs.google.com/viewer?a=v&q=cache:bRr9SJjNVn0J:www.scielo.br/pdf/ne/v39n4/01.pdf+Dicopomorpha+echmepterygis+Mockford,+1997&hl=en&gl=us&pid=bl&srcid=ADGEESgXjc10lShwA7AB7jw6Ii97QRsju-YlTer9Hdr-JlI_4oNvljxfrZS1i_f-UYiPR9h85wGYkS46Hej1WyH61WH8llhl3fcYpz0vdwTA2kr5PMLB-wXM7b_vtmoxyQ2H5QZEf2v0&sig=AHIEtbTjtp31dvAm-rzFDWe4sEclBWq2lg.

Gahlhoff, J. 1998. Smallest Adult. Pp. Chapter 38 in T Walker, ed. University of Florida Book of Insect Records. University of Florida: Department of Entomology & Nematology. Accessed November 12, 2011 at http://entnemdept.ufl.edu/walker/ufbir/files/pdf/UFBIR_Chapter38.pdf.

Grebennikov, V. 2008. How Small You Can Go: Factors Limiting Body Miniaturization in Winged Insects. European Journal of Entomology, 105: 313-328. Accessed November 12, 2011 at http://www.eje.cz/pdfarticles/1333/eje_105.

Mockford, E. 1997. A New Species of Dicopomorpha (Hymenoptera: Mymaridae) with Diminutive, Apterous Males. Annals of the Entomological Society of America, 90: 115-120.

Noyes, J. 2011. "Universal Chalcidoidea Database" (On-line). Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist. Accessed November 14, 2011 at http://data.gbif.org/datasets/resource/1576.

Resh, V., C. Ring. 2003. Encyclopedia of Insects. Amsterdam: Amsterdam Academic.

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