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Psolodesmus mandarinus mandarinus with female of Hydrophylita emporos - journal.pone.0069331.g005.png
A female Hydrophylita emporos on a female Psolodesmus mandarinus mandarinus.
Scientific classification

ca. 80 genera

Megaphragma mymaripenne

The Trichogrammatidae are a family of tiny wasps in the Chalcidoidea that include some of the smallest of all insects, with most species having adults less than 1 mm in length. The over 840 species are placed in about 80 genera; their distribution is worldwide. Trichogrammatids parasitize the eggs of many different orders of insects. As such, they are among the more important biological control agents known, attacking many pest insects (especially Lepidoptera).

They are not strong fliers and are generally moved through the air by the prevailing winds. Their fore wings are typically somewhat stubby and paddle-shaped, with a long fringe of hinged setae around the outer margin to increase the surface area during the downstroke. Males of some species are wingless, and mate with their sisters inside the host egg in which they are born, dying without ever leaving the host egg.

Trichogrammatidae have unique nervous systems resulting from the necessity to conserve space. They have one of the smallest nervous systems, with one particularly diminutive species, Megaphragma mymaripenne, containing as few as 7,400 neurons. They are also the first (and only) known animals which have functioning neurons without nuclei.[1][2]

The neurons develop during pupation with functional nuclei and manufacture enough proteins to last through the short lifespans of the adults. Before emerging as an adult, the nuclei are destroyed, allowing the wasp to conserve space by making the neurons smaller. Even without nuclei (which contain the DNA, essential for manufacturing proteins to repair damage in living cells), the neurons can survive because the proteins manufactured as a pupa are sufficient.[2]



  1. ^ Polilov, A. A. (2012). "The smallest insects evolve anucleate neurons". Arthropod Structure & Development. 41 (1): 29–34. doi:10.1016/j.asd.2011.09.001. PMID 22078364.
  2. ^ a b Bob Yirka (December 1, 2011). "Entomologists discover first instance of intact neurons without nucleus - in fairy wasps". Retrieved December 2, 2011.
  • Doutt, R.L. & Viggiani, G. 1968. The classification of the Trichogrammatidae (Hymenoptera: Chalcidoidea). Proceedings Calif. Acad. Sci. 35:477-586.
  • Matheson, R. & Crosby, C.R. 1912. Aquatic Hymenoptera in America. Annals of the Entomological Society of America 5:65-71.
  • Nagarkatti, S. & Nagaraja, H. 1977. Biosystematics of Trichogramma and Trichogrammatoidea species. Annual Review of Entomology 22:157-176.

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