Diachasmimorpha longicaudata

Diachasmimorpha longicaudata is a solitary species of parasitoid wasp and an endoparasitoid of tephritid fruit fly larvae. D. longicaudata is native to many countries in Southeast Asia and subtropical regions and has also been introduced to many other countries as a biological control agent. It is now considered the most extensively used parasitoid for biocontrol of fruit flies in both the southern portion of the United States and Latin America.[1] D. longicaudata is especially useful for agricultural purposes in the control of fruit flies as it is easily mass-reared and has the ability to infect a variety of hosts within the genus Bactrocera.[2] A negative factor in its use as a biocontrol agent is that it is known to oviposit in grapefruit in the state of Florida. This has resulted in quarantines on grapefruit shipped internationally as well as domestically.[3] Research is ongoing to determine whether D. longicaudata is actually a single species, or if it contains multiple species. It is likely multiple biological species separated by both reproductive isolation and morphological characteristics such as wing geometry.[4]

Diachasma longicaudata
Female D. longicaudata
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Braconidae
Subfamily:	Opiinae
Genus:	Diachasmimorpha
Species:	D. longicaudata

Distribution

Diachasmimorpha longicaudata originated in the Indo-pacific region of Asia.[2] D. longicaudata has been disseminated into countries in the Americas including United States, Colombia, Costa Rica, Guatemala, El Salvador, Nicaragua, and Trinidad, and Brazil.[1] There are stable colonies in Hawaii and Florida in the United States.

Morphology

The genus Diachasmimorpha has traditionally been defined by the morphology of their apically sinuate ovipositor.[5] D. longicaudata has a body length of between 2.8 and 5.4 mm. The adult male is smaller than the female with a body length of up to 4.0 mm. The body is a reddish-brown color and antennae are longer than the body. Wings are clear. Females have a long ovipositor. The gaster of males and females differs slightly with the female having a dorsal central black band while the gaster of the male has a dark brown to black dorsal posterior.[6]

Three cryptic species have been identified within D. longicaudata based on genetic analysis and geometric differences in wing venation.[4] In forced-contact mating between the three cryptic species reproduction was rare and resulted in sterile female offspring. Subspecies have also been reported based on differing geographical areas with high variation being associated variation of resources.[4] As many as five subspecies have previously been identified around the world and have been primarily characterized by color.[2]

Life cycle

The host organism of Diachasmimorpha longicaudata. Tephritid fruit flies. Pictured is Tephritis formosa.

Both males and females are solitary. Third instar tephritid fruit fly larvae are the typical hosts.[7] Female adults of D. longicaudata are attracted to fermenting fruit and then are able to find larvae by sound. Females lay 13-24 eggs per day using her elongated ovipositor to reach the fly larvae. Typically only one egg is laid per instar larvae with exceptions when hosts are insufficient; however only one pupa will reach maturity.[7] Eggs take between two and five days to hatch and will take 18–23 days to reach adulthood.[6] Male parasitoids develop faster than female, emerging two to three days before females from their host.[7]

Symbiotic virus

Diachasmimorpha longicaudata entomopoxvirus (DlEPV) is a notable symbiotic virus that affects Diachasmimorpha longicaudata. DlEPV has a double-stranded DNA genome of 250–300 kb A-T rich with more than 60 of the genome being A-T.[8]

During oviposition, the parasitic wasp infects tephritid fruit fly with DlEPV as well as rhabdovirus (DlRhV). Both DlEPV and DlRhV replicate within the epidermal cells of their new host. These viruses are found within the adult wasps and retained in subsequent generations.[9] This is the first symbiotic EPV described to date from a parasitic wasp.[8]

References

1. Schliserman, Pablo; Ovruski, Sergio M.; De Coll, Olga R. (2003-12-01). "The establishment of diachasmimorpha longicaudata (hymenoptera: braconidae) in misiones, northeastern argentina". Florida Entomologist. 86 (4): 491–492. doi:10.1653/0015-4040(2003)086[0491:TEODLH]2.0.CO;2. ISSN 0015-4040.
2. Kitthawee, Sangvorn; Dujardin, Jean-Pierre (2016-09-01). "The Diachasmimorpha longicaudata complex in Thailand discriminated by its wing venation". Zoomorphology. 135 (3): 323–332. doi:10.1007/s00435-016-0307-x. ISSN 0720-213X.
3. Ashley, T. R.; Chambers, D. L. (1979-12-01). "Effects of parasite density and host availability on progeny production byBiosteres (Opius) longicaudatus, [Hym.: Braconidae], a parasite ofAnastrepha suspensa [Dip.: Tephritidae]". Entomophaga. 24 (4): 363–369. doi:10.1007/BF02374175. ISSN 0013-8959.
4. Kitthawee, Sangvorn; Dujardin, Jean-Pierre (2009-10-01). "The Diachasmimorpha longicaudata complex: Reproductive isolation and geometric patterns of the wing". Biological Control. 51 (1): 191–197. doi:10.1016/j.biocontrol.2009.06.011.
5. "Changes in nomenclature and classification of some opiine Braconidae (Hymenoptera)". Proceedings of the Entomological Society of Washington. 89 (1). 1987. ISSN 0013-8797.
6. "a parasitoid wasp - Diachasmimorpha longicaudata (Ashmead)". entnemdept.ufl.edu. Retrieved 2017-11-16.
7. Paladino, Leonela Zusel Carabajal; Papeschi, Alba Graciela; Cladera, Jorge Luis (2010-01-01). "Immature Stages of Development in the Parasitoid Wasp,Diachasmimorpha longicaudata". Journal of Insect Science. 10 (56): 56. doi:10.1673/031.010.5601. PMC 3014816. PMID 20569133.
8. Mwaengo, D. M.; Lawrence, P. O. (2003-06-01). "A putative DNA helicase and novel oligoribonuclease in the Diachasmimorpha longicaudata entomopoxvirus (DlEPV)". Archives of Virology. 148 (7): 1431–1444. doi:10.1007/s00705-002-0975-3. ISSN 0304-8608. PMID 12827471.
9. Lawrence, Pauline O.; Matos, Luis F. (2005-02-01). "Transmission of the Diachasmimorpha longicaudata rhabdovirus (DlRhV) to wasp offspring: an ultrastructural analysis". Journal of Insect Physiology. Non-poly-DNA viruses, their parasitic wasps and hosts. 51 (2): 235–241. doi:10.1016/j.jinsphys.2005.01.002. PMID 15749107.