Diaeretiella rapae

Diaeretiella rapae (McIntosh)

Taxonomic placing: Insecta, Holometabola, Hymenoptera, Apocrita, Chalcidoidea,. Braconidae.

Geographical distribution: Cosmopolitan.

Morphology: Diaeretiella rapae is 2-3 mm in length, its size depending on the size of its host, being larger in larger hosts. The head and thorax are black, abdomen and legs yellowish brown

Life history: Diaeretiella rapae is a cosmopolitan solitary endoparasitoid of many aphids, and has several biotypes in different parts of the world. It usually attacks all stages of aphids that infest brassicas and cereal crops, the most prevalent host being Brevicoryne brassicae. Developmental time is usually around 2 weeks and fecundity comes to several hundred eggs/female, depending on the host and its size. Parasitized aphids are mummified, the parasite pupating therein and emerging as an adult. In the Middle East D. rapae is active mostly in the autumn through spring, rarely in summer. Among several aphid species assayed, Myzus persicae, due to its large body, was the most suitable host for mass-rearing D. rapae.

Economic importance: Diaeretiella rapae attacks about 100 aphid species infesting almost 200 plants in 43 plant families. Its main hosts, which it may control, are (besides B. brassicae) Diuraphis noxia, Myzus persicae, and Lipaphis erysimi. The parasitoid has been introduced into North America in order to control D. noxia infesting cereals. One method of releasing the parasitoid in a Brassicae plot is by placing cabbage plants that bear mummies in that plot.

Host plant effect: Cultivars of Brassica affected the percent parasitism of D. rapae on B. brassicae. Highest rates (40%) were on cabbage, as against 33% on turnips. Diaeretiella rapae, emerging from parasitized D. noxia that had infested resistant wheat cultivars were smaller, took longer to develop, and had fewer progeny, as compared with those from susceptible cultivars.

Effect of pesticides: Pyrethroids and a carbamate, when applied (against aphids), at slightly reduced rates, had only minimal adverse effects on parasitoid emergence from its hosts and on their subsequent survival, longevity and fecundity.

References

Brewer, M.J., Nelson, D.J., Ahern, R.G., Donahue, J.D. and Prokrym, D.R. 2001. Recovery and range expansion of parasitoids (Hymenoptera: Aphelinidae and Braconidae) released for biological control of Diuraphis noxia (Homoptera: Aphididae) in Wyoming. Environmental Entomology 30: 578-588.

El-Ghar, G.E.S. and El-Sayed, A. 1992. Long-term effects of insecticides on Diaeretiella rapae (M’intosh), a parasite of the cabbage aphid. Pest Management Science 36: 109-114.

Fukui, M., and Takada, H.. 1988. Fecundity, oviposition period and longevity of Diaeretiella rapae (M’Intosh) and Aphidius gifuensis Ashmead (Hymenoptera: Aphidiidae) two parasitoids of Myzus persicae (Sulzer) (Homoptera: Aphididae). Japanese Journal of Applied Entomology and Zoology 32: 331-333.

Hayakawa, D.L., Grafius, E. and Stehr, F.W. 1990. Effects of temperature on longevity, reproduction, and development of the asparagus aphid (Homoptera: Aphididae) and the parasitoid, Diaeretiella rapae (Hymenoptera: Braconidae). Environmental Entomology 19: 890-897.

Kant, R. and Minor, M.A. 2017. Parasitoid Diaeretiella rapae (Hymenoptera: Braconidae) adjusts reproductive strategy when competing for hosts. Environmental Entomology 46: 521-527.

Mescheloff, E. and Rosen, D. 1990. Biosystematic studies on the Aphidiidae of Israel (Hym.: Ichneumonoidea). 4. The genera Pauesia, Diaeretus, Aphidius, and Diaeretiella. Israel Journal of Entomology 24: 51-91.

Olmez Bayhan, S., Rifat Ulusoy, M. and Bayhan, E. 2007. Is the parasitization rate of Diaeretiella rapae influenced when Brevicoryne brassicae feeds on brassica plants? Phytoparasitica 35: 146-149.

Reed, D.K., Webster, J.A., Jones, B.G. and Burd, D.J. 1991. Tritrophic relationships of Russian wheat aphid (Homoptera: Aphididae), a hymenopterous parasitoid (Diaeretiella rapae McIntosh), and resistant and susceptible small grains. Biological Control 1: 35-41.

Silva, R.J., Cividanes, F.J., Pedroso, E.C. and Sala, S.R. 2011. Host quality of different aphid species for rearing Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae). Neotropical Entomology 40: 477-482.

Singh, R. and Singh, G. 2015. Systematics, distribution and host range of Diaeretiella rapae (Mcintosh) (Hymenoptera: Braconidae, Aphidiinae). International Journal of Research Studies in Biosciences 3: 1-36.

Zhang, W.Q. and Hassan, S.A. 2003. Use of the parasitoid Diaeretiella rapae (McIntoch) to control the cabbage aphid Brevicoryne brassicae (L.). Journal of Applied Entomology 127: 522–526.

Website

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