Trioxys pallidus

Trioxys pallidus (Haliday)

Systemtic position: Insecta, Holometabola, Hymenoptera, Apocrita, Chalcidoidea, Braconidae.

Morphology: Head, antennae and thorax black, abdomen mostly dark with yellow stripes, about 1.5-3.0 mm in length.

Life history: A solitary endoparasitoid of aphids. The female lays an egg inside the host nymphs, usually preferring the elder stages. The emerging larva consumes the inside of the host, develops therein and pupates within the mummified aphid. The adult emerges through a small exit hole.

Economic importance: A major natural enemy of Monellia caryella and _Chromaphis juglandicola. Occurring naturally in the Middle East, it suppresses pest aphids attacking walnut in Turkey and has successfully been introduced into California. Overall its parasitism rates may reach 50-95%.

Effect of pesticides: Applications of insecticides can reduce the controlling effect of T. pallidus. Hyperparasitism early in the season can also diminish the effect of T. pallidus.


Atlihan, R., ÖzgÖkÇe , M.S., AkkÖprÜ E.P., Kasap, I., Kaydan, M.B. and Senal, D. 2015. Seasonal abundance of aphids and their natural enemies in walnut orchards in Lake Van Basin, Turkey. Türkiye Biyolojik Mücadele Dergisi 6: 3-12.

Hougardy, E. and Mills, N.J. 2009. Factors influencing the abundance of Trioxys pallidus, a successful introduced biological control agent of walnut aphid in California. Biological Control 48: 22-29.

Mansour, F. 1988. Parasites of Monellia caryella [Hom.: Aphididae]: Phenology and effect on the aphid population in pecan orchards in Israel. Entomophaga 33: 371–375

Mescheloff, E. and Rosen, D. 1993. Biosystematic studies on the Aphidiidae of Israel (Hymenoptera: Ichneumonoidea). 5. The genera Trioxys and Binodoxys. Israel Journal of Entomology 27: 31-47.

Rakhshani, E., Talebi, A.A., Kavallieratos, N. and Fathipour1, Y. 2004. Host stage preference, juvenile mortality and functional response of Trioxys pallidus (Hymenoptera: Braconidae, Aphidiinae). Biologia, Bratislava 59: 197-203.

van den Bosch, R., Hom, R., Matteson, P., Frazer, B.D., Messenger, P.S. and Davis, C.S. 1979. Biological control of the walnut aphid in California: impact of the parasite Trioxys pallidus. Hilgardia 47: 1-13.