Psyttalia concolor (Szépligeti)
(Formerly known as Opius concolor (Szépligeti))
Systematic position: Insecta, Holometabola, Hymenoptera, Apocrita, Chalcidoidea, Braconidae.
Morphology: The adults are about 3.5 mm in length, with orange colored bodies, black eyes and long antennae.
Distribution: Of Mediterranean origin, P. concolor has been distributed through much of the world for the biological control of pest tephritids (fruit flies).
Life history: Psyttalia concolor inserts an egg into the tephritid larva (maggot), which resides inside its host fruit, without killing the larva. The tephritid continues to feed until it pupates, when the parasitoid egg hatches, feeds on the tephritid and kills it, thus being a larval-pupal parasite (a koinobiont). The parasitoid usually attacks third instar host larvae, but in the laboratory may also parasitize younger instars. Rates of parasitism on the olive fly, Bactrocera oleae, were higher on smaller fruits than in the larger fruits, probably due to the parasitoid’s short ovipositor which may not reach the host in the latter fruits. Fecundity is about 20-30 eggs/female. Host larvae superparasitized with two eggs were best for parasitoid development, whereas 4 eggs or more killed the host. Irradiation of the host flies had no effect on the parasitoids developing within. The calculated threshold of development is at about 12°C, and 250 day degrees are needed to complete a generation. At 15°C and 65% RH adult parasitoids survived for 2 days without food as compared to 48 days when provided with honey. Strains of P. concolor from different regions (sometimes termed “African” and “Sicilian”) may differ in size, longevity and fecundity.
Economic importance: Psyttalia concolor is an important natural enemy of several major tephritid pests, especially Ceratitis capitate and Bactrocera oleae. It was introduced into various regions to control these pests. Inoculative releases (of 20–30 parasitoids/tree) reduced B. oleae infestations in Sicily by about 80%, in Egypt by about 40-50%. No deleterious effects were seen when a transgenic strain of B. oleae served as hosts for P. concolor.
Effect of Pesticides (applied against the pests): Spinosad was very harmful to P. concolor, neem caused a reduction in parasitoid progeny size, whereas the insect growth regulator Tebufenozide was harmless.
References
Abdel-Magid, J.E. and Hammad, K.A. 2000: Seasonal abundance of Bactrocera (Dacus) oleae Gmelin and its parasitoid, Opius concolor (Hymenoptera: Braconidae) in El-Khattara district, Sharkia Governorate, Egypt. Zagazig Journal of Agricultural Research (Egypt). 26: 163-175.
Argov, Y. and Gazit Y. 2008. Biological control of the Mediterranean fruit fly in Israel: introduction and establishment of natural enemies. Biological Control 46: 502-507.
Canale, A. and Benelli, G. 2012. Impact of mass-rearing on the host seeking behaviour and parasitism by the fruit fly parasitoid Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae). Journal of Pest Science 85: 65–74.
Delrio , G., Lentini , A. and Satta, A. 2005. Biological control of olive fruit fly through inoculative eeleases of Opius concolor Szepl. IOBC/WPRS Bulletin 30(9): 53–58.
Hepdurgun, B., Turanli, T. and Zümreoğlu, A. 2009. Parasitism rate and sex ratio of Psyttalia (=Opius) concolor (Hymenoptera: Braconidae) reared on irradiated Ceratitis capitata larvae (Diptera: Tephritidae). Biocontrol Science and Technology, Supplement 1, 19: 157-165.
Kimani-Njogu, S.W., Trostle, M.K., Wharton, R.A., Woolley, J.B. and Raspi, A. 2001. Biosystematics of the Psyttalia concolor species complex (Hymenoptera: Braconidae: Opinae): The identity of populations attacking Ceratitis capitata (Diptera: Tephritidae) in Coffee in Kenya. Biological Control 20: 167–174.
Loni, A. 1997. Developmental rate of Opius concolor (HYM.: Braconidae) at various constant temperatures. Entomophaga 42: 359–366.
Loni, A. 2003. Impact of host exposure time on mass-rearing of Psyttalia concolor (Hymenoptera Braconidae) on Ceratitis capitata (Diptera Tephritidae) Bulletin of Insectology 56: 277-282.
Marubbi, T. (and 7 co-authors) 2017. Exposure to genetically engineered olive fly (Bactrocera oleae) has no negative impact on three non-target organisms. Scientific Report 7: 11478.
Mustafa, T.M. and Al-Zaghal, K. 1987. Frequency of Dacus oleae (Gmelin) immature stages and their parasites in seven olive varieties in Jordan. Insect Science and its Application 8: 165-169.
Omar, A.H., El-Sherif, H. Khawas, M.A. and El-Heneidy, A.H. 2001. Survey and seasonal abundance of the parasitoids of the olive fruit fly, Bacterocera (Dacus) oleae Gmel. (Diptera: Tephretidae) in Egypt. Arab Journal of Plant Protection 19: 80-85 (in Arabic with an English abstract).
Sime, K.R., Daane, K.M., Messing, R.H. and Johnson, M.W. 2006. Comparison of two laboratory cultures of Psyttalia concolor (Hymenoptera: Braconidae), as a parasitoid of the olive fruit fly. Biological Control 39: 248-255.
Viñuela, E. (and 6 co-authors) 2001. Comparison of side-effects of spinosad, tebufenozide and azadirachtin on the predators Chrysoperla carnea and Podisus maculiventris and the parasitoids Opius concolor and Hyposoter didymator under laboratory conditions. IOBC/wprs Bulletin 24: 25-34.
Wang, X.-G. Johnson, M.W., Daane, K.M. and Yokoyama, V.Y. 2009. Larger olive fruit size reduces the efficiency of Psyttalia concolor as a parasitoid of the olive fruit fly. Biological Control 49: 45-51.
Yokoyama, V.Y., Rendon, P.A. and Sivinski, J. 2008. Psytalia cf. concolor (Hymenoptera: Braconidae) for biological control of olive fruit fly (Diptera: Tephritidae) in California. Environmental Entomology 37: 764–773.