OENOTHERA BIENNIS L.: AN INVASIVE ALIEN PLANT SPECIES AS A RESERVOIR OF APHIDOPHAGOUS INSECTS IN AGROECOSYSTEMS

OENOTHERA BIENNIS L.: AN INVASIVE ALIEN PLANT SPECIES AS A RESERVOIR OF APHIDOPHAGOUS INSECTS IN AGROECOSYSTEMS. Snezana Tomanevic', Z. Tomanovlc-, S. Jovanovic', P. Boza" and N.G. Kavallieratos", IMilitary Medical Academy, Cmotravska 17, 11000 Belgrade, Serbia and Montenegro; /Institute ofZoology, Faculty ofBiology, University ofBelgrade, 11 000 Belgrade, Serbia and Montenegro; 'Institute ofBotany and Botanical Garden, Faculty of Biology, University of Belgrade, 11000 Belgrade, Serbia and Montenegro; "Department ofBiology and Ecology, University ofNovi Sad, 21000 Novi Sad, Serbia and Montenegro; 5Benaki Phytopathological Institute, Department ofEntomology and Agricultural Zoology, Laboratory ofAgricultural Entomology, 8 Stefanou Delta, 14561 Kifissia, Attica, Greece

It was thought that the genus Oenothera is of North American origin, but there are opinions to the effect that some species found in Europe were established by hybridization of alien Oenothera species introduced from North America 'and consequently have European origin (Jalas and Suominen, 1980;BoZa and Kn ez e v i c , 1988).In Europe, Oenothera biennis was introduced at the beginning ofthe XVITth centuryinto Italy, from which it spread all over the continent (D ikl i c , 1973).There also those who hold that D. biennis is of European origin ,306, 1966).Reported for the first time by Pan c i c (1874) in Serbia and Vojvodina by Zork6czy ( 1896), it is one of the most invasive plants in Central Europe.Oenothera biennis grows mainly on sandy soil or clay.It occurs sub spontaneously and grows by roads and railroads; on embankments, sandy terrains and river banks; and in fields, dry meadows, gardens, hedges, and nurseries (Zlatkovi6 et al.,1998).
Aphis oenotherae Oestlund (Fig. I) is a North American species that probably was introduced in Europe by aeroplane (Muller, 1974).The first report of A. oenotherae in Europe dates back to 1971 (Hille Ris La m b e r s , 1971), although Moesz (1938) allegedly reported aphids on D. biennis in Hungary (unchecked data).This aphid species lives on flower buds, stem, and leaves of Oenothera plants, causing plant deformations (Heie, 1986).
In the Belgrade area during the period of 2000-2003, we collected samples of Oenothera biennis bearing colonies of Aphis oenotherae consisting of both live and mummified aphids.These samples were reared for several weeks in the laboratory until parasitoids and predators emerged.
We reared three species of primary and one species of secondary parasitoid adapted to parasitize new immigrant aphids.Lysiphlebus [abarum (Marsh.) is a primary parasitoid which belongs to the family Aphidiidae (Hymenoptera).It is a polyphagous species which prefers steppe habitats (S t ar y , 1963; To m a n o v i c and Br aj k o vi c , 2001).The association Oenothera biennislAphis oenotherael Lysiphlebus fabarum was reported for the first time from the Palaearctic (Tomanovi6 et al., 2003).Aphelinus varipes (Foerster) and Aphelinus chaonia 13P (Walker) are also primary parasiroids of aphids, but ones which belong to the family Aphelinidae (Hymenoptera).Both species are of pa1aearctic origin.The association Denathera biennisl Aphis oenotheraelAphelinus varipes and that of the first two species with A. chaonia are new for the Palaearctic.Aphelinus varipes is a very important agent for biocontrol of Russian wheat aphids, Diuraphis noxia (Kurdj.) (Hopper et ai., 1995).
This species was introduced in the USA for Control of D. noxia (Burd et al., 2001).Aphelinus chaonia also represents an important agent for biocontrol of grain aphids (Krotova, 1993).The only secondary parasitoid is Syrphophagus aphidivorus (Mayr) (Encyrtidae, Hymenoptera), which is a common species in agroecosystems (Tomanov i c and Braj kovi 6,2001).
S ta r y (1970) classified foci in ecosystems and the role of separate plant species as reservoirs of beneficial parasitoid species in agroecosystems.Oenothera biennis represents a reservoir of beneficial parasitoid species that can migrate to agroecosysterns and parasitize pest aphid species there.The above-mentioned three predatory species establish relations with pest aphid species in agroecosystems.Aphis oenotherae is monophagous aphid normally restricted to Oenothera plants, but it and has become well adapted to the new environment of agroecosystems.Its natural enemies are oligophagous or polYPhagous species in the agroecosystems.