Russian wheat aphid in Konya province

Summary

To determine the present situation of Diuraphis noxia (Kurdjumov) in Konya province, five localities were surveyed at 7-10 day intervals during the 1989–1990 growing season. Population development, alternate hosts, and natural enemies of this species were observed. While D. noxia was found in small numbers in the autumn of 1989, its population suddenly increased to epidemic levels in 1990. This dramatic increase occurred at the end of wheat heading. The injury level of D. noxia in Turkey is relatively low. This is probably more related to the unsuitable conditions of wheat growth stages during which the pest population is increasing, rather than to the effects of its rich, natural enemy complex. After wheat harvest, the aphid moved to Hordeum murinum L. ssp. glaucum (Steudel) Tzvelev, Phalaris spp. and volunteer wheat and barley plants. The D. noxia population on late sown wheat was three times higher than that on early sown plants. Conversely, the numbers of parasitised aphids and predator mites were higher in early sown wheat. Varieties Kunduru 1149 and Atay 85 were found to be more susceptible, while Kiraç 66, Bolal 2973 and Gerek 79, early maturing and drought tolerant varieties, were determined as relatively more resistant. A low level of antibiosis was also observed only on Bolal 2973 by laboratory tests. Threshold for development and thermal constant of D. noxia were 6.1 °C and 94.5 daydegrees, respectively. Theoretical generation number of this aphid in the Central locality of Konya province was 22.3 for 1990.