Biological Responses of Russian Wheat Aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae) to Different Wheat Varieties

In recent years, the Russian Wheat Aphid, has been included worldwidely in the list of
the important pests of cereals, particularly wheat plants. In addition to direct serious
damage, the aphid is the main vector of Barley Yellow Dwarf, Barley Mosaic, and Sugarcane
Mosaic Viruses. The pest was reported from East Azarbaidjan province (Iran) a few
years ago and it is now widespread in Tabriz, Ahar and Kaleybar wheat fields. In the present
study, the possibility of any resistance was looked for at the tillering stage in Sardari,
Sabalan, Alvand, Zarrin and Alamoot, the most extensively planted varieties in the province.
The experiment was conducted under glasshouse conditions of 24.4±1.6 oC with 50-
60% R.H. and a photoperiod of 14:l0(L:D). Antibiosis was determined by studying the
percentage survival of the nymphs, their developmental time, and fecundity (total number
of progeny per /female produced within the first 10 and 15 days of the reproductive cycle)
calculating the relevant intrinsic rate of natural increase (rm values). The analysis of variance
indicated that, regarding the last two parameters, there were significant differences
(P<0.05) between the varieties. The highest (43.21±5.45) and the lowest (34.43±8.91) average
numbers of progeny within the first 10 days were observed in those reared on the
Sardari and Zarrin varieties respectively but the figures obtained within the first 15 days
were found to be 49,43±13.31 on Alamoot and 58.86±9.45 on Sardari. Also the highest
mean “rm” value (0.3399±0.01) was estimated for rearings on Sardari with the smallest
(0.2889±0.03) on the latter. At present, Sardari seems to be more likley susceptible to the
aphid amongst the others. Field trials and experiments on later phenological stages of the
wheats and potential role of other resistance mechanisms is going on.