EFFECTS OF PRECONDITIONING HOST PLANTS ON POPULATION DEVELOPMENT OF RUSSIAN WHEAT APHIDS (HOMOPTERA, APHIDIDAE)

The effect of preconditioning hosts of Russian wheat aphid, Diuraphis noxia (Mordvilko), was evaluated. Three consecutive generations produced about twice as many progeny on 'Stephens' wheat as on 'Border' oats with preconditioning on 'Stephens' wheat. In the second and third generations, if the preceding generation had developed on 'Border' oats, there were significant reductions in the number of aphids produced. Smallest numbers of Russian wheat aphid progeny were produced in the third generation when two preceding generations were reared on 'Border' oats. Preconditioning of aphids is crucial if detailed responses of aphids or plants are to be noted, as in the evaluation of host plant resistance mechanisms.