RUSSIAN WHEAT APHID (HOMOPTERA, APHIDIDAE) PERFORMANCE ON PERENNIAL GRASSES

Russian wheat aphid, Diuraphis noxia (Kurdjumov), survival and fecundi ty on 25 perennial grasses in their 1st yr of growth was measured in g reenhouse experiments. Thirteen grasses that had survived heading, see d set, and induced dormancy were tested for aphid host suitability of plants in their 2nd yr of growth. In general, wheatgrasses were the mo st suitable Russian wheat aphid hosts in both 1st- and 2nd-yr growth e xperiments. Siberian wheatgrass P-27 and crested wheatgrass 'Ephraim' were better hosts for the Russian wheat aphid 1 yr after establishment than in the 1st yr; however, there was no difference in host suitabil ity between concurrently tested 1st- and 2nd-yr plants. Great Basin wi ldrye 'Magnar' was a less suitable host in the second year, but this p erennial grass was a poor host over all plant ages. These greenhouse r esults support the conclusion that certain perennial grasses that are suitable for Russian wheat aphid survival and fecundity in the 1st yr of growth remain so in second and subsequent years following establish ment. For acreage set aside in the Conservation Reserve Program, it is advisable to plant perennial grasses that are poor Russian wheat aphi d hosts from the outset.