COMPARISON OF THE DEVELOPMENT AND FECUNDITY OF RUSSIAN WHEAT APHID (HOMOPTERA, APHIDIDAE) IN SOUTH-AFRICA AND HUNGARY

Several life history parameters (nymphal development time, prereproduc tive period, reproductive period, postreproductive period, total life span, total fecundity, and age-specific natality) of Diuraphis noxia ( Mordvilko) from South Africa and Hungary were compared on 2 South Afri can wheat varieties ('Betta', which is D. noxia-susceptible, and 'SST 333', which is D. noxia-resistant) and 1 Hungarian spring barley varie ty ('Isis', which is D. noxia-susceptible). Nymphal development time, reproductive period, and total life span were significantly longer in Hungary than in South Africa. South African nymphs developed to adults between 9.3 and 9.7 d, whereas those in Hungary took 10.7-11.1 d (the ranges indicate variation in mean values among host plant species). T he adult reproductive period lasted 22.9-24.0 d in South Africa and 35 .2-37.1 d in Hungary. Total life span was 41.7-45.2 d in South Africa and 52.0-52.2 in Hungary. Total fecundity was significantly higher in South Africa (67.1-75.1) than in Hungary (53.0-62.2) on Betta, SST 333 , and Isis. Hungarian D. noxia not only produced fewer nymphs but took much longer to do so; therefore, it is possible that the Russian whea t aphid in South Africa would reach economic thresholds in the field s ooner than in Hungary.