REPRODUCTION OF RHOPALOSIPHUM PADI (HEMIPTERA: APHIDIDAE) ON DIFFERENT WHEAT CULTIVARS FROM SOUTHWEST OF BUENOS AIRES, ARGENTINA

Abstract

Triticum aestiuum L. is the main winter cereal in the southwestern región of Buenos Aires. Aphids are a major pest from implantation to crop harvest, limiting crop production. In recent years, Rhopalosiphum padi “bird cherry-oat aphid” has been detected in wheat. Knowledge of biology and potential population growth is crucial for studying its dynamics and
establishing management tactics for pest control. The main objective of this research was to determine the effects of different wheat cultivars on biological and population parameters of R. padi. Seeds of each wheat cultivar (ACA 303, ACA 302, ACA 223. Klein Gavilán, Klein Capricornio, Klein Tauro, Klein Tigre, Buck Meteoro, Buck 75aniversario and Buck Baqueano)
were planted individually in 250cc pots. 20 adult aphid were placed on the leaf surface, each confined inside a clip cage to prevent escape and parasitism. They were permitted to produce nymphs for 24 h and then the adult aphids were eliminated from the leaf clip cage. Each plant received one aphid nymph that was confined to the first true leaf. These nymphs were
monitored daily. After maturity and the beginning of reproduction, adult mortality and fecundity were recorded daily, and the offspring were removed from each leaf cage until each adult aphid died. Nymphal, pre-reproductive, reproductive and post reproductive periods were calculated using the program PERIOD. The survival rate for adults from birth to age x (lx) and
fecundity (mx) were measured. From these data, the net reproductive rate (R0), intrinsic rate of increase (rj, total reproductive valué (VRT), mean generation time (TG), finite rate of increase (X), , and doubling time (D) were estimated with software program TABLAVI. Data were analyzed by ANOVA and LSD (p < 0,05). Results indicated that wheat cv Buck 75 Aniversario had a shorter reproductive period, the lowest rm valué and a brief mean generation time, therefore the doubling time was longer than in the rest of the wheat cultivars. In conclusión, more studies on this wheat cultivar should be conducted on the possibility of finding genes involved in resistant to R. padi.