Age-Specific Life Table Modeling of the Russian Wheat Aphid (Homoptera: Aphididae) on Barley Grown in Benzimidazole Agar

Abstract

Age-specific life table studies were conducted on the Russian wheat aphid, Diuraphis noxia (Mordvilko), to evaluate the effects of using a barley–benzimidazole agar system on D. noxia growth, reproduction, and survival. Weibull functions, linear and nonlinear regression, a modified Sharpe and DeMichele biophysical model (MSDBM), and Maxima functions were used to estimate or model survivorship patterns, the lower temperature threshold for development, the upper temperature inhibition threshold, nonlinear aspects of rates of development, and mean daily fecundity patterns of D. noxia , respectively. The Weibull function provided a good fit to the aphid survivorship patterns (R2 = 0.95). The lower developmental threshold and the upper temperature inhibition threshold for the Russian wheat aphid using the barley–benzimidazole agar system were estimated to be 5.2 and 30.3°C, respectively. The MSDBM also provided an excellent fit to nonlinear aspects of developmental rate trends (R2 = 0.996). Maxima functions were found to adequately describe patterns of daily fecundity at 3 of the 4 constant temperatures examined. The mean longevity of D. noxia reared on the barley–benzimidazole agar system was greater than those reported by other authors using wheat- and rye-benzimidazole agar systems. Longer nymphal devplopment times using the barley–benzimidazole agar system resulted in a lower intrinsic rate of increase for Russian wheat aphids reared at 19.5°C, than those observed by other authors using wheat- and rye-benzimidazole agar systems, and a developmental threshold that was higher than those reported by other authors for Russian wheat aphids grown on wheat using other plant growth systems.