Demographic Assessment of Plant Cultivar Resistance To Insect Pests: a Case Study of the Dusky-Veined Walnut Aphid (Hemiptera: Callaphididae) on Five Walnut Cultivars

Abstract

To provide a comprehensive evaluation of walnut cultivar resistance to the dusky-veined walnut aphid, Panaphis juglandis (Goeze), we collected the life table data of this aphid reared on five cultivars of walnut ('Akca I,' 'Chandler,' 'Fernette,' 'Fernor,' and 'Pedro') under field conditions. The raw data of the developmental time, survival rate, and fecundity was analyzed using the age-stage, two-sex life table to account for the variable developmental rate and stage differentiation among individuals. Due to the species' longer immature developmental time, shorter adult longevity, shorter reproduction period, and lower fecundity, the net reproduction rate (R-0 = 5.9 offspring), intrinsic rate of increase (r = 0.0983 d (1)), and finite rate (lambda = 1.1034 d (1)) were the lowest when aphids were reared on the Fernor cultivar, while those reared on Akca I exhibited the highest population parameters (R-0 = 18.0 offspring, r = 0.2031 d(-1), and lambda = 1.2252 d(-1)). Based on the population characteristics, Fernor is a less favorable cultivar for the development and reproduction of P. juglandis. We also demonstrated the advantages of using bootstrapping for the analysis of standard errors of developmental time, longevity, fecundity, and other parameters as well. Our results indicated that demographic analysis of pest development, survival, and reproduction based on the agestage, two-sex life table offers a comprehensive assessment of pest growth potential on different crop cultivars.