Induction of Resistance by Silicon in Wheat Plants to Alate and Apterous Morphs of Sitobion avenae (Hemiptera: Aphididae)

Despite the knowledge about the effects of silicon augmenting antibiosis and nonpreference of plants by apterous aphids, few studies exist on such effects with alate aphids. This study evaluated the effects of silicon fertilization on the biology of alate and apterous morphs of Sitobion avenae (F.) (Hemiptera: Aphididae), and the effect on nonpreference by S. avenae alates for wheat plants with or without silicon fertilization. A method for rearing aphids on detached leaves was evaluated comparing the biology of apterous aphids reared on wheat leaf sections and on whole plants with and without silicon fertilization. Because the use of detached leaves was a reliable method, the effect of silicon fertilization on the biology of apterous and alate S. avenae was assessed using wheat leaf sections. Biological data of aphids were used to calculate a fertility life table. Finally, the effect of silicon fertilization on the nonpreference of alate aphids was carried out for both vegetative and reproductive phases of wheat. Thirty alate aphids were released in the center of a cage, and the number of aphids per whole plant with or without silicon fertilization was observed. Silicon fertilization induced antibiosis resistance in wheat plants to apterous morphs as shown by reduced fecundity, reproductive period, longevity, intrinsic rate of increase, and net reproductive rate; however, alates were unaffected. Plants that received silicon fertilization had fewer alate aphids in both the vegetative and reproductive phases. Thus, silicon fertilization can reduce colonization by alates, enhancing nonpreference resistance, and population growth of apterous S. avenae in wheat plants.