Biologia de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) em Algodoeiro de Fibra Colorida Tratado com Silício

Abstract

A lagarta Spodoptera frugiperda (Smith) é praga-chave da cultura do milho e a cada ano sua ocorrência na cultura algodoeira têm aumentado, causando danos severos desde a fase de plântula até a maturação. Objetivou-se com este trabalho avaliar o efeito do silício na biologia de S. frugiperda em algodoeiro de fibra branca e colorida. Os bioensaios foram conduzidos com duas cultivares de algodão, a BRS Cedro (fibras brancas) e BRS Verde (fibras verdes), com e sem aplicação de silício. O silício foi aplicado como solução de ácido silícico a 1 %, na dosagem equivalente a 3 t/ha de SiO2. Avaliaram-se os seguintes parâmetros biológicos: mortalidade larval, duração da fase larval e pupal, viabilidade de pupa, peso das pupas, razão sexual, longevidade dos adultos, machos e fêmeas e o número de ovos/fêmea. Verificou-se que a aplicação de silício aumentou apenas a mortalidade de lagartas alimentadas com folhas da BRS Cedro, não demonstrando nenhum efeito nas lagartas quando aplicado na BRS Verde. Além disso, na cultivar BRS Cedro, em comparação com a cultivar BRS Verde, houve menor peso de pupa e menor produção de ovos/fêmea.
 Biology of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in Colored Cotton Treated with Silicon
 Abstract. The caterpillar Spodoptera frugiperda (Smith) is a key pest of the corn culture and each year its occurrence in the cotton culture has increased, causing severe damage from the seedling phase to maturation. The objective of this work was to evaluate the effect of the silicon on the biology of S. frugiperda in white and colored fiber cotton plants. The bioassays were conducted with two cultivars of cotton, BRS Cedro (white fibers) and BRS Verde (green fibers), with and without silicon application. The silicon was applied as a solution of 1% silicon acid, at a dosage equivalent to 3 ton/ha of SiO2. The following biological parameters were evaluated: larval mortality, duration of the larval and pupal phase, pupal viability, pupal weight, gender ratio, adult longevity of males and females and the number of eggs/female. It was verified that the silicon application only increased the mortality of caterpillars fed with BRS Cedro leaves, not demonstrating any effect on the caterpillars when applied on BRS Verde. Furthermore, the BRS Cedro cultivar, when compared to the BRS Verde cultivar, presented a lower pupal weight and a lower eggs/female production.

Silicon-based induced resistance in maize against fall armyworm [Spodoptera frugiperda (Lepidoptera: Noctuidae)]

“…Insect fecundity is one of the biological parameters most affected by Si. Silva et al [ 38 ] reported that male-female pairs of fall armyworm derived from larvae fed on cotton leaves treated with Si produced fewer eggs per female. At the same time, He et al [ 39 ] demonstrated that feeding with rice plants treated with Si solution significantly reduced the fecundity of Nilaparvata lugens (Stal).…”

Induction of resistance of corn plants to Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) by application of silicon and gibberellic acid

“…Silva et al . (2014) reported that male–female pairs of S. frugiperda derived from larvae fed on cotton leaves treated with silicon produced fewer eggs per female, while He et al . (2015) demonstrated that feeding with rice plants treated with silicon solution significantly reduced the fecundity of Nilaparvata lugens (Stål).…”

Effect of resistance elicitors on the biology and feeding preference of Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) in corn

“…These results corroborate with studies conducted by Nascimento et al (2018), which showed reduced viability and numbers of eggs of S frugiperda females fed with silicon treated plants applied both by leaf and soil. Silva et al (2014) observed that the application of silicon in cotton promoted a reduction in the production of eggs / female of S. frugiperda. ASM acts as an activator of the plant's natural defenses against pests and diseases (Tomquelski et al, 2007).…”