Impacto dos nutrientes N e K e de açúcares solúveis sobre populações de Diabrotica speciosa (Germar) (Coleoptera, Chrysomelidae) e Agrotis ipsilon (Hüfnagel) (Lepidoptera, Noctuidae) na cultura da batata, Solanum tuberosum L. (Solanaceae)

Abstract

ABSTRACT. Impact of the nutrients N and K and soluble sugars on Diabrotica speciosa (Germar) (Coleoptera, Chrysomelidae) and Agrotis ipsilon (Hüfnagel) (Lepidoptera, Noctuidae) populations in potato crops, Solanum tuberosum L. (Solanaceae). The occurrence of Diabrotica speciosa (Germar, 1824) and Agrotis ipsilon (Hüfnagel, 1767) on the potato cultivars Achat and Monalisa, influenced by nitrogen and potassium dosage, and minimum theor of soluble sugars, was studied. The following parameters were evaluated: concentration of mineral nutrient and sugar in green leaf, senescent leaf, leaf in abscission, stem, tubercle and total plant using extracts of infusion in ethanol 80%. The largest infestation of D. speciosa larvae was on Monalisa cultivar at 150 kg.ha -1 of N + K with 27.03% at P< 0,05. It was observed that the effect of the dosage of N + K in the increment of the concentration of soluble sugars increased the damages in the tubercles and stems by A. ipsilon. The infestation by these species increased to 58.82% on the Monalisa cultivar, when the nitrogen dosage increased from zero to 150 kg.ha -1 , in the absence of potassium. On the other hand, high dosage of K reduced the damages by A. ipsilon on Monalisa cultivar. However, it did not influence the storage of soluble sugar. The results indicated that in Achat cultivar the accumulated soluble sugar was reduced, probably sensibilized by elevation of potassic fertilization dosing, differing from Monalisa cultivar, in which the influence was by nitrogen dosing. KEYWORDS.Agrotis ipsilon; Diabrotica speciosa; plant resistence; potato crop. RESUMO.Foi estudada a ocorrência de Diabrotica speciosa (Germar, 1824) (Coleoptera, Chrysomelidae) e de Agrotis ipsilon (Hüfnagel, 1767) (Lepidoptera, Noctuidae) em plantas de batata, cultivares Achat e Monalisa, influenciadas por dosagens de nitrogênio e potássio, e teor mínimo de açúcares solúveis. Os seguintes parâmetros foram avaliados: concentração de nutrientes minerais e açúcar em folha verde, folha senescente, folha em abcisão, haste, tubérculo e planta total usando extratos de infusão em etanol 80%. A maior infestação por larvas de D. speciosa foi na cultivar Monalisa a 150 kg.ha -1 de N + K com 27,03% a P<0,05. Foi observado que o efeito da dosagem de N + K no incremento da concentração de açúcares solúveis aumentou os danos provocados por A. ipsilon nos tubérculos e hastes. A infestação por essas espécies aumentou para 58,82% na cultivar Monalisa, quando a dosagem de nitrogênio foi elevada de 0 para 150 kg.ha -1 , na ausência de potássio. Por outro lado, alta dosagem de potássio reduziu os danos causados por A. ipsilon na cultivar Monalisa. Entretanto, não influiu no armazenamento de açúcar solúvel. Os resultados indicaram que na cultivar Achat os teores de açúcares solúveis foram reduzidos, provavelmente sensibilizados pela elevação da dosagem de adubação potássica, diferindo da cultivar Monalisa cuja influência verificada foi pela dosagem do nitrogênio. PALAVRAS-CHAVE.Agrotis ipsilon; cultura da batata; Diabrotica...

Influence of silicon on the development, productivity and infestation by insect pests in potato crops

“…The nutrients provided by organic compounds are less soluble and, therefore, less attractive to adult D. speciosa (DAROLT et al, 2003). In agreement with the results presented in this paper, a high incidence of D. speciosa has been reported on potatoes cultivated on substrates containing elevated levels of soluble nitrogen (AZEREDO et al, 2004), the presence of which probably give rise to an accumulation of free amino acids that attract insects (GLIESSMAN, 2001).…”

“…The adult beetles cause indirect damage by consuming the leaves of the potato plant, while during the larval stage direct damage reduces the value of the tubers (AZEREDO et al, 2004). In order to control the larvae, either liquid or granulated insecticide is normally applied during the cultivation cycle or incorporated into the potato mounds.…”

New national potato genotypes: yield response to different doses of 4-14-8 NPK fertilizer

“…The excess of fertilizer may increase the soluble sugar contents in potato, leading to an increase in the damage caused by Agrotis ipsilon (Lepidoptera, Noctuidae) on tubers and stems (Azeredo et al, 2004). Likewise, the increase in nitrogen may increase the incidence of Phytophthora infestans on the leaves of the plants (Bangemann et al, 2014).…”