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) 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)

Abstract

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 PThe 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
• cultura da batata
• Diabrotica speciosa
• resistência de planta
• Agrotis ipsilon
• Diabrotica speciosa
• plant resistence
• potato crop