Indução de resistência com silicato de potássio em Handroanthus chrysotrichus (Mart. ex DC) Mattos (Bignoniaceae) para o controle de Dorynota (Dorynota) parallela, Blanchard, 1837 (Coleoptera: Chrysomelidae)

Abstract

The production of Handroanthus chrysotrichus (Mart. Ex DC.) Mattos (ipê-yellow) free from the defoliant attack caused by the Dorynota (Dorynota) parallela Blanchard, 1837 beetle is relevant so that the plant does not have the compromised vigor. The addition of potassium silicate in H. chrysotrichus presents a sustainable alternative of control to the insults caused by insects. The objective of this study was to evaluate the level of damage by D. parallela on trees of H. chrysotrichus inserted in the landscaping and evaluation of foliar consumption by D. parallela Blanchard, 1837 in H. chrysotrichus seedlings as an alternative of control conferred by the possible induction of Resistance in the plant. The percentage of damage of D. parallela in H. chrysotrichus trees was evaluated by assigning visual notes related to the variation of 0 to 100% of defoliation. The yellow ipê seedlings were produced from seeds collected at the Federal University of the Recôncavo da Bahia and transplanted later to 8L containers and kept under a screen. Potassium silicate was used in the doses 0.63 mL; 1.25mL; 1.87mL; 2.19mL and 2.5mL; All diluted in 2.5L of water and in the water-only control, composing the completely randomized design with six treatments and ten replicates. In the greenhouse, each insect was placed on the surface of the leaflet of the middle region of the plant and protected by an anti-aphid screen. The area consumed (cm2) by the insect was evaluated at the end of 24 hours for three consecutive days through the scanning of the leaflet and later analysis in Image J. Software. It was analyzed by the Scott-Knott test, at 1% probability, using the ASSISTAT statistical program Version 7.7. The percentage of damage of D. parallela in H. chrysotrichus trees was evaluated by assigning visual notes related to the variation of 0 to 100% of defoliation. Among the doses applied, the seedlings that received the solution containing 1.25mL of potassium silicate significantly reduced foliar consumption by D. parallela with a mean of 0.69 cm2 of area consumed in 24 hours, while the seedlings that Did not receive potassium silicate showed the highest average consumption (2.26 cm2). The evaluation of the percentage of damage showed that in June the plants had levels of defoliation more intense than in January. It was concluded that silicon can contribute to the resistance induction in H. chrysotrichus to the attack of D. parallela and in rainy months the percentage of damage is superior to H. chrysotrichus.