Resistance elicitors and defense response enhancers of maize to Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae)

Abstract

The objective of this research was to assess the potential of abiotic compounds as defense response enhancers in maize using enzymatic quantification and their efficiency in reduction of damages caused by S. frugiperda. The experiment was laid out in a randomized complete block design with six treatments and five replications. The treatments were: T1: positive control (distilled water + infestation); T2: negative control (without product application, uninfested); T3: biofertilizer; T4: acibenzolar-S-methyl (ASM); T5: potassium silicate; T6: potassium silicate + ASM. The treatments were applied in V6 stage of maize plants. After five days, the plants were artificially infested with 2nd instar caterpillars of S. frugiperda. Damage assessments were carried out at 4, 8, 16 and 22 days after infestation using a scale of notes. To evaluate the enzymatic activity, one leaf of each plant was removed at 2, 4, 8, 16 and 22 days after infestation. The largest peroxidase activities were observed at two DAI (days after infestation) using the potassium silicate + ASM (2,344.12 UAE.mg -1 of proteína.min -1 ) treatment, while the larger polyphenol oxidase activity peaks were observed after treatment with ASM at 22 DAI. The application of potassium silicate + ASM in corn plants can promote peroxidase activity. The polyphenol oxidase activity was increased after application of ASM, whereas the presence of the pest (on positive control) could potentially increase the activity of phenylalanine ammonia-lyase. The applications of ASM alone and potassium silicate + ASM contributed to reduction of the foliar damage level caused by S. frugiperda in corn plants.

Ecophysiological responses of ´Turiaçu´ pineapple plants at vegetative and reproductive stages to soil fertilization and crop location

“…The biofertilizer was produced by the State University of Maranhão and has potential for pest and disease control (MONDEGO et al, 2018;MONDEGO et al, 2019). This biofertilizer was prepared by an anaerobic fermentation process, with the following formulation for 10 L: 2.00 kg of bovine manure, 0.20 kg of ground sugarcane, 0.10 kg of ash, 0.10 kg of ground phosphate rock, 0.05 kg of boric acid, 0.04 kg of zinc sulfate, and 0.20 L of bovine milk.…”