Enzymatic Activity and Efficacy of Plant Growth Promoting Bacillus amyloliquefaciens on Feeding Behaviour of Spodoptera frugiperda on Maize

Maize is a third important cereal crop which has been heavily infested with the invasive pest Spodoptera frugiperda. An alternate biological mode of control is necessary instead of seeking inorganic chemical control. Plant endophytes could be of great option for controlling plant pathogens and pest. In this context, the present study aimed to evaluate the potential of Bacillus amyloliquefaciens isolated from maize (COH6) leaf apoplastic fluid. This bacterium was found to have plant growth promoting traits like indole acetic acid, siderophore, ammonia and hydrogen cyanide production. In addition, it was found to produce hydrolytic enzymes such as protease, pectinase, chitinase, and lipase which imply its bioprotective potential. Further foliar spray of B. amyloliquefaciens with cell concentration of 108 CFU ml-1 on 4 days old maize seed germination @ 5 ml per plant showed greater colonization percentage (8.30×108 CFU g-1 fresh leaf) over other doses (1, 2, 3 & 4 ml plant-1). The highest feeding deterrence was observed when Spodoptera frugiperda fed on leaves inoculated with 5 ml of B. amyloliquefaciens

Maize Apoplastic Fluid Bacteria Alter Feeding Characteristics of Herbivore (<i>Spodoptera frugiperda</i>) in Maize

Maize is an important cereal crop which is severely affected by Spodoptera frugiperda. The study aims to identify endophytic bacteria of maize root and leaf apoplastic fluid with bioprotective traits against S. frugiperda and plant growth promoting properties. Among 15 bacterial endophytic isolates, two strains—namely, RAF5 and LAF5—were selected and identified as Alcaligenes sp. MZ895490 and Bacillus amyloliquefaciens MZ895491, respectively. The bioprotective potential of B. amyloliquefaciens was evaluated through bioassays. In a no-choice bioassay, second instar larvae of S. frugiperda fed on B. amyloliquefaciens treated leaves (B+) recorded comparatively lesser growth (1.10 ± 0.19 mg mg−1 day−1) and consumptive (7.16 ± 3.48 mg mg−1 day−1) rates. In larval dip and choice bioassay, the same trend was observed. In detached leaf experiment, leaf feeding deterrence of S. frugiperda was found to be greater due to inoculation with B. amyloliquefaciens than Alcaligenes sp. The phenolics content of B. amyloliquefaciens inoculated plant was also found to be greater (3.06 ± 0.09 mg gallic acid g−1). However, plant biomass production was more in Alcaligenes sp inoculated treatment. The study thus demonstrates the potential utility of Alcaligenes sp. and B. amyloliquefaciens for improving growth and biotic (S. frugiperda) stress tolerance in maize