Bioprotective potential of maize apoplastic fluid bacterium (Bacillus amyloliquefaciens) and arbuscular mycorrhizal fungi (Glomus intraradices) against Spodoptera frugiperda infestation in maize

Abstract

Spodoptera frugiperda is an invasive polyphagous pest of cereal crops and responsible for less maize production in the past. Development of bioprotective agents to reduce the impact of this biotic stress is essential. The present investigation was done to evaluate whether co-inoculation of maize with two endophytes such as Bacillus amyloliquefaciens and Glomus intraradices could alter the level of antioxidants and defense enzymes in maize and affect the feeding behavior of S. frugiperda on maize. The results indicated higher activity of antioxidants (catalases - 106.26%, peroxidases - 62.71%, superoxide dismutase −17.39% and ascorbate oxidase - 160.00%) and defensive enzymes (polyphenol oxidases - 205.86%, phenylalanine ammonia lyases - 126.00% and lipoxygenases - 33.33%) in leaves of B.amyloliquefaciens and G.intraradices treated maize after fed with S. frugiperda (96 h) over control. The total phenolics and dry biomass content were also higher in B. amyloliquefaciens and G. intraradices inoculated plants after S. frugiperda infestation (96 h). Leaf feeding bioassay indicated reduction in relative consumptive rate (18.25%), relative growth rate (19.76%) and increased feeding deterrence index (15.50%) of S. frugiperda when fed on B. amyloliquefaciens and G. intraradices inoculated maize for 24 h Inoculation of maize with B. amyloliquefaciens and G. intraradices significantly altered the defense parameters of maize which are directly linked with reduced feeding and growth rate of S. frugiperda. Therefore, these endophytes can be used to reduce the usage of chemical insecticides or be a part in integrated pest management systems for sustainable agriculture production.