Bacillus thuringiensis is the most widely used microbial bioinsecticide; however, only a few strains possess additional traits such as plant growth promotion and biocontrol potential. This study characterized 25 B. thuringiensis isolates obtained from soil and infected insect cadavers to identify multifunctional strains with insecticidal and plant growth‐promoting (PGP) properties. Microscopic examination revealed diverse parasporal crystal morphologies, while 16S rRNA sequencing confirmed their identity with 99%–100% similarity to reference strains. Enzymatic profiling showed protease activity in 24 strains and lipase activity in 21 strains, whereas all isolates produced lecithinase and chitinase. All strains produced indole‐3‐acetic acid (11.22–31.87 µg mL−1) and ammonia (26.74–77.68 µg mL−1), while phosphate solubilization and siderophore production were observed in 21 and 11 strains, respectively. Bioassays against Spodoptera frugiperda identified five highly virulent strains causing more than 90% larval mortality. Among these, NBAIR Bt25 showed the highest efficacy, causing 92% mortality within 96 h with an LC50 of 39.75 µg mL−1. PCR analysis revealed that NBAIR Bt25 carries multiple pesticidal genes (cry1A, cry1D, cry1E, cry1I, cry2A, and vip3A). Paper towel and glasshouse assays demonstrated that strain NBAIR Bt25 significantly enhanced shoot growth and secondary root development. Overall, NBAIR Bt25 emerged as a promising multifunctional strain with strong insecticidal activity, plant growth‐promoting ability, and biocontrol potential, making it a suitable candidate for sustainable pest management and climate‐smart agriculture.
Manjunatha Channappa, Aditya Kukreti, L. Manjunath et al.· Journal of Basic Microbiolog...· 0 citations
Spodoptera frugiperda
(J.E. Smith), commonly known as the fall armyworm, is one of the most destructive insect pests of maize worldwide, causing substantial economic losses. Its widespread occurrence and increasing resistance to conventional insecticides have intensified the need for effective and sustainable management approaches. Reliance on chemical pesticides not only accelerates resistance development but also poses significant risks to the environment and beneficial non-target organisms. Consequently, environmentally friendly alternatives, particularly biological control strategies, are gaining importance as viable components of integrated pest management programs for this pest.
In the present study, the susceptibility of the larval and pupal stages of
S. frugiperda
to two indigenous entomopathogenic nematode (EPN) species,
Steinernema shori
NBAIRS80 and
Steinernema indicum
NBAIRS58, was assessed. The effect of different concentrations of infective juveniles (IJs) of
S. indicum
and
S. shori
on their reproductive potential in third-instar
S. frugiperda
larvae was also investigated under laboratory conditions. Furthermore, the efficacy of
S. indicum
and
S. shori
against
S. frugiperda
was evaluated under both pot and field conditions.
Results revealed that under laboratory conditions, both EPN species exhibited high virulence against third, fourth, and sixth instar larvae, achieving 100.0% mortality as the concentration increased from 20 to 420 IJs larva
-1
. However,
S. shori
caused significantly higher mortality than
S. indicum
. A similar trend was recorded in pupae, where
S. shori
caused 81.0% mortality compared to 65.0% by
S. indicum
. Both species were able to penetrate the larvae and complete their life cycles, producing a higher number of infective juveniles (IJs). However, in both species, penetration declined significantly at higher IJ concentrations. Although emamectin benzoate performed better than both EPN species under both pot and field conditions,
S. shori
showed improved performance in reducing larval populations after the second round of spraying.
Considering its effectiveness and environmental safety, the present study highlights the potential of
S. shori
as a biological control agent against the larval and pupal stages of
S. frugiperda.
Future studies should evaluate its efficacy against other economically important insect pests and assess its performance under diverse environmental conditions to support its wider field application.
J. Patil, Aarthi Nekkanti, Omprakash Navik et al.· Frontiers in Plant Science· 0 citations