The shoot and fruit borer, Earias vittella is one of the major polyphagous pest prefer various host plants attacking almost 38 plant species and causes yield loss of 15-45% in vegetable crops annually in India. In this study Entomopathogenic bacteria (EPB) were used for biocontrol larvae of Earias vittella under in vitro condition. Whole cell culture and cell supernatant of EPB was screened for insecticidal activity against the larvae and results has shown that the lethality of larvae started after 12-24h of treatment. The percent mortality treated with intact cell was significantly higher in larvae treated with EPB3 with 90% mortality at 72h followed by EPB1 and EPB3. The larvae treated with cell supernatant of EPB had shown lethality in the range of the mortality of larvae where in the range of 50-70% at 72h of treatment and there was no significant difference among the bacteria treated. The LD50 value represent the concentration of cells required for the 50% population to be lethal and EPB3 had expressed significantly lower concentration of 4.28x10 4 CFU / ml followed by EPB9 and EPB8. The LD50 value for the larvae treated with cell supernatant were in the range of 10 10 to 10 12 CFU / ml. The larvae treated with EPB3 cell culture has taken significantly less time for mortality of fifty percent of population with a media lethal time (LT50) of 24h followed by EPB1 (30h) and EPB8 (32h). Among all the isolates EPB3 (Xenorhabdus nematophila) and EPB1 (Photorhabdus luminescens) had more virulence against the Earias vittella and can be further tested for biocontrol efficiency under greenhouse and field conditions.

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An investigation study was carried to test the ability of endophytic bacteria isolated from small millets as a biocontrol agent against the fungal pathogen Pythium aphanidermatum, the causal organism of sheath blight in foxtail millet (Setaria italica L.) grown in seedling trays under greenhouse conditions. In total twelve bacterial endophytes were isolated out of which six isolates produced β -1, 3 glucanases, 11 isolates produced chitinases and 12 isolates produced siderophores under in-vitro conditions. All these bacterial endophytic isolates inhibited mycelial growth of Pythium aphanidermatum in plate assay and liquid culture and the highest percent inhibition of mycelium was recorded in KMS5 (44.44%) followed by KMS1 (38.89%). In seedling Reddy et al.; CJAST, 38(6): 1-14, 2019; Article no.CJAST.52777 2 trays, BMR7 and KMS5 (81.66%) had recorded the highest percent germination followed by KMS1 (79.62%) and KMS1 and KMS5 took 10.85 and 10.55 days respectively for 50% seed germination compared to control (13.50 days) which was treated with pathogen alone. Lowest pre-emergence disease incidence was noticed in KMS5 (14.03%) followed by KMS1 (16.18%) whereas T1 (Control) recorded maximum pre-emergence disease incidence (39.82%) was observed. Least post-emergence disease incidence (11.36) and biocontrol efficacy (68.74%) was recorded with KMS5. Apart from showing antagonistic activity, KMS5 had recorded a significantly higher seedling vigor index (2712.97), root length (18.12 cm), shoot length (15.10 cm), root dry weight (0.158 g) and shoot dry weight (0.76 g) compared to other bacterial endophytic isolates. Original Research Article

The tobacco caterpillar, Spodoptera litura is a polyphagous pest with attacking almost 290 host plants species globally causing a wide range of yield losses to the agricultural crops. In this investigation symbiotic bacteria of entomopathogenic nematodes were evaluated for their insecticidal activity against larvae of S. litura under lab conditions. The intact cell suspension and cell-free extract were screened for their bacterial pathogenicity and the results showed mortality of larvae after 24h of post treatment. The percent mortality treated with intact cell suspension was significantly higher in larvae treated with EPB3 strain with 90% which was on par with the reference strain Bacillus thuringiensis after 72h of post treatment. There is no significant difference among the larval mortality treated with cell-free supernatant. The virulence test was carried out to find out the LD50 and LT50 against the larvae and the results showed that EPB3 and B. thuringiensis required 104 CFU for 50% lethality of larvae with a media lethal time of 24h and 22h, respectively when treated with cell suspension. In case of larvae treated with cell-free extract, LD50 value with 105-106 CFU with a median lethal time ranging from 33-45h. The results showed that the isolates EPB3 (Xenorhabdus nematophilus) is comparatively more virulent than other Photorhabdus isolates against the test insect S. litura. Further these symbiotic bacteria can be screened for their biocontrol efficiency under greenhouse and field conditions and can be developed as potential biopesticides against the insect pests.

The present study was carried out to test the biocontrol potential of symbiotic bacteria, Photorhabdus and Xenorhabdus against the shoot and fruit borer, Helicoverpa armigera in solanaceous vegetable crops grown under greenhouse conditions. A total of ten treatments were designed with symbiotic bacteria of entomopathogenic nematodes for testing their biocontrol potential by using Bacillus thuringiensis as a reference strain. The results had shown significantly higher biocontrol efficiency in the treatment T9 (H. armigera + Consortia) with 85-90% biocontrol efficiency in all the vegetable crops followed by the treatment T7 received Bacillus thuringiensis. Among the treatments received individual strains of entomopathogenic bacteria, T3 and T2 which received EPB3 and EPB1 with 75-80% biocontrol potential and are at par with each other. Other treatment received individual strains had shown more than 50% of biocontrol efficiency in vegetable crops grown in seedling trays under greenhouse conditions. Further these entomopathogenic bacteria can be tested for their effectivity under field trails and can be developed as bio-pesticide formulations either in the form of individual application or in integrated pest management for plant protection practices.