G. P. Uma ¹, A. Prabhuraj ¹, M. B. Patil ¹

Affiliations
1 Department of Agricultural Entomology, College of Agriculture, UAS, Raichur 584 102, Karnataka, IN

Abstract

Antibiotic and antagonistic effects of primary and secondary forms of Photorhabdus luminescens, a symbiotic bacterium of an entomopathogenic nematode Heterorhabditis indica (RCR) were investigated in vitro against plant pathogens and beneficial microorganisms. An inhibition zone assay on potato dextrose agar (PDA) medium revealed that the primary form completely inhibited all plant pathogenic fungi, viz., Aspergillus flavus, Rhizoctonia solani and Fusarium solani and tested secondary form completely inhibited the growth of F. solani and partially inhibited A. flavus and failed to inhibit R. solani. However, dual culture assay on nutrient agar (NA) in both forms completely inhibited the growth of the bacterial pathogen, Xanthomonas punicae. The forms of P. luminescens did not inhibit the mycelial growth of entomopathogens viz., Metarhizium anisopliae, Verticillium lecanii and Nomuraea rileyi but inhibited the growth of bacterial bioagents Rhizobium sp. and Pseudomonas fluorescens. The present study indicates that P. luminescens can be effectively used in the management of these plant pathogens.

Keywords

Antifungal, Antibacterial, Entomopathogens, Heterorhabditis, Photorhabdus luminescens, Plant Pathogens.

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A. Prabhuraj ¹, K. S. Girish ¹, Shivaleela ¹, B. V. Patil ¹

Affiliations
1 Department of Entomology, College of Agriculture, Raichur, 584101, Karnataka, IN

Abstract

A successful management strategy was developed against chickpea pod borer, Helecoverpa armigera (Hub) by integrating locally isolated entomopathogenic nematode, Heterorhabditis indica (RCR) with other entomopathogens like Helicoverpa armigera nuclear polyhedrosis virus (HaNPV) and Bacillus thuringiensis (Bt) and botanicals. Preliminary laboratory studies were conducted, to standardize the optimum dosage of nematodes required for field application, to evaluate the compatibility of nematode with entomopathogens and botanicals and their combinations. The optimum dosage of infective juveniles was standardized to third (LC₅₀ of 145 IJs/larva) and fourth (LC₅₀ of 195 IJs/larva) instars based on the concentration mortality response. Persistence study on chickpea foliage in field condition indicated that, infective juveniles along with 0.1 % glycerol survived better (80%) compared to other anti-dcssicants. In compatibility studies, though H. indica was compatible with other entomopathogens, but was susceptible to higher concentrations of aqueous leaf extracts of some selective botanicals. A series of laboratory bioassay was carried out to select best combinations of H. indica with other entomopathogens and botanicals against third and fourth instar H. armigera and these were tested in field for two consecutive years. Two year field evaluation indicated that, sequential application of H. indica + Prosopis juliflora (1 lakh IJs/I + 10%) at 50 and 75 days after sowing was superior with highest larval reduction (23.47%), minimum pod damage (11.27%) and maximum seed yield (19.24 q/h).

Keywords

Heterorhabditis indica, Helicoverpa armigera, Management, Chickpea, Botanicals, HaNPV, Entomopathogens, Mortality.

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A. Prabhuraj ¹, B. V. Patil ¹, K. S. Girish ¹, Shivaleela ¹

Affiliations
1 Department of Entomology, College of Agriculture, Raichur, 584 101, Karnataka, IN

Abstract

A field experiment was conducted at Agricultural College, Raichur, Karnataka to evaluate the effect of Heterorhabditis indica (RCR), an insect parasitic nematode in combination with other entomopathogens and botanicals against Helicoverpa armigera (Hübner) in chickpea ecosystem. Pooled data on per cent larval reduction after two sprays revealed that the highest reduction of 47.63 was achieved in chlorpyriphos/quinalphos (0.04/0.05%) treatment at seven days after spraying. However, sequential application of H. indica + Pa. pinnata (1.0 lakh IJs +2.5%) and H. indica + Pr. juliflora (1.0 lakh Us +10%) recorded maximum yield (1.96 and 1.83 kg/plot, respectively) with minimum pod damage (10.9 and 11.5 %, respectively). Thus there is a scope for integration of H. indica with botanicals viz. Pa. pinnata and Pr. juliflora for the effective management of chickpea pod borer.

Keywords

Bacillus thuringiensis, Heterorhabditis indica, Larval Reduction, Pongamia pinnata, Prosopis juliflora, Seed Yield.

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A. Prabhuraj ¹, B. V. Patil ¹, Shivaleela ¹, K. S. Girish ¹

Affiliations
1 Department of Entomology, College of Agriculture, University of Agricultural Sciences, Raichur 584 101, Karnataka, IN

Abstract

The bio-efficacy of Heterorhabditis indica Poinar in combination with Helicoverpa armigera nuclear polyhedrosis virus (HaNPV) against Helicoverpa armigera (Hiibner) was evaluated during 2002 in the laboratory. Results revealed thut combination of H. indica and HaNPV at all concentrations recorded highest mortality (100%) and were on par with alone inoculation of H. indica treatment, but significantly superior over HaNPV alone against third instar larva. Fourth instar larva suffered cent per cent mortality when inoculated with H. indica plus HaNPV at all concentrations after 48 h compared to H. indica alone (@ 200 Usl larva) which recorded 75 per cent mortality. The results indicate the synergistic effect when both the bioagents were combined against fourth instar larva.

Keywords

Entomopathogenic Nematode, HaNPV, Helicoverpa armigera, Heterorhabditis indica, Infective Juvenile.

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A. Prabhuraj ¹, C. A. Viraktamath ², A. R. V. Kumar ²

Affiliations
1 Department of Agricultural Entomology, College of Agriculture Raichur 584 101, Karnataka, IN
2 Department of Entomology, University of Agricultural Sciences, GKVK Bangalore 560 065, Karnataka, IN

Abstract

A modified trapping technique for the entomopathogenic nematodes was tested for its efficacy in recovery of naturally occuring insect parasitic nematodes, optimum time of removal of baited traps from the soil and at the same time prevention of attack by predatory ant,Solenopsis geminata (Fabr.). The highest nematode recovery (13.5 %) and the least ant attack were achieved on fourth day of trapping. Modified trapping technique was found effective in the prevention of predatory ant attack which subsequently increased the efficacy of nematode recovery.

Keywords

Chlorpyriphos, Entomopathogenic Nematodes, Gellaria mellollella, Solenopsis geminata.

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Saroja ¹, Basavaraj Kalmath ¹, M. Bheemanna ², A. Prabhuraj ²

Affiliations
1 College of Agriculture, Bheemarayanagudi, Shahapur, Yadgiri - 585287, Karnataka, IN
2 College of Agriculture, UAS Raichur - 584104, Karnataka, IN

Abstract

Radiation severely inactivates the potency of Bacillus thuringiensis spores and crystals present in sprayed formulations leading to decreased efficacy in field. Incorporation of UV protectants to biopesticides is one of the methods to protect against radiation damage. Keeping this as objective, a native isolate BGC-1 was selected for preparation and evaluation of wettable powder formulation against second instar larvae of Helicoverpa armigera. Median lethal concentration of the BGC-1 was 1.05 g/l and assigned biopotency value was 15428.57 ITU/g. UV protectants viz., melanin, para-amino benzoic acid, polyvinyl alcohol and Congo red were evaluated by exposing formulated solution to sunlight at different intervals of time. Among four UV protectants, melanin showed an excellent UV protecting ability with the mortality of 86.67 per cent and, 116.49 μg/ml of crude protein at 5 h sunlight exposure with temperature of 43.6°C and light intensity of 4.93×10⁵ lux followed by 80.00 per cent mortality, 1.74×10⁸ CFU/ml and 109.40 μg/ml of crude protein in para-amino benzoic acid UV protectant. Next best UV protectant was congo red with the mortality of 73.33 per cent and, 90.76 μg/ml of crude protein and 1.26×10⁸ CFU/ml. It is concluded that melanin was found to be an effective UV protectant for B. thuringiensis WP formulations against H. armigera.

Keywords

Bacillus thuringiensis, Helicoverpa armigera, Lyophilized Powder, WP Formulation, UV Protectants.

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