R. Nirmala ¹, B. Ramanujam ¹, R. J. Rabindra ¹, N. S. Rao ¹

Affiliations
1 Project Directorate of Biological Control (leAR) Post Bag No. 2491, H. A. Farm Post, Bellary Road Hebbal, Bangalore 560024, Karnataka, IN

Abstract

The pathogenicity of twelve fungal isolates belonging to Beauveria basiana (Bals.) Vuill., Metarhizium allisopliae (Metschinikoff) Sorokin and Verticillium lecanii (Zimmerman) against Aphis craccivora Koch, Aphis gossypii Glover and Rhopalosiphum maidis Fitch was studied using detached leaf bioassay technique. All twelve isolates of thc three fungi were found to be pathogenic to A. craccivora and A. gossypii at a concentration of 1x107 spores/ml. All isolates except Bb3 and Bb4 of B. bassiana were pathogenic to R. maidis. The mortality ranged from 2 to 74 per cent in A. craccivora, 14 to 80.8 percent in A. gossypii and 6 to 50 per cent in R. maidis. Bb5a isolate of B. bassiana caused highest per cent mortality in A. gossypii (80.8%.) and R. maidis (50%) indicating its broad spectrum action. VII isolate of V. lecanii recorded maximum mortality (80.8%) of A. craccivora. R. maidis was relatively less susceptible to the three fungi than A. craccivora and A. gossypii. The LC50 of Bb5a for three days old nymphs of A. gossypii was 6.57x105 spores/ml. The LT₅₀ of Bb5a for three days old nymphs of A. gossypii was highest (9.67 days) for the lowest dose of 106 spores/ml, which decreased with increasing concentration. The highest dose 109 spores/ml recorded the lowest LT₅₀ of 1.76 days.

Keywords

Aphis craccivora, Aphis gossypii, Beauveria bassiana, Metarhizium anisopiiac, Rhopalosiphum maidi, Verticillium lecanii.

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R. Nirmala ¹, B. Ramanujam ², R. J. Rabindra ², N. S. Rao ²

Affiliations
1 Entomology section, Sugarcane Breeding Institute, Coimbatore-641007, IN
2 Project Directorate of Biological Control (ICAR), Post Bag No. 2491, H. A. Farm Post, Bellary Road Hebbal, Bangalore, 560 024, Karnataka, IN

Abstract

Four isolates in each of Beauveria bassiana (Bals.) Vuill, Metarhizium anisopliae (Metschinikoff) Sorokin and Verticillium lecanii (Zimmerman) Viegas, pathogenic to key pests of crops like, coffee berry borer, coconut rhinoceros beetle, cashew stem borer, citrus and coffee green scale etc. were assessed for the colony growth on Potato Dextrose Agar (PDA), biomass and spore production in Potato Dextrose Broth (PDB) and dry spore production in rice grown through di-phasic production system. The isolates Bb5a (B. bassiana), Ma4 (M. anisopliae) and V15 (V. lecanii) were found fast growing with the colony diameter of 6.3, 8.1 and 5.7cm, respectively on PDA after 15 days of incubation. Biomass production in PDB was comparatively higher in shake cultures than in stationary cultures for all isolates except Bb4, BbSa, and V13a. Among the B. bassiana isolates, biomass production in stationary cultures was highest in Bb4 isolate (0.78 g/100ml) and in shake culture in Bb3 isolate (1.02g/100ml). Ma2 in stationary eulture (0.8g/100ml) and Ma3 isolate in shake cultures produced maximum biomass (l.09g/100ml). V1 2a isolate among V. lecanii isolates produced maximum biomass in stationary culture and shake culture (0.77 and 1.03g/100ml, respectively). M. anisopliae isolates formed mycelial pellets of various sizes under shake culture condition in PDB, In two-stage system of mass production, the maximum spore production on rice was observed in BbSa, Ma4 and V15 isolates (96.0, 49.8 and 17.5 x 10⁸ spores g⁻¹) and maximum spores per gram of rice were harvested in Bb5a, Ma2 and V12a isolates (28.00, 45.50 and 15.60 mg g⁻¹). Maximum viable spores per gram of spore dust were recorded in Bb5a, Ma4 and V15 isolates (4.7 x 10¹⁰, 2.5 x 10¹⁰ and 1.7 x 10⁹g⁻¹). Taking into consideration of quantity of spore dust production and viable spores in the spore dust, Bb5a, Ma2 and V12a were identified as potential isolates for large-scale production of dry conidial powder.

Keywords

Beauveria bassiana, Biomass, Metarhizium anisopliae, Radial Growth, Spore Production, Verticillium lecanii.

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S. Easwaramoorthy ¹, R. Nirmala ¹, G. Santhalakshmi ¹

Affiliations
1 Division of Crop Protection Sugarcane Breeding Institute Coimbatore 641 007, Tamil Nadu, IN

Abstract

Metarhizium anisopliae var. anisopliae is found on the larvae of sugarcane internode borer, Chilo sacchariphagus indicus (Kapur) under field conditions at Coimbatore. In laboratory tests, the fungus caused 20.0 to 83.3 per cent mortality in third instar larvae and 10.0 to 90.0 per cent mortality in fourth instar when treated with different doses ranging from 10⁴ to 10⁹ spores/ml. The time taken to kill the larvae varied from 5.6 to 13.1 days in third ins tar and 5.9 to 9.9 days in fourth instar. The mean number of spores produced per dead larva varied from 0.17 × 10⁹ to 0.48 × 10⁹ in third instar and 0.92 × 10⁹ to 1.52 × 10⁹ in fourth instar.

Keywords

Chilo sacchariphagus indicus, First Report, Metarhizium anisopliae, Pathogenicity.

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S. Easwaramoorthy ¹, R. Nirmala ², G. Santhalakshmi ²

Affiliations
1 Division of Crop Protection Sugarcane Breeding Institute Coimbatore 641007, Tamil Nadu, IN
2 Division of Crop Protection Sugarcane Breeding Institute Coimbatore 641007, Tamil Nadu, IN

Abstract

In a survey for natural enemies in sugarcane fields at Harinagar, West Champaran district, Bihar, the coccinellid, Micraspis univittata (Hope) was recorded for the first time in sugarcane ecosystem. The biology of the coccinellid and its predatory potential were worked out at Sugarcane Breeding Institute, Coimbatore, using the sugarcane aphid,Melanaphis sacchari (Zehnt.) as the laboratory host. The mean duration of development of M. univittata was 18.8 ± 0.6 days and the adult longevity was 37.7 ± 7.7 days. The predatory potential of grubs was 373 ± 39.6 aphids while the adults preyed on 3659.1 ± 865.9 aphids. The grubs and adults also preyed upon different stages of other sugarcane pests like shoot and internode borers. But they failed to feed on nymphs of whiteflies and eggs and nymphs of pyrilla.

Keywords

Biology,Micraspis univittata, Predatory Potential, Sugarcane Aphids.

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B. Singaravelu ¹, R. Nirmala ¹, S. Easwaramoorthy ¹

Affiliations
1 Section of Entomology, Sugarcane Breeding Institute, Coimbatore 641 007, Tamil Nadu, IN

Abstract

A granulovirus was found to infect sugarcane top borer, Scirpophaga excerptalis Walker for the first time. In a preliminary study, the virus infection in field population was found to vary from 1.6 to 14.4 (̅X = 5.8) percent. In the laboratory test, the virus caused mortality of final instar larvae up to 55.2 percent in 4 to 8 days after infection.

Keywords

Baculovirus, Granulovirus, Natural Infection, Pathogenicity, Sugarcane Top Borer.

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