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In the year 1993, a 100 tree plot in a 17 year old teak plantation at Nilambur in Kerala was experimentally protected from Hyblaea puera Cramer, a serious defoliator of teak plantations, using a naturally occurring baculovirus (HpNPV) reported earlier from this pecies. During the year, there were four major peaks of defoliator infestation from March to June. One-time foliar application of a crude preparation of HpNPV at the rate of 1x105 POB/ml of the spray fluid, at the earliest sign of each infestation, gave 70-76 per cent protection of foliage during the first two infestations. A reduced foliage protection of 33-43 per cent obtained during the third and fourth infestations was attributable to occurrence of rain soon after application of the spray. In protected trees, the basal area increment was enhanced by 41 per cent, indicating the efficacy of HpNPV as a biocontrol agent against the teak defoliator.

In the year 1993, a 100 tree plot in a 17 year old teak plantation at Nilambur in Kerala was experimentally protected from Hyblaea puera Cramer, a serious defoliator of teak plantations, using a naturally occurring baculovirus (HpNPV) reported earlier from this pecies. During the year, there were four major peaks of defoliator infestation from March to June. One-time foliar application of a crude preparation of HpNPV at the rate of 1x105 POB/ml of the spray fluid, at the earliest sign of each infestation, gave 70-76 per cent protection of foliage during the first two infestations. A reduced foliage protection of 33-43 per cent obtained during the third and fourth infestations was attributable to occurrence of rain soon after application of the spray. In protected trees, the basal area increment was enhanced by 41 per cent, indicating the efficacy of HpNPV as a biocontrol agent against the teak defoliator.

The nucleopolyhedrovirus of the teak defoliator, Hyblaea puera Cramer (Lepidoptera: Hyblaeidae) (HpNPV) is a potential biocontrol agent of the pest. This paper describes a method to mass multiply HpNPV in situ in the field population of H. puera. The method is based on application of the virus suspension on young teak plantation infested with H. puera. An average yield of 4.8816 x 10& Polyhedral Occlusion Bodies (POBs) per fifth instar larva was obtained with this method. The advantage of this method of HpNPV production is that it is less expensive as it does not depend on host larval culture maintained in the laboratory.

Surveys for entomopathogenic fungi in the central forest circle of Kerala revealed the seasonal incidence of Beauveria bassiana in small pockets on Gargara mixta Buckton (Hemiptera: Membracidae) feeding on the leaves of Helicteres isora (Sterculiaceae) in the moist deciduous forests (MDF) at Vazhachal. Incidence of B. brongniartii on chrysomelid beetles (Coleoptera) feeding on teak leaves was also observed in small pockets in teak plantations. Infection was prevalent during post-monsoon months. The infection due to B. bassiana and B. brongniartii ranged from 36.8 to 100 and 45.5 to 100 per cent, respectively. The seasonal incidence of naturally occurring entomofungal pathogens, B. bassiana and B. brongniartii form small scale epizootics in nature under favourable environmental conditions. Such virulent pathogens can be exploited in pest control programmes.

The nucleopolyhedrovirus of the teak defoliator, Hyblaea puera Cramer (Lepidoptera: Hyblaeidae) (HpNPV) is a potential biocontrol agent of the pest. This paper describes a method to mass multiply HpNPV in situ in the field population of H. puera. The method is based on application of the virus suspension on young teak plantation infested with H. puera. An average yield of 4.8816 x 10& Polyhedral Occlusion Bodies (POBs) per fifth instar larva was obtained with this method. The advantage of this method of HpNPV production is that it is less expensive as it does not depend on host larval culture maintained in the laboratory.

Surveys for entomopathogenic fungi in the central forest circle of Kerala revealed the seasonal incidence of Beauveria bassiana in small pockets on Gargara mixta Buckton (Hemiptera: Membracidae) feeding on the leaves of Helicteres isora (Sterculiaceae) in the moist deciduous forests (MDF) at Vazhachal. Incidence of B. brongniartii on chrysomelid beetles (Coleoptera) feeding on teak leaves was also observed in small pockets in teak plantations. Infection was prevalent during post-monsoon months. The infection due to B. bassiana and B. brongniartii ranged from 36.8 to 100 and 45.5 to 100 per cent, respectively. The seasonal incidence of naturally occurring entomofungal pathogens, B. bassiana and B. brongniartii form small scale epizootics in nature under favourable environmental conditions. Such virulent pathogens can be exploited in pest control programmes.

Effect of four entomopathogenic fungi, Beauveria bassiana, B. brongniartii, Paecilomyces fumosoroseus and Metarhizium anisopliae, isolated from different host insects, was tested in the laboratory against the teak defoliator, Hyblaea puera (Cramer) (Lepidoptera: Hyblaeidae) to assess their virulence and efficiency. Five different concentrations, 2x106, 4x106, 6x106, 8x106 and 1x107 conidia ml-1were directly and indirectly applied onto third instar larvae of H. puera. All the four fungi tested under both application methods were pathogenic to H. puera with higher efficiency in direct application than indirect application. At 9 days after exposure, the mean per cent mortality obtained was 100, 93.02, 93.02 and 66.74%, respectively, for B. bassiana, B. brongniartii, P. fumosoroseus and M. anisopliae at the highest concentration of 1 x 107 conidia ml-1 in direct application. Mortality of the larvae varied according to the concentration of conidia, method of application and fungi. The lowest LC50 (1.89 x 106 conidia ml-1) and LT50 (91.18 hr) values obtained for B. bassiana in direct application showed that B. bassiana was more pathogenic to H. puera than the other three fungi.

Effect of four entomopathogenic fungi, Beauveria bassiana, B. brongniartii, Paecilomyces fumosoroseus and Metarhizium anisopliae, isolated from different host insects, was tested in the laboratory against the teak defoliator, Hyblaea puera (Cramer) (Lepidoptera: Hyblaeidae) to assess their virulence and efficiency. Five different concentrations, 2x106, 4x106, 6x106, 8x106 and 1x107 conidia ml-1were directly and indirectly applied onto third instar larvae of H. puera. All the four fungi tested under both application methods were pathogenic to H. puera with higher efficiency in direct application than indirect application. At 9 days after exposure, the mean per cent mortality obtained was 100, 93.02, 93.02 and 66.74%, respectively, for B. bassiana, B. brongniartii, P. fumosoroseus and M. anisopliae at the highest concentration of 1 x 107 conidia ml-1 in direct application. Mortality of the larvae varied according to the concentration of conidia, method of application and fungi. The lowest LC50 (1.89 x 106 conidia ml-1) and LT50 (91.18 hr) values obtained for B. bassiana in direct application showed that B. bassiana was more pathogenic to H. puera than the other three fungi.

The economics of mass production of the nucleopolyhedrovirus of the teak defoliator, Hyblaea puera Cramer (Lepidoptera: Hyblaeidae) (HpNPV) using the laboratory-reared and field-collected (from teak plantations) host larvae was compared. The data were based on 7645 laboratory-reared (LR) larvae and 8925 field-collected (FC) larvae. The virus production was carried out using fifth instar larva inoculated with 1x106 OBs (Viral Occlusion Bodies)/larva. The virus yield/larva in LR and FC larvae was 4.8x108 and 3.6x108 OBs, respectively. The virus productivity ratio in LR and FC larvae was 241 ± 55 and 178 ± 100.85 OBs, respectively. The cost of production of HpNPV per larva was higher in the case of LR (Rs. 0.82/larva) in comparison with FC (Rs.0.72). However, the cost of HpNPV required for spraying in one hectare at the rate of 1.63 x 1011 OBs worked out to be Rs. 279 and Rs. 317 in the case of LR and FC, respectively. A marginal difference in the virus yield was found affecting the cost of the virus produced.

The bark eating caterpillar, Indarbela quadrinotata Walker is a serious pest of Casuarina equisetifolia in Tamil Nadu State. Survey conducted in plantations located in different parts of the State resulted in detection of a potential strain of the biocontrol agent, Beauveria bassiana. Laboratory evaluation of B. bassiana against l. quadrinotata revealed that the fungal suspension at concentrations of 2 x 106, 2 x 107 and 2 x 108 spores/ml was able to kill 66.67 per cent larvae. The fungus at a concentration of 4 x 108 spores/ml gave 100 per cent mortality of the test larvae. The LC50 at 240 hours was 1.6 x 106 spores/ml and the LT50 for the most effective concentration was 82.86 hours.

The bark eating caterpillar, Indarbela quadrinotata Walker is a serious pest of Casuarina equisetifolia in Tamil Nadu State. Survey conducted in plantations located in different parts of the State resulted in detection of a potential strain of the biocontrol agent, Beauveria bassiana. Laboratory evaluation of B. bassiana against l. quadrinotata revealed that the fungal suspension at concentrations of 2 x 106, 2 x 107 and 2 x 108 spores/ml was able to kill 66.67 per cent larvae. The fungus at a concentration of 4 x 108 spores/ml gave 100 per cent mortality of the test larvae. The LC50 at 240 hours was 1.6 x 106 spores/ml and the LT50 for the most effective concentration was 82.86 hours.

The economics of mass production of the nucleopolyhedrovirus of the teak defoliator, Hyblaea puera Cramer (Lepidoptera: Hyblaeidae) (HpNPV) using the laboratory-reared and field-collected (from teak plantations) host larvae was compared. The data were based on 7645 laboratory-reared (LR) larvae and 8925 field-collected (FC) larvae. The virus production was carried out using fifth instar larva inoculated with 1x106 OBs (Viral Occlusion Bodies)/larva. The virus yield/larva in LR and FC larvae was 4.8x108 and 3.6x108 OBs, respectively. The virus productivity ratio in LR and FC larvae was 241 ± 55 and 178 ± 100.85 OBs, respectively. The cost of production of HpNPV per larva was higher in the case of LR (Rs. 0.82/larva) in comparison with FC (Rs.0.72). However, the cost of HpNPV required for spraying in one hectare at the rate of 1.63 x 1011 OBs worked out to be Rs. 279 and Rs. 317 in the case of LR and FC, respectively. A marginal difference in the virus yield was found affecting the cost of the virus produced.

Infectivity of the soil mixed conidia of the fungal pathogen Metarhizium anisopliae var. major was evaluated against the termite, Odontotermes guptai Roonwal and Bose under laboratory conditions. Four concentrations, viz., 0.8x107, 1.2x107, 1.6x107 , and 2x10

Infectivity of the soil mixed conidia of the fungal pathogen Metarhizium anisopliae var. major was evaluated against the termite, Odontotermes guptai Roonwal and Bose under laboratory conditions. Four concentrations, viz., 0.8x107, 1.2x107, 1.6x107 , and 2x10

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