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S. Manimegalai ¹, N. Sathiah ¹, R. J. Rabindra ¹, G. Santharam ²

Affiliations
1 Department of Agricultural Entomology Tamil NaduAgricultural University Coimbatore 641 003, Tamil Nadu, IN
2 Department of Agricultural Entomology Tamil Nadu Agricultural University Coimbatore 641 003, Tamil Nadu, IN

Abstract

Vairimorpha necatrix (Kramer) was combined with different antibiotics to increase its pathogenicity. It was administered to third instar larvae of Spodoptera litura (Fabricius) under laboratory conditions by diet surface treatment and the mortality and spore yield was studied. Reproductive spores of V.necatrix at 10⁶ spores/ml were mixed with 100 ppm of antibiotics viz. gentamycin, oxytetracycline, ampicillin, kana mycin and chloramphenicol. The results showed that the larval mortality due to various Vairimorpha antibiotic combinations ranged from 10 to 62.07 per cent and it was high compared to prepupal and pupal stages. Assessment of spore yield in the infected larvae, pre-pupae and pupae revealed that larval stages recorded higher production of spores which ranged from 0.23 to 2.36 x 10¹⁰ spores for larva, 2.26 to 5.28 x 10⁹ spores for pre pupa and 0.28 to 2.23 x 10⁹ spores for pupa. Among the various combinations, Vairimorpha-gentamycin combination produced higher mortality and spore yield of V. necatrix.

Keywords

Antibiotics, Mortality, Spodoptera litura, Spore Yield, Vairimorpha necatrix.

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J. Rajeswaran ¹, G. Santharam ²

Affiliations
1 Department of Agricultural Entomology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore, 641003, Tamil Nadu, IN
2 TNAU, Coimbatore 641 003, IN

Abstract

The toxicity of carbosulfan was tested against eggs, larvae and adults of Chrysoperla carnea (Stephens) under laboratory conditions. Lesser ovicidal action was observed at 500 ppm (equivalent to effective field dose of 250g a. i. ha^-1). All the concentrations caused significant grub mortality when grubs were subjected to the chemical by oral feeding and thin film methods. Carbosulfan was harmful to Chrysoperla adults when assessed through contamination method.

Keywords

Carbosulfan, Chrysoperla cornea, Toxicity.

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K. Kumar ¹, G. Santharam ¹

Affiliations
1 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, IN

Abstract

In the laboratory, the safety of imidacloprid (Confidor) 200SL as foliar treatment against Trichogramma chilonis Ishii and Chrysoperla carnea (Stephens) was evaluated. The results revealed that there was no significant adverse effect on adult emergence and percent parasitisation of T. chilonis and percent hatchability of Chrysoperla carnea. There was a significant adverse effect on C. carnea grubs and adult longevity when they were fed with imidacloprid. These adverse effects can be overcome by adopting seed treatment.

Keywords

Chrysoperla carnea, Imidacloprid, Safety, Trichogramma chilonis.

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G. Santharam ¹, D. Rose Victoria ¹, R. J. Rabindra ¹, S. Jayaraj ¹

Affiliations
1 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore - 641 003, IN

Abstract

Helicoverpa (= Heliothis) armigera (Hubner) is a serious pest of chickpea (Cicer arietinum L.) in most parts of India. The larvae infest the crop almost throughout its growth phase, being low at the vegetative and flowering stages and high at the grain development stage (Yadava and Lal, 1988). In the state of Tamil Nadu, the loss caused by H.armigera to chickpea was 40 per cent in 1987-88 (Jayaraj, 1990). Rawat et al. (1979) reported 50-100 per cent loss in yield under field conditions. Several attempts have been made in the past to control the pest with chemical insecticides and also microbials. In . the present study, an attempt was made to assess the efficacy. of microbials, Bacillus thuringiensis and nuclear polyhedrosis virus (NPV) of H.armigera and a chemical insecticide, endosulfan and their combinations.

Keywords

Microbial Control, Helicoverpa armigera, Chickpea, Bacillus thuringiensis var., kurstaki, Endosulfan, Nuclear Polyhedrosis Virus.

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G. Santharam ¹, S. Jayaraj ¹

Affiliations
1 Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641 003, IN

Abstract

The transmission of a nuclear polyhedrosis virus (NPV) from generation to generation was studied in Spodoptera litura (F.). NPV-infected adults were produced by feeding 5th instar larvae with sub-normal concentration of NPV. Egg and larval mortality was observed in the progeny from infected adults, the transmission being transovum and transovarial. The healthy adults were able to transmit the NPV to their progeny by egg surface coating when fed with NPV orally, more so when both the sexes were fed. The larval mortality was more in the case of eggs laid on the first day and declined in the case of second and third day laid eggs.

Keywords

Spodoptera litura, Nuclear Polyhedrosis Virus, Transmission, Transovum, Transovarial.

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K. Kumar ¹, G. Santharam ²

Affiliations
1 Department of Entomology, Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal, Puducherry (U.T.), IN
2 Department of Entomology, TamilNadu Agricultural University, Coimbatore (T.N.), IN

Abstract

Chemical insecticides have been the backbone of insect pest control since the early 1950’s when organochlorine insecticides were first widely introduced. Indiscriminate use of the chemical insecticides which are active against a broad spectrum of insects led to many ecological problems. Chemicals are to be used judiciously which serve as a major tool in pest management.

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K. Kumar ¹, G. Santharam ², R. Sridhar ³

Affiliations
1 Department. of Agricultural Entomology, P.J.N.College of Agriculture and Research Institute, Karaikal (Puducherry), IN
2 Department of Entomology, TamilNadu Agricultural University, Coimbatore ( T. N.), IN
3 Department of Microbiology, TamilNadu Agricultural University, Coimbatore ( T.S N.), IN

Abstract

In cotton, the compatibility of imidacloprid as seed treatment was evaluated with plant pathogenic antagonistic microorganisms, Trichoderma viride (Pers) and Pseudomonas fluorescens (Migula). The radial growth of T. viride was less at higher concentration of 7000 ppm (12.5mm) compared to the untreated check (15.1mm) at 24 h. The radial growth was less in treatments compared to untreated check at 48 and 72 h of incubation. Similarly the spore yield was less in treatments compared to untreated check. Regarding the bioefficacy of T. viride, the radial growth of the pathogen, Macrophomina phaseolina was 20 mm in the treatment of T. viride alone while it was 38 and 40 mm in the combination treatments of imidacloprid 70 WS at 7 g and 5 g kg-1 with T. viride 4 g kg-1while in the untreated check it was 45 mm. In the pot culture studies, it was found that the population of T. viride was higher in the treatment of T. viride 4 g kg-1alone compared to the combination treatment of imidacloprid 70 WS and T. viride. Similar trend was also observed in case of P. fluorescens. It was concluded that imidacloprid was having lesser impact on T. viride and significant inhibitory effect on P. fluorescens.

Keywords

Cotton, Trichoderma viride, Pseudomonas fluorescens, Imidacloprid.

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