Ravinder Kumar ¹, P. S. shera ², S. Sharma ², K. S. Sangha ²

Affiliations
1 Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana – 141004, Punjab, IN
2 Department of Entomology, Punjab Agricultural University, Ludhiana – 141004, Punjab, IN

Abstract

The early season attack of Chilo partellus, in kharif sown fodder maize inflicts appreciable losses, if unchecked. Biointensive management with the use of egg parasitoid Trichogramma chilonis Ishii in fodder maize through different doses and release rate was standardized. The results of the trials from two years showed that damage parameters like Leaf Injury (LI), recorded three weeks after parasitoid release from 0.25-6.00 per cent across different treatments whereas in untreated control it was 6.50-13.25 %, respectively. Similarly the observations on percent DH patterns in different treatments varied from 0.62-3.75 % as compared to control (5.50-9.0 %). Furthermore, the per cent reduction in damage was substantially low with the second inundative release of the parasitoid than plots receiving a single release of bio-agent at a given dose. The proportion of DH recorded at three weeks after release was significantly lower (1.0 and 0.62%) in plots with t-cards @ 125,000 parasitized eggs in two releases as compared with other treatments. Additionally the green fodder yield obtained in promising treatment was statistically superior (445 q ha^-1) to 392 q ha^-1 GFY as recorded in the untreated control and other lower dose treatments except the plots receiving the highest dose of parasitoid release (450q ha^-1). Thus the results suggested that field release of T. chilonis @ 125,000 parasitoids per hectare in two releases helps in substantial reduction of C. partellus inflicted damage with high economic returns.

Keywords

Chilo partellus, Deadhearts, Fodder Maize, Leaf Injury, Trichogramma chilonis.

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M. KAUR ¹, N. JOSHI ², S. SHARMA ³, A. KALIA ⁴

Affiliations
1 department of Microbiology, Punjab Agricultural University, Ludhiana - 141004, Punjab, India, IN
2 Department of Entomology, Punjab Agricultural University, Ludhiana - 141004, Punjab, India ., IN
3 Department of Entomology, Punjab Agricultural University, Ludhiana - 141004, Punjab, India, IN
4 Department of Soil Sciences, Punjab Agricultural University, Ludhiana - 141004, Punjab, India .i, IN

Abstract

The management of Spodoptera litura by entomopathogenic Nucleopolyhedrosis Viruses (NPVs) is one of the eco-friendly methods. The present study was aimed to evaluate Nucleopolyhedrosis Virus (NPV) against S. litura and its potential as a bio-pesticide. The Occlusion Bodies (OBs) of S. litura nucleopolyhedrosis virus was isolated from infected larvae collected from cabbage field. Pathogenicity studies evaluated three NPV suspensions viz. SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM against second and fourth instar larvae of S. litura recorded maximum mortality at 1×109 OBs/ml. The LC50 values of the SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM suspensions against second instar larvae were 0.584, 0.540, 0.625 OBs/mm2 , respectively, which increased to 0.696, 0.620, 0.756 OBs/mm2 against the fourth instar larvae. The LT50 at 1×109 OBs/ml was found to increase from 146.33, 137.51 and 155.88 h for SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM suspension, respectively, against the second instar larvae to 178.51, 162.07 and 187.67 h, respectively, against the fourth instar larvae. The cumulative per cent mortality, LC50 and LT50 suggested that the second instar larvae were more susceptible and easier to kill than the fourth instar larvae.

Keywords

: LC50, LT50, mortality, Nucleopolyhedrosis virus, OBs, Spodoptera litura .

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