J. Alice ¹, R. P. Sujeetha ¹, M. S. Venugopal ¹

Affiliations
1 Agricultural College and Research Institute Madurai 625 104, Tamil Nadu, IN

Abstract

Studies on the natural enemies of rice planthoppers revealed that Anagrus sp. was seen throughout the season, which shot up from the second fortnight of October to the first fortnight of Novemher. Pseudogonatopus sp. parasitized more number of Brown Planthopper (BPH). Parasitic efficiency of Pseudogonalopus sp. was more when two parasitoid adult females were released per hill. The functional response of a single mirid Cyrotorhimus lividipennis prey was greater than when in groups. A single mirid predated 3.33 and 2.66 BPH nymphs and 2.66 and 3.0 WBPH nymphs per day on TN1 and ADT36 rice varieties, respectively.

Keywords

Anagrus Sp., BPH Cyrtorhinus lividipennis Psuedogonatopus, WBPH.

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R. K. Murali Baskaran ¹, M. S. Venugopal ¹, N. R. Mahadevan ¹

Affiliations
1 Department of Agricultural Entomology, Agricultural College and Research Institute, Madurai 625 104, Tamil Nadu, IN

Abstract

Laboratory screening of twelve optical brighteners as UV protectants for Spodoptera litura (Fabricius) NPV revealed that Ranipal BVN and 2B provided excellent protection (80% original activity remaining). Effect of optical brighteners in preserving NPV was concentration dependent and an increase in concentration from 0.001 to 1.00 per cent increased the retention of viral activity from 14.8 to 99.9 per cent and 10.8 to 99.9 per cent for Ranipal BVN and 2B, respectively. Addition of selected optical brighteners, Ranipal BVN and 2B at a range of 0.001 to 1.00 per cent with S. litura NPVincreased the virulence ofNPV by reducing the LC₅₀ and LT₅₀ of NPV.

Keywords

LC₅₀, LT₅₀, Optical Brighteners, Original Activity Remaining, Spodoptera litura NPV.

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R. K. Murali Baskaran ¹, M. S. Venugopal ¹, N. R. Mahadevan ¹

Affiliations
1 Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai 625 104, Tamil Nadu, IN

Abstract

Fourth instar larvae of Spodoptera litura (Fabricius) were reared on six species of virus treated host plants and a semi-synthetic diet and observed the influence of host plants on virus induced mortality, yield of nuclear polyhedrosis virus (NPV) and virulence of resultant virus. Larvae infected through tobacco leaves recorded the highest mortality (91.7%), while it was lowest through cotton leaves (61.7%). The pH of food materials had negative relationship (r = -0.85) with mortality. However, the variation among the host food with narrow range of pH (6.9 to 8) showed that the disparity of the influence of host food on the virus induced mortality may not be only due to pH. Larvae bred through virus contaminated semi-synthetic diet yielded maximum quantity of NPV (4.207x10⁹ POBs/g of larva) which was 1.95, 1.28, 1.25, 1.13, 1.11 and 1.08 folds greater than cotton, groundnut, sunflower, tobacco and castor, respectively. LC₅₀ and LT₅₀ of NPV were also influenced by host plants and semi-synthetic diet.

Keywords

LC₅₀, LT₅₀, pH, Sl NPV.

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