N. Balakrishnan ¹, R. K. Murali Baskaran ², N. R. Mahadevan ²

Affiliations
1 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, IN
2 Department of Agricultural Entomology, Agricultural College and Research Institute (TNAU), Madurai 625 104, Tamil Nadu, IN

Abstract

A study was undertaken to observe the combined effects of Trichogramma chilonis with some biopesticides viz., HaNPV, Bacillus thuringiensis var. kurstaki (HaIt WP) and Beauveria bassiana (Bev Bas). Two releases of T. chilonis with two sprays of B.t.k. recorded less mean larval popUlation (O.33/plant). less damage on shed squares (42.78%), intact squares (9.12%), bolls (14.20%) and loculi (10.68%) and recorded higher yield (782 kg/ha). Two releases of T. chilonis with two sprays of HaNPV was the next best treatment regarding less mean larval popUlation and damage on fruiting parts. Application of B. bassiana alone and in conjunction with T. chilonis proved less effective compared to other treatments. Two releases of T. chilonis with one spray of B.t.k or HaNPV and T. chilonis alone performed moderately in reducing the larval population and damage on fruiting parts.

Keywords

Biopesticides, Efficacy, Helicoverpa armigera, Trichogramma chilonis.

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N. Balakrishnan ¹, R. K. Murali Baskaran ², N. R. Mahadevan ²

Affiliations
1 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu, IN
2 Department of Agricultural Entomology, Agricultural College and Research Institute (TNAU), Madurai 625 104, Tamil Nadu, IN

Abstract

The present investigation was carried out to study the field efficacy of Chrysoperla carnea (Stephens) in combination with biopesticides against Helicoverpa armigera (Hiibner). The lowest mean larval population of H. armigera, minimum damage on shed squares, squares (intact), bolls and loculi and higher yield were recorded in two releases of C. carnea and two sprays of Bacillus thuringiensis var. kurstaki (B.t.k.) treated plots followed by C. cornea in conjunction with HaNPV and B.t.k alone treated plots. The field recovery of C. cornea, HaNPV infected, Bacillus thuringiensis var. kurstaki infected and Beauveria bassiana mycosed larvae was more in their respective alone treated plots. The incremental cost benefit ratio was obtained maximum in chlorpyriphos 20 EC alone (1: 3.66) followed by HaNPV alone (1: 3.S(), two releases of C. carnea with two sprays of HaNPV (1: 2.88) and two releases of C. carnea with one spray of HaNPV (1: 2.48).

Keywords

Biopeslicides, Chrysoperia carnea, Cotton, Helicoverpa armigera, ICBR.

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V. R. Swaminathan ¹, R. K. Murali Baskaran ¹, N. R. Mahadevan ¹

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

Abstract

Among six intercrops evaluated, cotton (Gossypium hirsutum L.) intercropped with sunflower and cowpea in paired row system were favourable for the conservation of Chrysoperla carnea (Stephens), Cotton alone was comparatively less favourable to the multiplication of C. carnea, which correspondingly recorded more population of insect pests. The population of C. carnea did not show any influence on the population of Amrasca devastans Ishida.

Keywords

Chrysoperla carnea, Helicoverpa armigera, Intercropping System, Sucking Pests.

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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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