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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K. V. Nayan Ganesh ¹, A. L. Reyaz ¹, N. Balakrishnan ¹

Affiliations
1 Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore – 635110, Tamil Nadu, IN

Abstract

Bacillus thuringiensis Berliner (Bt) being an eco-friendly bioinsecticide is effectively used in pest management strategies and, therefore, isolation and identification of new strains effective against a broad range of target pests is important. In the present study, four indigenous Bt isolates (T489, T491, T495 and T532) were taken and investigated for their properties such as crystal morphology, cry gene(s) content and insecticidal activity. Bipyramidal, cuboidal and spherical crystals were observed. Among the four isolates only one isolate was found positive for lepidopteran specific cry genes. The isolate T532 which showed the presence of cry1, cry2Aa and cry2Ab genes was selected for protein profiling and bioassay. The isolate showed the presence of two proteins of molecular weights at ~135 and ~65 kDa sizes. Artificial diet based bioassay resulted in 100% mortality of the neonate larvae of H. armigera and S. litura for the isolate T532 which was comparable to that of the positive control (HD1). The full length cry2A gene was amplified and cloned into E. coli DH5α strain. The recombinant plasmids were sequenced and the sequence was deposited in GenBank nucleotide database. The accession number of the gene is MH475905. The gene was named by the Bacillus thuringiensis delta endotoxin nomenclature committee as cry2Aa23.

Keywords

Bacillus Thuringiensis, Cloning, Cry2Aa, PCR.

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