Bio-efficacy of Biopesticides Evaluated against Corn Leaf Aphid, Rhopalosiphum maidis (Fitch) Infesting Maize

Abstract

Introduction: Maize (Zea mays L.), is a member of the Poaceae family. After rice and wheat, it is the third-most significant cereal in India, making up around 9% of the country's total food consumption. Aims: For effective and eco-friendly pest management approach against maize aphid is the necessity of present time to safeguard the natural enemies and pollinators as well as human health. Study design:  Randomized block design Place and Duration of Study: Entomology farm, Anand Agricultural University, Anand during rabi 2021-22 Methodology: Field experiment was carried out in an area of 4.8×6.0 m2 on maize var GAYMH-3. There were in all eight treatments including untreated control plots and each treatment were replicated thrice. The first spray of respective bio-pesticides was given at the time of occurrence of aphid and second spray was applied after 15 days of first spray. Number of nymphs/adults were recorded from centre of shoot, inflorescence (tassel) and cob of randomly selected ten plants from each plot before spray and 1,3, 7 and 10 day(s) after first and second spray applications. Results: Among the seven biopesticides studied against corn leaf aphid, on tassel Lecanicillium lecanii 1.15% WP conclude most effective followed by Metarhizium anisopliae 1.15% WP and Beauveria bassiana 5% WP and similarly, on cob L. lecanii 1.15% WP found most effective followed by M. anisopliae 1.15% WP and B. bassiana 5% WP. Further, Plot treated with L. lecanii 1.15% WP, M. anisopliae 1.15% WP and B. bassiana 5% WP gave highest grain yield   5523, 5503, 5462 kg/ha, green fodder yield 7491, 7443 and 7244 kg/ha, dry fodder yield 5977, 5921 and 5705 kg/ha, respectively. For natural enemies; neem oil 1% and neem seed kernel extract 5% found less toxic compared to other treated bio-pesticides to LBB adults on tassel and on cob. Looking to grub, neem seed kernel extract 5%, azadirachtin 0.15% EC and garlic bulb extract 5% noticed less toxic to grubs on tassel and cob. Conclusion: Among the tested biopesticides on aphids the best result in controlling the aphid population were obtained with the treatment of L. lecanii, M. anisopliae and B. bassiana.