EVALUATION OF PHEROMONE BLENDS AND BIORATIONAL INSECTICIDES FOR THE MANAGEMENT OF Spodoptera frugiperda (J. E. Smith) (Lepidoptera : Noctuidae) IN MAIZE
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Date
2023-12-01
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Acharya N G Ranga Agricultural University
Abstract
Studies on ‘Evaluation of Pheromone Blends and Biorational Insecticides for the Management of Spodoptera frugiperda (J. E. Smith) (Lepidoptera : Noctuidae) in Maize’ were conducted at Regional Agricultural Research Station (RARS), Lam, Guntur during four seasons i.e., kharif 2019, rabi 2019-20, kharif 2020 and rabi 2020-21 with an aim to study the survey on the incidence of S. frugiperda in Guntur, Krishna and Prakasam districts of Andhra Pradesh, evaluation of pheromone blends against fall armyworm, assessment of damage potentials of fall armyworm at different crop growth stages and evaluation of bio-rational insecticides against fall armyworm.
Highest per cent leaf damage was observed in Prakasam district with 21.91per cent during kharif 2019 and lowest per cent (6.87%) of leaf damage was observed in Guntur district during rabi 2020-21. Among three crop growth stages reproductive stage recorded highest per cent leaf damage of 24.29 per cent during kharif 2019 and lowest per cent leaf damage of 3.47 per cent was recorded in reproductive stage during during rabi 2020-21.
Study on evaluation of pheromone blends against S. frugiperda in maize during kharif 2019 and 2020 demonstrated that among the seven different pheromone blends, Z9-14Ac:Z11-16Ac:Z7-12Ac (85.5:12.5:2) pheromone blend was found to be most effective blend which attracted highest number of moths at 98 DAS (50.00 moths/trap/week) and lowest number of moth catches at 49 DAS (7.17 moths/trap/week). Z9-14Ac:Z11-16Ac (99.4:0.6) blend was next best effective blend which attracted more number of moths at 98 DAS (39.67 moths/trap/week) and least number of moth catches was observed at 49 DAS (1.83 moths/trap/week). Z9-14Ac:Z11-16Ac (87:12.5:0.5) pheromone blend attracted more number of moths (15.33 moths/trap/week) at 77 DAS and lowest at 7 DAS (1.00 moths/trap/week). Whereas, Z9-14Ac:Z11-16Ac:Z7-12Ac (10:1:0.1) and Z9-14Ac:Z11-16Ac:Z7-12Ac
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(10:1.5:0.1) attracted more number of moths (8.50 and 5.84 moths/trap/week) at 63 and 35 DAS respectively. Similar results were obtained during rabi 2019-20 and 2020-21 also.
Assessment of damage potentials of S. frugiperda at different crop growth stages during kharif 2019, 2020 and rabi 2019-20, 2020-21 indicate that completely protected plot was recorded with 8.08 to 14.73 per cent leaf damage with 0.50 to 1.30 damage scale and achieved 68.24 to 70.45 q ha-1 yield. Completely unprotected plot recorded 100 per cent leaf damage at 42 DAS with 9.00 damage scale and achieved 10.97 to 13.66 q ha-1 yield.
Completely protected plot recorded 57.27 and 56.79 q ha-1 incremental yield compared to unprotected plot in kharif and rabi seasons respectively with 9.02 and 6.07 per cent yield loss. In 60 days protected plot recorded 49.12 and 50.28 q ha-1 incremental yield and 18.34 and 16.30 per cent yield loss respectively compared to unprotected plot. In 40 days protected plot with management practices up to 42 DAS, 29.69 and 31.87 q ha-1 incremental yield was noted as compared to unprotected plot, with 45.79 and 49.30 per cent yield loss respectively. Whereas, unprotected plot had received 10.97 and 13.66 q ha-1 incremental yield with 85.38 and 81.79 per cent yield loss compared to fully protected plot.
Among the seven treatments tested, the lowest per cent of leaf damage was observed in spinosad 45% SC treatment by 21.50 per cent (0.06 larvae/plant) at 3 DAT, which is statistically on par with emamectin benzoate 5% SG (23.39% and 0.09 larvae/plant) and novaluron 10% EC (28.79% and 0.11 larvae/plant). The remaining treatments i.e azadirachtin 1500 ppm, NSKE 5%, Bacillus thuringiensis (Berliner) and Metarhizium rileyi (Farlow) had recorded 43.30, 45.73, 49.38, 50.98 per cent leaf damage and 0.25, 0.30, 0.36, 0.48 larvae/plant respectively. Similar trend was observed at 7 and 10 DAT. Similar trend of per cent leaf damage and larval population was also observed in rabi 2019-20 and 2020-21. During rabi season M. rileyi was performed better compared to B. thuringiensis.
Spinosad 45% SC (92.41%) and emamectin benzoate 5% SG (89.96%) were found effective in reducing the larval population over control, they were followed by novaluron 10% EC (85.46%). Lowest per cent population reduction over control was observed in B. thuringiensis (55.19%) and M. rileyi (43.98%) treatments and were statistically at par with one another. Similar trend was observed at 7 and 10 DAT. Similar trend of per cent population reduction over control was observed in rabi 2019-20 and 2020-21 also, but in rabi season M. rileyi was performed better compared to B. thuringiensis.
Regarding yields highest kernel yields of 67.50 and 76.40 q ha-1 was obtained from plots treated with spinosad 45% SC in kharif and rabi seasons respectively. Emamectin benzoate 5% SG and novaluron 10% EC which were on par with spinosad 45% SC recorded the yields of 65.04, 73.77 and 59.70, 69.38 q ha-1 respectively. Azadirachtin 1500 ppm, NSKE 5%, B. thuringiensis and M. rileyi were on par and recorded the yields of 50.33, 47.11, 36.71, 30.70 and 62.18, 55.63, 45.19, 49.20 q ha-1 respectively in kharif and rabi seasons. Control plot recorded lowest yields of 27.65 and 35.24 q ha-1 in kharif and rabi seasons respectively.