Compatibility of certain insecticides and fungicides, and their bioefficacy against Spodoptera litura (Fabricius)
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Date
2022-09
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G.B. Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, Uttarakhand. PIN - 263145
Abstract
A detailed investigation was undertaken to determine the physical and chemical compatibility, and bioefficacy of certain insecticides in combination with fungicides against tobacco caterpillar, Spodoptera litura (Fabricius); effect of insecticide and fungicide combinations on weight gain and feeding behaviour of S. litura; phytotoxic effects of insecticide and fungicide combinations on black gram Vigna mungo (L.) Hepper var. PU-31 of S.litura. All the experiments were conducted in Insecticide Toxicology Laboratory of the Department of Entomology.
The physical and chemical compatibility of insecticides viz. tetraniliprole, flubendiamide, novaluron + indoxacarb with fungicides viz.fluxapyroxad + pyraclostrobin, metiram + pyraclostrobin and tebuconazole + trifloxystrobin in three different types of water (tap, distilled and hard water) at room temperature (24.7 ºC) and at 35 ºC, and three different types of water (tap, distilled and hard water) in laboratory conditions. All the combinations were physically compatible as each of the insecticide and fungicide solution readily mixed without the formation of any precipitate and sediments. Regarding the chemical compatibility, the pH, Electrical Conductivity (EC) and Total dissolved solids (TDS) were stable even after 8 hours of preparation. The phytotoxic effects of three insecticides tetraniliprole, flubendiamide, novaluron + indoxacarb in combination with three fungicides fluxapyroxad + pyraclostrobin, metiram + pyraclostrobin and tebuconazole + trifloxystrobin was determined on black gram, Vigna mungo var. PU-31 at single (X) and double doses (2X). None of the combinations at recommended and double dose manifested any symptoms of phytotoxicity such as injury to leaf tip and leaf surface, wilting, vein clearing, necrosis, epinasty, and hyponasty. The results proved that all the tested treatments were phytotoxically compatible with each other. The bioefficacy of three insecticides tetraniliprole, flubendiamide, novaluron + indoxacarb in combination with three fungicides fluxapyroxad + pyraclostrobin, metiram + pyraclostrobin and tebuconazole + trifloxystrobin was determined against 4d old larvae of S. litura. [novaluron + indoxacarb] + [metiram + pyraclostrobin] resulted in maximum mortality of 86.6%, 15 days after the first spray whereas it caused 100% mortality up to 7 days after second and third spraying which reduced to 93 and 86% after 10 and 15 days of second and third spraying respectively. The least effective of all was flubendiamide in combination with tebuconazole + trifloxystrobin which resulted in minimum mortality of 20%, 15 days after the first spray, 86.6 % mortality 1 day after the second spray which reduced to 60,46,40 and 26 % at 5,7,10 and 15 days after second spraying, also 1 day after third spraying it resulted in 93.3% mortality which reduced to 66.6,53.3,50.0 and 33.3 % in 5,7,10 and 15 days respectively. The effect of three insecticides tetraniliprole, flubendiamide, novaluron + indoxacarb in combination with three fungicides fluxapyroxad + pyraclostrobin, metiram + pyraclostrobin and tebuconazole + trifloxystrobin on weight gain parameters against 4 days old S.litura was determined. At 3 days after feeding (DAF),15 days after the first spray [novaluron + indoxacarb] + [metiram + pyraclostrobin] recorded highest reduction in mean weight gain over control (78.3%). In case of 1,5 and 7 days after second and third spraying mean weight gain could not be recorded as complete mortality was observed within 48 hours. 10 days after the second spray maximum reduction in weight gain over control was observed to be 86.2% which reduced to 81.7% at 15 days after the second spray whereas, at 10 days after the third spray maximum reduction in weight gain over control was observed to be 89.5% which reduced to 73.6 % at 15 days after the third spray. This was followed by [novaluron + indoxacarb] + [fluxapyroxad + pyraclostrobin] which recorded highest mean weight gain over control (73.3%) 15 days after first spray. In case of 1 and 5 days after the second spraying mean weight gain could not be recorded as complete mortality was observed upto 48 hours. 7 days after the second spraying maximum reduction in weight gain over control was observed to be 98.9% which was reduced to 84.9 and 79.8% at 10 and 15 days after the second spraying whereas at 7 days after the third spraying maximum reduction in weight gain over control was observed to be 95.7% which reduced to 87.9 and 71.3% at 10 and 15 days after third spraying The least effective of all treatments was [flubendiamide] + [tebuconazole + trifloxystrobin] which recorded the lowest mean weight gain over control (42.2%) 15 days after the first spray. It recorded mean weight gain over control values as 96.3,81.3,73.8, 69.5, and 57.5% at 1,5,7,10, and 15 days after second spraying, and 98.6,79.4,77.7,72.3 and 46.8 % at 1,5,7,10 and 15 days after third spraying. The effect of three insecticides tetraniliprole, flubendiamide, novaluron + indoxacarb in combination with three fungicides fluxapyroxad + pyraclostrobin , metiram + pyraclostrobin and tebuconazole + trifloxystrobin on feeding behaviour of 4 day old S. litura was determined. The maximum feeding deterrence was exerted by [novaluron + indoxacarb] + [metiram + pyraclostrobin], showing minimum MLAC of 4.88 cm2 (FI=62.1%) at 15 days after first spray; MLAC value of 0.34,0.55,2.67,4.67 and 5.15 cm2 (FI=96.9,93.8,75.9,64.4 and 62.7%) at 1,5,7,10 and 15 days after second spray, respectively, and 0.06,0.35,2.44,4.16 and 5.29 cm2 (FI= 99.1, 95.8,78.4,65.8 and 59.2%) at 1,5,7,10 and 15 respectively after third spray. This was followed by [novaluron + indoxacarb] + [fluxapyroxad + pyraclostrobin] which showed minimum MLAC values of 5.55 cm2 (FI=58.0%) at 15 days after first spraying whereas in second spraying it showed minimum MLAC values of 0.48,1.21,3.18,4.93 and 5.95 (FI=95.7,87.1,72.4,63.1 and 61.5%) at 1,5,7,10 and 15 days respectively. In third spraying it recorded minimum MLAC values of 0.47,0.81,3.14,4.52 and 6.08 (FI= 88.1, 91.4,75.2,62.9 and 54.8%) at 1,5,7,10 and 15 respectively. The least effective of all was [flubendiamide] + [tebuconazole + trifloxystrobin] which showed minimum MLAC values of 15.57 cm2 (FI=13.9%) at 15 days after first spraying whereas in second spraying it showed minimum MLAC values of 1.29,5.22, 8.75,11.03 and 13.41 cm2 (FI=89.2,53.8,38.1,32.3and 30.5%) at 1,5,7,10 and 15 days respectively. In third spraying it recorded minimum MLAC values of 1.29,5.52,8.44,10.48 and 11.08 cm2 (FI= 88.1,53.6,42.6,32.4and 30.8%) at 1,5,7,10 and 15 respectively.