POPULATION DYNAMICS OF THRIPS AND THEIR ASSOCIATION WITH BUD NECROSIS VIRUS DISEASE IN TOMATO
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Date
2020-11-19, 2020-11-19
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University of Agricultural Sciences, Bangalore
University of Agricultural Sciences, Bangalore
University of Agricultural Sciences, Bangalore
Abstract
Population dynamics studies carried out at IIHR, Bangalore during kharif and rabiseasons of 2016 and 2017 indicated that, there were three thrips species viz., Thrips palmiKarny, Scirtothrips dorsalis Hood and Frankliniella schultzie Trybom occurred together
in tomato crop. Thrips population gradually increased from vegetative to flowering and fruiting stage and gradually decreased as crop matures. The Zoophytophagous miridbug,Nesideocoris tenuis Reuter population increase was linear with thrips population. The highest mean thrips (kharif and rabi : 3.85 and 6.15/top 3 leaves) observed during 2ndweek of July (28th SMW) and 3rd week of November (47th SMW) and 23.87 per cent and 34.05 per cent of cumulative GBNV disease incidence was observed. Correlation analysis on weather parameters revealed that, during kharif highly significant negative correlation was observed between thrips and GBNV disease with rainfall (r=-0.861**and r=-0.715**). During rabi thrips and GBNV disease had highly significant negative
relationship with morning relative humidity (r=-0.742** and r=-0.711). Stepwise linearregression analysis revealed that, thrips population was highly influenced by rainfall (73%), sunshine hours (67 %), and morning relative humidity (60 %). GBNV disease was more influenced with maximum temperature (84%). Minimum temperature (71%) and rainfall (63%). Transmission studies indicated that, a single, T. palmi could able to transmit GBNV, whereas in case of S. dorsalis, two thrips adult required for minimum
GBNV transmission. Virus transmission increased with the concomitant increase ofthrips number, maximum transmission (100.00 %) achieved with 10 Thrips palmi adults per seedling and found efficient transmitter of GBNV than the Scirtothrips dorsalis
(41.67 %). Concomitant increase in feeding periods increases the virus transmission. The bioassay studies revealed that, the lowest LC50 values were recorded in spinosad andthiamethoxam and they were found to be more toxic to thrips as compared to the other insecticides tested.
Population dynamics studies carried out at IIHR, Bangalore during kharif and rabiseasons of 2016 and 2017 indicated that, there were three thrips species viz., Thrips palmiKarny, Scirtothrips dorsalis Hood and Frankliniella schultzie Trybom occurred together in tomato crop. Thrips population gradually increased from vegetative to flowering and fruiting stage and gradually decreased as crop matures. The Zoophytophagous miridbug,Nesideocoris tenuis Reuter population increase was linear with thrips population. The highest mean thrips (kharif and rabi : 3.85 and 6.15/top 3 leaves) observed during 2ndweek of July (28th SMW) and 3rd week of November (47th SMW) and 23.87 per cent and 34.05 per cent of cumulative GBNV disease incidence was observed. Correlation analysis on weather parameters revealed that, during kharif highly significant negative correlation was observed between thrips and GBNV disease with rainfall (r=-0.861**and r=-0.715**). During rabi thrips and GBNV disease had highly significant negative relationship with morning relative humidity (r=-0.742** and r=-0.711). Stepwise linearregression analysis revealed that, thrips population was highly influenced by rainfall (73%), sunshine hours (67 %), and morning relative humidity (60 %). GBNV disease was more influenced with maximum temperature (84%). Minimum temperature (71%) and rainfall (63%). Transmission studies indicated that, a single, T. palmi could able to transmit GBNV, whereas in case of S. dorsalis, two thrips adult required for minimum GBNV transmission. Virus transmission increased with the concomitant increase ofthrips number, maximum transmission (100.00 %) achieved with 10 Thrips palmi adults per seedling and found efficient transmitter of GBNV than the Scirtothrips dorsalis (41.67 %). Concomitant increase in feeding periods increases the virus transmission. The bioassay studies revealed that, the lowest LC50 values were recorded in spinosad andthiamethoxam and they were found to be more toxic to thrips as compared to the other insecticides tested.
Population dynamics studies carried out at IIHR, Bangalore during kharif and rabiseasons of 2016 and 2017 indicated that, there were three thrips species viz., Thrips palmiKarny, Scirtothrips dorsalis Hood and Frankliniella schultzie Trybom occurred together in tomato crop. Thrips population gradually increased from vegetative to flowering and fruiting stage and gradually decreased as crop matures. The Zoophytophagous miridbug,Nesideocoris tenuis Reuter population increase was linear with thrips population. The highest mean thrips (kharif and rabi : 3.85 and 6.15/top 3 leaves) observed during 2ndweek of July (28th SMW) and 3rd week of November (47th SMW) and 23.87 per cent and 34.05 per cent of cumulative GBNV disease incidence was observed. Correlation analysis on weather parameters revealed that, during kharif highly significant negative correlation was observed between thrips and GBNV disease with rainfall (r=-0.861**and r=-0.715**). During rabi thrips and GBNV disease had highly significant negative relationship with morning relative humidity (r=-0.742** and r=-0.711). Stepwise linearregression analysis revealed that, thrips population was highly influenced by rainfall (73%), sunshine hours (67 %), and morning relative humidity (60 %). GBNV disease was more influenced with maximum temperature (84%). Minimum temperature (71%) and rainfall (63%). Transmission studies indicated that, a single, T. palmi could able to transmit GBNV, whereas in case of S. dorsalis, two thrips adult required for minimum GBNV transmission. Virus transmission increased with the concomitant increase ofthrips number, maximum transmission (100.00 %) achieved with 10 Thrips palmi adults per seedling and found efficient transmitter of GBNV than the Scirtothrips dorsalis (41.67 %). Concomitant increase in feeding periods increases the virus transmission. The bioassay studies revealed that, the lowest LC50 values were recorded in spinosad andthiamethoxam and they were found to be more toxic to thrips as compared to the other insecticides tested.