Abstract

            The relative screening of 15 germplasm and 10 varieties of mustard under field as well as in net house conditions, environmental effects on population and safer insecticidal management of mustard sawfly, Athalia proxima Klug and mustard aphid, Lipaphis erysimi Kalt. were conducted at Student's Instructional Farm and Insectary of the Department of Entomology, C. S. Azad University of Agriculture & Technology, Kanpur during two consecutive years 2004-05 and 2005-06.

            Incidence of sawfly was observed at early seedling stage in the 2^nd week of November and peaked at 4^th week of November (18.00-27.66 larvae/10 plants) when the crop age was 22 - 29 days, temperature 28.6-28.6^oC maximum and 9.7-13.8^oC minimum along with R.H. 91.6 - 82.9 per cent in morning and 53.0 - 28.0 per cent in evening hours of the day during 2004-05 and 2005-06, respectively. The maximum and minimum temperature had significant positive correlation, while relative humidity showed non-significant negative impact with the larval population of A. proxima.

            The aphid population was appeared in the flowering stage at the end of December to 2^nd week of January, whereas its population was peaked (292 - 348.7 aphid/10 cm of twig) in 2^nd-3^rd week of February when the concerning temperature was 24.7 - 24.8^oC maximum, and 10.6 - 10.6^oC minimum along with R.H. 83.6 - 94.7 per cent in morning and 40.0 - 67.3 per cent in evening hours of the day during 2004 - 05 and 2005 - 06, respectively. The temperature (minimum and maximum), relative humidity (morning and evening) and rainfall all had non-significant positive correlation with aphid population.

            The mustard germplasm/varieties RK 2010, RK 2015, Kanti, Urvasi and RK 2014 were the most superior which registered lesser, population of sawfly larval 9.67, 13.67/10 plants. Whereas, RK 2001, RK 2006, Kesari and Basanti was inferior which suffered with increased population of sawfly larvae 29.33-26.00/10 plants.

            Ovipositional preference of female sawfly in net house was less (7.67-8.00 egg/5 plants) on RK 2010, RK 2015, Kanti, Urvasi, RK 2011 and RK 2004 during both the years. Whereas RK 2006, Rohini, RK 2013, Basanti, Kesari and Varuna were most preferred (25.00 to 19.33 eggs/5 plants). The egg hatchability was lower on RK 2011, RK 2010, RK 2004, Kanti, RK 2014, RK 2015, PR 4001 and Urvasi (75.46-82.20%). Whereas, RK 2006, Varuna, Maya and RK 2003 were most suited for egg hatching (97.00-94.17%). After two weeks of sawfly adult release in the net house the lower larval population 4.52-8.00/5 plants was registered on RK 2010, RK 2015, Kanti, Urvasi, RK 2004, RK 2011, RK 2014 and RK 2003. However, higher larval population 15.00 to 11.00/5 plants were found on RK 2006, Rohini, RK 2013, Basanti and RK 2001. The per cent leaf damage caused by these larvae was lowest (21.00 to 28.33%) on RK 2010, RK 2015, Kanti, RK 2014 and Urvasi which were categorised as moderately resistant. RK 2004 and RK 2011 were found to be moderately susceptible against A. proxima (28.33 - 36.23%).  

            The lesser aphid population under field conditions was observed on       RK 2014, Vardan, Kesari, RK 2009 and RK 2002 which was varied from 152.7 to 250.7 aphid/10 cm of twig being most superior against aphid during both the years. Whereas its higher intensity 272.2 to 430.8 aphid/10 cm of twig were recorded on RK 2011, RK 2012, RK 2007, Varuna and Maya. On the basis of aphid infestation index the germplasm/varieties of mustard RK 2014, Kesari, Vardan, Rohini, RK 2009, RK 2002, Basanti, Kanti and RK 2003 were categorized as moderately resistant, whereas, other germplasm/varieties were susceptible to aphid attack. The aphid multiplication under net house condition was lowest on RK 2014, Kesari, Vardan, RK 2009 and Rohini varied from 8.24 to 16.81 and were least suitable for aphid. Whereas increased multiplication was recorded on RK 2011, RK 2012, Varuna and RK 2007.

            Among eight insecticides tested against mustard sawfly; acetamiprid, dimethoate, imidacloprid and novaluron were best which reduced the larval population over control up to 80.11-83.78, 72.12-76.28, 72.28-74.86 (after   7days) and 72.69-74.32 per cent (after 3 days) during both the years, respectively. Endosulfan, neemarin and NSKE were found as moderately effective, whereas B. bassiana was not effective against larvae of sawfly under field conditions. Efficacy of acetamiprid, dimethoate and imidacloprid was higher against L. erysimi in field conditions. These treatments reduced the aphid population over control up to 90.22-92.80, 87.37-90.07 and 85.73-86.97 per cent for 7 days of 1^st spraying and 91.66-92.31, 88.73-88.71 and 84.90-83.96 per cent for 14 days of 2^nd spraying, during the years, respectively. Novaluron and endosulfan achieved the moderate level of control 80.7-76.67 and 78.92-76.30 per cent after 3 days of 1^st spraying and 70.24-74.13 and 69.62-74.36 per cent for 3 days of 2^nd spraying, respectively. Neemarin and NSKE were also found effective after endosulfan whereas B. bassiana was least effective for the control of aphid. The mustard crop treated with acetamiprid, dimethoate and imidacloprid produced increased grain yield up to 47.20-48.04, 45.02-46.08 and 42.38-44.44 per cent over control, respectively. Novaluron and endosulfan produced moderate grain yield, whereas, B. bassiana, neemarin and NSKE were less effective to increase the grain yield sufficiently.

Key words:  Germplasm, screening, Brassica, Athalia proxima, Lipaphis erysimi, population fluctuation, temperature, relative humidity, rainfall, management, insecticides, efficacy.

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