Bionomics and Ecosafe Management of Major Insect Pests of Mustard
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Date
2007
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MPUAT, Udaipur
Abstract
Studies on the bionomics and eco-safe management of major insect pests of mustard were carried out at Rajasthan College of Agriculture, MPUAT, Udaipur during rabi 2004-05 and 2005-06. The appearance of mustard aphid (Lipaphis erysimi Kalt.) was observed in the second week of December (50th SMW) reaching to a peak of 196.23 aphids per 10 cm twig length per plant in the second week of February (6th SMW) during 2004-05; whereas, in 2005-06 it appeared in the first week of December (49th SMW) and the peak was observed during first week of February (5th SMW) with mean population of 87.58 aphids per twig of 10 cm length per plant. The aphid population had significant negative correlation with minimum temperature in both the years. The overall effect of relative humidity favoured the population build up of mustard aphid.
The natural enemies observed on mustard aphid included the parasitoid, Diaeretiella rapae McIntosh; and the predators, Coccinella septempunctata Linn. Cheilomenes sexmaculata Fabr., Brumoides suturalis (F.), Xanthogramma scutellarae Fabricious and Chrysoperla carnea (Stephens). The parasitization by D. rapae was recorded higher (61.22% and 74.36%) during middle of March (11th SMW) in both the years. The aphid population was significantly and positively correlated with D. rapae and the mummified aphid. Among the predators, C. septempunctata dominated and maximum population (6.65 and 4.85 grubs & beetles per plant) was observed during 7/8th SMW in both the years, respectively. The coccinellid predators, C. sexmaculata and B. suturalis had positive but poor correlation with aphid population. The peak population of X. scutellarae (1.75 and 2.10 grub per plant) was observed during 2nd /3rd week of February. A significant positive correlation existed between X. scutellarae and L. erysimi population. Similarly, C. carnea also had significant positive correlation with L. erysimi population.
The painted bug, Bagrada hilaris infestation peak (16.85 and 10.68 bugs per plant) was observed in last week of February and middle of March during two successive years. Atmospheric temperatures (maximum, minimum and mean), sunshine and evaporation rates were positively correlated with painted bug population, whereas, the painted bug was negatively correlated with relative humidity.
The sawfly infestation was maximum (2.38 and 2.33 grub/plant) at the end of November (48th and 49th SMW) during 2004-05 and 2005-06, respectively.
Studies on the biology including bionomics of mustard aphid, painted bug and mustard sawfly were conducted and have been presented.
Among the 20 varieties evaluated for their relative preference by the major insect pests, varieties Maya, Pusa agarni were most preferred by aphid and Vardan by painted bug and variety Varuna by mustard sawfly, whereas, the varieties, RH-819 was least preferred by aphid and painted bug and PBR-91 and GM-2 by sawfly. Morphological characters of different varieties of rapeseed/ mustard did not influence the level of infestation of mustard aphid. Further, varieties having compact inflorescence were preferred more than the varieties having scattered inflorescence. There was no clear cut effect of leaf colour, flower colour, stem type, and days to flowering on incidence of mustard aphid.
The insect pest infestation caused 37.22 and 33.95 per cent reduction in grain yield leading to a loss equivalent of Rs. 13,018 and Rs. 12,052 per hectare during 2004-05 and 2005-06, respectively. Besides, insect pest infestation also caused significant reduction in plant height (12.54 and10.57 %), number of primary branches (10.48and 6.65 %), secondary branches (12.04 and 10.64 %), number of siliqua per plant (38.28and 25.39 %), number of grains per siliqua (34.26 and 27.82 %), 1000-grain weight (38.34and 27.82 %) and oil content (2.81 and 2.02 %) during the respective years of investigation.
Evaluation of different treatment combinations for the management of insect pests of mustard revealed that lowest population of the aphid, painted bug and mustard sawfly was recorded on plant treated with methyl-oxy-demeton (0.025%). The treatment comprising neem seed kernel extract (5%), C. septempunctata @ 5000 grubs /ha and neem seed kernel extract (5%) was found most effective bio-intensive treatment against the aphid and painted bug. The maximum net profit of Rs. 12,652 and Rs. 12,365 with highest B: C ratio of 1.59 and 1.56 was found on methyl oxy-demeton (0.025%). during 2004-05 and 2005-06, respectively. The bio-intensive treatment comprising neem seed kernel extract (5%), C. septempunctata @ 5000 grubs /ha and neem seed kernel extract (5%) was next in order of superiority giving a net profit of Rs. 9873 and Rs. 9144/ha with respective B: C ratio of 1.44 and 1.40 during 2004-05 and 2005-06, respectively.
Description
Studies on the Bionomics and Ecosafe Management of Major Insect Pests of Mustard
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Citation
Rupawat and Rana, 2007