Population dynamics of Pyrilla perpusilla, Walker, its bioagents on sugarcane and bio-efficacy of some insecticides against them
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Date
2016
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Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)
Abstract
Field experiments were carried out during the crop season of 2015-16 with sugarcane variety BO-153 at Sugarcane Research Farm, S.R.I., Pusa to study the Population dynamics of Pyrilla perpusilla, Walker, its bioagents on sugarcane and bio-efficacy of some insecticides against them.
The absolute population of egg masses recorded its peak (7.0 egg masses/10 leaves) was observed in the first fortnight of June 2015, when corresponding weather parameters viz; temperature oC (max. and Min.), RH(%) at 07 hrs and 14 hrs and rainfall (mm) were 38.20C, 25.50C, 83%, 44% and 19.8 mm, respectively to the crop. Correlation was found that temperature, (maximum and minimum) showed highly significant positive correlation with population (egg masses) of the insect. While relative humidity recorded (07 hrs) significant correlation but statistically was found as negative relationship. However, rainfall exhibited positive relation but statistically was non significant.
The absolute population of nymphs ranged from 0.1 to 45.5 per 10 leaves, and reached its peak (45.5 nymphs/10 leaves) was observed in the first fortnight of June, 2015, when corresponding weather parameters viz; maximum, minimum temperature (oC), relative humidity (%) at 07 hrs and 14 hrs and rainfall (mm) were 38.20C, 25.50C, 83%, 44% and 19.8 mm, respectively. Correlation was found that temperature, (maximum and minimum) showed highly significant positive correlation with population (nymphs) of the insect. While relative humidity recorded (07 hrs and 14 hrs) significant correlation but statistically was found as negative relationship. However, rainfall exhibited positive and found statistically was non significant.
The absolute population of adults recorded its peak (35.2 adults/10 leaves) in the second fortnight of May 2015, when corresponding weather parameters viz; maximum, minimum temperature (oC), relative humidity (%) at 07 hrs and 14 hrs and rainfall (mm) were 36.4oC, 24.1oC, 81%, 48% and 28.6 mm, respectively. Correlation was found that temperature, (maximum and minimum) showed highly significant positive correlation with adults population of the insect. While relative humidity recorded at 07 hrs showed significant negative correlation but statistically was found as negative relationship. However rainfall exhibited positive correlation and found yet significant correlation.
The absolute population of cocoons ranged from 0.10 to 3.7 per ten leaves and reached its peak in the 2nd fortnight of August 2015, (3.7 cocoon/10 leaves)), when the maximum and minimum temperature (0C) were from 33.10C and 24.30C with relative humidity (%) 07 hrs and 14 hrs were 92% and 75% and rainfall 400.4 mm. Correlation was found that minimum temperature with relative humidity (07 hrs and 14 hrs) and rainfall showed highly significant positive correlation with population (cocoons) of the parasitoid. While maximum temperature, showed non significant correlation but statistically was found as positive relationship.
The maximum (61.4%) parasitization by Epiricania melanoleuca on pyrilla during second fortnight of August, 2015 when, corresponding weather parameters i.e., temperature (0C) maximum, minimum, relative humidity (%) at 07 and 14 hrs and rainfall (mm) were 33.10C, 24.30C, 92%, 7%5 and 400.4 mm, respectively. On the other hand minimum (0.2%) parasitization was recorded during first fortnight of November, 2015. Correlation was found that minimum temperature, relative humidity (07 hrs) and rainfall, showed highly significant positive relation with parasitization of P. Perpusilla while, maximum temperature was showed positive correlation but statistically non significant with parasitization.
The parasitization of pyrilla eggs by Tetrastichus pyrillae and reaching its peak 100 per cent in October to first fortnight of November 2015, thereafter parasitization was observed declined trend. The effect of the weather parameters is concerned, the maximum (100%) parasitization during October to first fortnight of November was recorded with corresponding weather parameters i.e., temperature (0C) maximum, minimum, relative humidity (%) at 07 hrs and 14 hrs and rainfall (mm) were 30.40C, 15.40C, 90%, 48% and untraceable, respectively. Correlation was found that minimum temperature, relative humidity 07 hrs, showed significant positive correlation with parasitization of pyrilla while, maximum temperature, relative humidity 14 hrs and rainfall were showed non significant positive correlation with parasitization.
The data regarding the treatments along with their mean per cent mortality of pyrilla in 1, 3, 7, and 14 days after spraying of different insecticides revealed that Imidacloprid, proved significantly effective with >62% mortality, when it was recorded at 1 DAS. Profenofos was the next best treatments with about 56% mortality. Malathion, Fipronil and Thiomethoxame were moderate in action with about 38% mortality. Azadirachtin was less effective with <28% mortality.
Among the different treatments, Azadirachtin proved least toxic to cocoons and egg masses of E. melanoleuca followed by Thiomethoxame and Fipronil on the basis of per cent reduction of cocoons and egg masses after 10 days treatments. Profenofos and Malathion were found moderately toxic whereas, Imidacloprid proved highly toxic.
The overall performance of Imidacloprid was found to be the best in improving the cane quality followed by Profenofos, Thiomethoxame and Fipronil.
The result, status obtained with respected to cane yield revealed that, application of Imidacloprid @ 0.5 ml/L (standard check) recorded the highest cane yield of 81.3 t/ha and 40.5% increase over untreated control (UTC). This was followed by Profenofos 50 EC @ 2m/L which recorded 78.2 t/ha and 35.0% increase over UTC, Malathion 50 EC @ 2ml/L recoerded 76.7 t/ha and 30.6% increase over UTC, Fipronil 5 SC @ 1ml/L recorded 75.6 t/ha and 32.5% increase over UTC. The next best treatments were Thiomethoxame 25 WG @ 1gm/L which is recorded 73.8 t/ha with 27.4% increase over UTC. Azadirachtin 0.15% @ 5ml/L also recorded significant increase in cane yield and % increase over UTC.
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