Bioefficacy and persistence of novel insecticides against Helicoverpa armigera (Hubner) in chickpea and their leaching behaviour in soil
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Date
2020
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CCSHAU, Hisar
Abstract
The present studies on Bioefficacy and persistence of novel insecticides against Helicoverpa
armigera (Hubner) in chickpea and their leaching behaviour in soil were conducted at Pulses Research
Farm, CCS HAU Hisar during Rabi 2017-18 and 2018-19. The population dynamics studies of H. armigera
revealed that the peak larval population of H.armigera reached 5.50 and 5.71 larvae/mrl in 14th and
15thSMW during 2017-18 and 2018-19, respectively. The correlation studies showed that H. armigera
population had positive and significant correlation with maximum, minimum temperature and wind velocity
while significant negative correlation with morning and evening relative humidity was observed during both
of the years. There was non significant negative correlation between larval population and rainfall while non
significant positive correlation was found with sunshine hours in both years. The efficacy studies showed
that chlorantraniliprole 18.5 SC was the most effective treatment with 0.41 larva/mrl followed by
flubendiamide 39.35 SC (0.57 larva/mrl). The least effective treatment was Bacillus thruiengensis 5 WP
with highest number of larval count of 1.09 larvae/mrl followed by lambda cyhalothrin 5 EC (0.96 larva/mrl)
and quinalphos 25 EC (0.93 larva/mrl). The pooled data of yield showed that chlorantraniliprole 18.5 SC
treated plots were found to be significantly superior over other treatments with mean increase of 51.34 per
cent over control plot while the plots treated with bacillus thruiengensis 5 WP provided a yield of 1236.11
kg per ha with a mean increase of 16.29 per cent over control. The pooled data of per cent pod damage
showed that chlorantraniliprole 18.5 SC treated plots showed 8.31 per cent pod damage while the plots
treated with bacillus thruiengensis 5 WP were affected by 17.71 per cent pod damage. The avoidable losses
(pooled) during 2017-18 and 2018-19 accounted for 49.61 per cent with mean number of larvae per mrl 6.50
times lower under protected conditions. Mean yield (kg) per hectare was 2.0 times higher in protected
conditions. Highly significant positive correlation between larval population of H. armigera and percent pod
damage while negative correlation was observed between larval population and the yield obtained under
both protected and unprotected conditions. Similarly, negative correlation was observed between percent
pod damage and the yield obtained under both conditions. The dissipation kinetics of residues of
chlorantraniliprole and flubendiamide at both single and double doses followed the first order kinetics in
chickpea leaves and pods during both of the years. The residues of both insecticides in chickpea leaves and
pods reached below LOQ after 7th and 10th day of application at single and double doses, respectively. The
half lives (days) were less in double dose as compared to the single dose for both of the insecticides in both
chickpea leaves and pods during the two years. The results also showed that terminal residues of
chlorantraniliprole and flubendiamide were below LOQ in chickpea grain, straw and soil. The results
for leaching behaviour revealed that maximum retention of 75.20 and 78.90 per cent was observed in 0-5 cm
layer of soil only at single (40μg) and double dose (80μg) for chlorantraniliprole. For flubendiamide, it was
observed that the insecticide was confined in upper soil layers (0-10cm) with 85.86 and 89.10 per cent
retention at single (36μg) and double dose (72μg), respectively. None of the leachate fractions showed the
presence of both insecticides at both single and double dose.