Studies on efficacy and persistence of insecticides against shoot and fruit borer, Leucinodes orbonalis (Guenee) on brinjal
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Date
2023-03
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CCSHAU, Hisar
Abstract
Studies on efficacy and persistence of insecticides against shoot and fruit borer, Leucinodes
orbonalis (Gueene) were conducted at CCS Haryana Agricultural University, Hisar, Haryana during Kharif
2020 and 2021. Insecticides viz., chlorantraniliprole 18.5% SC, emamectin benzoate 5% SG, spinosad 45%
SC, thiacloprid 20.70% SC, cypermethrin 3% + quinalphos 20% EC, pyriproxyfen 5% + fenpropathrin 15%
EC and betacyfluthrin 8.49% + imidacloprid 19.8 % OD were applied at recommended dose of 200, 200,
187, 750, 400, 750 and 200 g or ml ha-1. Results revealed that spinosad and pyriproxyfen+ fenpropathrin
were most effective against L. orbonalis reducing 70.48 and 69.82 per cent shoot infestation; 74.39 and
70.18 per cent fruit infestation (number basis); 76.53 and 73.21 per cent fruit infestation (weight basis) over
control with increase in yield of 109.74 and 97.23 per cent over control, respectively. Chlorantraniliprole and
emamectin benzoate were found next in order of effectiveness. On the other hand, treatments with
thiacloprid, cypermethrin + quinalphos and betacyfluthrin + imidacloprid were comparatively less effective.
Applications of betacyfluthrin + imidacloprid and pyriproxyfen+ fenpropathrin caused maximum reduction
of whitefly (57.79 and 56.38%) and leafhopper (63.76 and 61.32%) while lowest reduction was recorded in
case of emamectin benzoate (30.23, 24.46%) and spinosad (29.40 and 25.70%). Chlorantraniliprole,
emamectin benzoate, spinosad and pyriproxyfen + fenpropathrin were found to be relatively safer for natural
enemies (coccinellids and spiders) whereas treatments with thiacloprid, betacyfluthrin + imidacloprid and
cypermethrin + quinalphos caused more than 50 per cent reduction over control in the population.
Emamectin benzoate with LC50 of 0.32 ppm was 4.84 times toxic than chlorantraniliprole with LC50 of 1.55
ppm against first instar larvae of L. orbonalis. Dissipation of chlorantraniliprole in brinjal fruits followed
first-order kinetics and residue reached below limit of quantification (0.01 mg kg-1) on 10th and 15th days of
application with half-life and waiting period of 1.47 to 1.65 days and 6.48 to 6.76 days at recommended dose
while 2.04 to 2.57 days and 10.75 to 12.67 days at double of recommended dose, respectively during kharif
2020 and 2021. In case of combination insecticide (pyriproxyfen 37.5 + fenpropathrin 112.5 g a.i. ha-1)
residue level reached below detectable level after 7 (single dose) and 10 days of spray (double dose) for
pyriproxyfen and 10 (single dose) and 15 days of spray (double dose) in case of fenpropathrin. Half-life for
pyriproxyfen was calculated to be 1.92 and 2.19 days while in case of fenpropathrin, it was 3.13 and 3.62
days at single and double doses, respectively during kharif 2020 whereas half-life of 1.82 and 1.57 days
(pyriproxyfen) and 3.07 and 3.62 days (fenpropathrin) were calculated during kharif 2021 at corresponding
doses. Harvest time residues in soil were found below the limit of quantification (LOQ). Waiting periods of
8.46 and 12.35 days (kharif 2020); 8.70 and 12.96 days (kharif 2021) were suggested in case of pyriproxyfen
at single and double doses, respectively while 3.32 and 6.92 days (kharif 2020); 3.00 and 7.13 days (kharif
2021) were suggested at single and double doses of fenpropathrin, respectively. Dipping of brinjal fruits in
baking soda solution (2%) resulted in maximum removal (63-71%) of chlorantraniliprole residues while
dipping in lemon water resulted in maximum reduction of 52-66 and 60-47 per cent residues of pyriproxyfen
and fenpropathrin, respectively.