MONITORING OF INSECTICIDE RESISTANCE IN COTTON LEAFHOPPER, Amrasca biguttula biguttula (Ishida) AND ITS MANAGEMENT
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2011
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Abstract
Studies on “Monitoring of insecticide resistance in cotton leafhopper,
Amrasca biguttula biguttula (Ishida) and its management” was taken up during
kharif 2010 to determine the insecticide resistance in cotton leafhopper to major
insecticides viz., monocrotophos, dimethoate, acephate, imidacloprid, acetamiprid,
thiamethoxam and fipronil and to manage it.
The population of cotton leafhopper was tested against test insecticides
viz., monocrotophos, dimethoate, acephate, imidacloprid, acetamiprid,
thiamethoxam and fipronil following the leaf dip method. The mortality data was
subjected to probit analysis and the LC50 and LC90 values were calculated. The
LC90 values were also compared with the recommended concentrations of the
respective insecticides (AICCIP, 2010). The relative degree of resistance acquired
by leafhopper population to monocrotophos, imidacloprid and thiamethoxam was
calculated by comparing the LC50 values with values of kharif 1999 reported by
Chalam and Subbaratnam (1999). At LC50 cotton leafhopper developed 16.67 and
47.50 fold resistance to imidacloprid and thiamethoxam and there was no
resistance to monocrotophos.
Dimethoate and fipronil were seven times more toxic than monocrotophos
while acephate, imidacloprid, acetamiprid and thiamethoxam were less toxic than
monocrotophos at LC50. Dimethoate and fipronil were 7.04 and 2.47 times more
toxic while acephate, imidacloprid, acetamiprid and thiamethoxam were less toxic
than monocrotophos at LC90.
The order of toxicity of insecticides at LC50 is dimethoate ≥ fipronil >
monocrotophos > acephate > imidacloprid > thiamethoxam > acetamiprid and at
LC90 it is dimethoate > fipronil > monocrotophos > imidacloprid > acephate >
thiamethoxam > acetamiprid.
In the management trial, the efficacy of insecticides against cotton
leafhopper was studied. The experiment was laid out with eleven treatments
including untreated control and replicated thrice in a simple Randomized Block
Design. The treatments were imposed four times with an interval of 10 days. The
incidence of leafhoppers per three leaves per plant was recorded on five randomly
selected plants per plot one day before and 1st, 3rd, 7th and 10th day after treatment.
All the insecticides tested were significantly superior over untreated control
by recording lower leafhopper population except T1 (Seed treatment with
imidacloprid 70 WS 5 g/kg) and T2 (Seed treatment with imidacloprid 70 WS 5
g/kg + stem application with monocrotophos 36 SL (1:4)) which were at par with
untreated control. Among the different treatments tested T7 (Seed treatment with
imidacloprid 70 WS 5 g/kg + stem application with monocrotophos 36 SL (1:4)
and spraying of imidacloprid 17.8 SL @ 0.5 ml/l + spraying of acephate 75 SP @
1.5 g/l + spraying of fipronil 5 SC @ 2 ml/l) was found to be superior against
leafhoppers, followed by T5 (Seed treatment with imidacloprid 70 WS 5 g/kg +
stem application with monocrotophos 36 SL (1:4) + spraying of fipronil 5 SC @ 2
ml/l) and are at par with the remaining treatments.
Highest yield of 1497 kg/ha was recorded in T7 (Seed treatment with
imidacloprid 70 WS 5 g/kg + stem application with monocrotophos 36 SL (1:4)
and spraying of imidacloprid 17.8 SL @ 0.5 ml/l + spraying of acephate 75 SP @
1.5 g/l + spraying of fipronil 5 SC @ 2 ml/l) and is significantly at par with
remaining treatments except, T1(Seed treatment with imidacloprid 70 WS 5 g/kg),
T2 (Seed treatment with imidacloprid 70 WS 5 g/kg + stem application with
monocrotophos 36 SL (1:4)) and untreated control which were significantly
inferior to all other treatments.
Description
Keywords
cotton, insecticides, sowing, monocrotophos, seed treatment, toxicity, concentrates, pesticide resistance, crops, biological phenomena, INSECTICIDE RESISTANCE, COTTON LEAFHOPPER, Amrasca biguttula biguttula (Ishida)