M ONITORING ACARICIDE RESISTANCE IN TWO SPOTTED SPIDER MITE, Tetranychus urticae Koch (A cari: Tetranychidae) INFESTING TOMATO
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Date
2008-08-12
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University of Agricultural Sciences, Bangalore
Abstract
Investigations w ere carried out to determ ine the base-line values for susceptibility of laboratory population of T. urticae to selected acaricides, to monitor the level of resistance to acaricides in T. urticae populations on tomato from Bangalore and
Kolar districts and field evaluation of neweracaricidal molecules against this mite pest
on tomato. The susceptibility of laboratory population of T. urticae to wettable sulphur,
dicofol, abamectin, diafenthiuron, fen azaqu in and propargite increased over successive
generations (from 5th to 38"’ generation). The base line values for the susceptible
laboratory population at die 38th generation were 114 ppm for wettable sulphur, 0.1 ppm
each for dicofol, abam ectin, fen azaqu in & diafen thiuron and 0.3 ppm for propargite.
The level of resistance to wettable sulphur in T. urticae populations from tomato crop in Bangalore and Kolar district was low tomoderate as the resistance ratio ranged
from 3.2 to 38.1. For dicofol, resistance was high inbodi Bangalore (767 to 3690 folds)
and Kolar districts (500 to 6491 folds). For abamectin the resistance was low in Kolar
district (RR <10). Fordiafen thiuron resistance level was moderate in both Bangalore and
Kolar districts (RR 14-37 an d 18-47, respectively). How ever, die resistance level
increased to higher levels of 67 an d 79 folds during December 2007 and February 2008.
For fenazaquin, mite populations from Bangalore and Kolar districts show edprogressive resistance from low tomoderate level (RR 5 to 32) as the tom atocropping
season advanced, but resistance was high (168 - 249 folds) in V ad ag u r of Kolar district
beyond September. Low levels of resistance (4-12 folds) to propargite in Bangalore and
Kolar districts during kharif increased to a moderate level during December 2007 and
February 2008. Field evaluation of new eracaricides against T. urticae in V ad aguro f Kolar district revealed better effectiveness witiimilbemectin (3.75 ga .i./ha ), fenazaquin (125 g
a .i./ha ), propargite (570 g a .i./ha ), chlorfenapyr (75 g a .i./ha ) and fenpyroxim ate (30 g
a .i./ha ), which accounted for 70% reduction in the egg population of spider mite.
Chlorfenapyr, fenazaquin and propargite were superior in bringing down the
population of active stages by 75 to 91%. How ever, against mixed stage population,
milbemectin and fenazaquin causing 82-83% reduction were significandy more effective
followed by propargite, chlorfen apyr and fenazaquin causing 70-76% reduction. The
effect of diafen thiuron (450 g a .i./h a ), abam ectin (6 g a .i./h a ) and mineral oil 1% was
moderate record in g 61 - 66% reduction.
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