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A. Regupathy |
Total Records (
11 ) for
A. Regupathy |
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T. Ramasubramanian
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A. Regupathy
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Resistance to thiodicarb was diagnosed in the field population of Helicoverpa armigera from Tamil Nadu, India. Bouquet bioassay results in the laboratory indicated the level of resistance was 30.0 - 45.0% at recommended dose (1000g.a.i ha-1) of thiodicarb. The suppression of larval population and reduction of damage to bolls, squares, locules and kapas in the field also in agreement with the laboratory results. |
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T. Ramasubramanian
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A. Regupathy
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The relative fitness of pyrethroid selected populations of Helicoverpa armigera was studied by construction of age specific fecundity tables for F2,F7 and F14 generations of unselected, fenvalerate and cypermethrin selected populations. The net reproductive rate computed from the life table statistics indicated that the fitness of the pyrethroid selected populations decreased drastically as the population advanced to fourteenth generation. In F2 the net reproductive rate was 237.437, 231.359 and 228.24 for the unselected, fenvalerate and cypermethrin selected populations respectively. It came down to 123.677 and 121.432 for fenvalerate and cypermethrin selections respectively and only a marginal decline to 197.962 in unselected population. The decrease in fitness was greatly manifested through reproductive behaviour but not by the developmental traits. The variation in generation time was insignificant between the selected and unselected populations irrespective of the generations. |
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P. Duraimurugan
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A. Regupathy
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In the present study, the talc-based formulation of Pseudomonas fluorescens strain (Pf1) was tested against H. armigera in cotton, okra and pigeonpea. The susceptibility of H. armigera fed on P. fluorescens treated and untreated plants was bioassayed against cypermethrin on cotton bolls, okra fruits and pigeonpea pods. The susceptibility of third instar larvae of H. armigera to cypermethrin, fed on P. fluorescens treated plants did not differ significantly with the untreated plants. However, there was variation in the protein banding pattern among the P. fluorescens treated and untreated plants with or without infestation of H. armigera. Protein bands of molecular weight 83 and 40 kDa in cotton, 130 and 52 kDa in okra were observed in the Pseudomonas treated plants with infestation of H. armigera. |
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T. Ramasubramanian
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A. Regupathy
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Survey on insecticide resistance monitoring for a period of one year indicated that the Helicoverpa armigera population of Tamil Nadu developed very high level of resistance to synthetic pyrethroids, medium level of resistance to chlorpyrifos and quinalphos, low level of resistance to endosulfan, thiodicarb and profenofos and cent per cent susceptibility to the new chemistry spinosad. Synergistic studies with piperonyl butoxide, pungam oil and profenofos clearly indicated that the common MFO mechanism was responsible for the high level resistance observed to synthetic pyrethroids. |
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P. Duraimurugan
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A. Regupathy
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Push-pull strategy with conjunctive use of trap crops, neem and Trichogramma chilonis Ishii was evaluated against cotton bollworm, Helicoverpa armigera (Hubner) under field conditions. Neem seed kernel extract (NSKE) was applied on cotton crop leaving trap crops (okra and pigeonpea) commencing from 46 DAS at weekly interval to increase the pushing of H. armigera away from cotton. Application of NSKE on cotton improved the oviposition preference ratio from 1:1.35 and 1:1.40 to 1:3.02 and 1:2.43 on cotton:okra and cotton:pigeonpea, respectively. Egg parasitoid, T. chilonis cards were tagged after each application of NSKE on the trap crops. The percent parasitism of eggs of H. armigera on cotton sole crop system ranged from 14.8 to 16.4% and that on trap crops was 10.4 to 12.0 and 14.5 to 15.5% on okra and pigeonpea respectively. Cotton (treated with NSKE) + Trap crops (Trichogramma released) system recorded the lowest mean egg, larval population and fruiting bodies, boll and locule damage. The synthetic pyrethroids resistance in field survived H. armigera at the end of the season was reduced from 85.3-94.0 to 84.8 -92.1%. |
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T. Ramasubramanian
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A. Regupathy
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The bouquet bioassay experiments under laboratory condition revealed that the corrected percentage mortality of Helicoverpa armigera was 76.9-80.0% at recommended dose of spinosad. Good biological efficacy of this new molecule was also reflected in the suppression of larval population and reduction of damage to bolls, squares, locules and kapas in the field. |
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P. Duraimurugan
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A. Regupathy
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Studies were carried out to find the effects of joint action between Bacillus
thuringiensis subsp. aizawai (Bta) (Agree®) and
synthetic pyrethroids against third instar larvae of H. armigera on
different hosts. The joint action of Bta+pyrethroids at LC25+LC25
revealed supplemental synergism as the combined application on different hosts
showed 4.75-21.72 and 18.36-38.26% more than the expected mortality at LC50
of Bta alone and LC50 of pyrethroids alone, respectively. |
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P. Duraimurugan
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A. Regupathy
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Studies were carried out to assess the effects of stimulo-deterrent
diversionary strategy with trap crops, neem and Bacillus thuringiensis Berliner
in cotton for the management of insecticide resistant Helicoverpa armigera (Hubner)
at Agricultural Research Station, Vaigaidam and Agricultural Research Station,
Bhavanisagar, Tamil Nadu Agricultural University, Tamil Nadu during 2003-2004.
Field experiments were conducted on cotton (MCU7) with trap crops (okra and
pigeonpea) and neem was used to diversify the pests to trap crops where by the
control of these pest was assessed with the application of Bt (Delfin®). The
preference of H. armigera was towards okra and pigeonpea as a trap crop
compared to cotton. Application of NSKE on cotton diversified the H. armigera
towards untreated okra and pigeonpea. Stimulo-deterrent diversionary strategy
with conjunctive use of trap crops (okra and pigeonpea), restricted application
of NSKE on cotton leaving trap crops and restricted application of Bt on trap
crops was highly effective in reducing the incidence of H. armigera and
damage to fruiting bodies, boll, locule and inter locule basis over cotton sole
crop (untreated check). The percent recovery of Bt infected larvae varied from
43.3-48.8, 40.0-48.3 and 32.7-38.6% on okra, pigeonpea and cotton, respectively.
The synthetic pyrethroids resistance in field survived H. armigera at the
end of the season was reduced from 88.0-92.7 to 81.1-89.7%. |
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T. Ramasubramanian
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A. Regupathy
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In Helicoverpa armigera, withdrawal of selection pressure for fourteen consecutive generations resulted in 2.58 and 3.01 fold increase in the susceptibility to lambdacyhalothrin and betacyfluthrin, respectively. Similarly, continuous selection enhanced the resistance level to the extent of 6.77 and 7.14 fold to the respective pyrethroids. Populations selected for resistance to lambdacyhalothrin and betacyfluthrin showed positive cross resistance to all other pyrethroids tested and no cross resistance to endosulfan. The increased level of mixed function oxidases with advancement of generation favoured the positive cross resistance among the pyrethroids. |
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A. Suganthi
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S. Chandrasekaran
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A. Regupathy
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The bud worm, Hendecasis duplifascialis Hampson is one of the major pests of jasmine, Jasminum sambac. The pheromone release behaviour of the female was studied by making visual observations under a 12: 12D photoperiod. Most of the females (85.00%) called two days after emergence and majority of the females had multiple bouts of calling. The earliest initial calling was at 04.20 h. after the commencement of scotophase. The termination of calling was found to be as late as 10 min after the onset of photophase. Wind tunnel bioassay showed that two day old females were found to be more attractive to males and attraction was more pronounced in the presence of air current. |
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T. Ramasubramanian
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A. Regupathy
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The bouquet bioassay experiments under laboratory condition revealed that the percentage mortality of Helicoverpa armigera was more than 70% even at the lowest rate of 10 g a.i ha-1 (1/10th recommended dose) and the percentage survival was in the range of just 7.5-20.0% at the recommended dose of indoxacarb. Good biological efficacy of this new molecule was also reflected in the suppression of larval population and reduction of damage to bolls, squares, locules and kapas in the field. The increased susceptibility of pyrethroid resistant populations of H. armigera to indoxacarb in Tamil Nadu could be due to the activation by carboxyl esterases in to its more toxic metabolite. |
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