ECOLOGICAL NICHE, SEASONAL INCIDENCE, BIODIVERSITY AND MANAGEMENT OF PINK BOLLWORM, Pectinophora gossypiella (SAUNDERS) ON Bt COTTON 3662
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Date
2023-05
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JAU JUNAGADH
Abstract
The present investigation entitled “Ecological niche, Seasonal incidence,
Biodiversity and Management of pink bollworm, Pectinophora gossypiella
(SAUNDERS) on Bt cotton” was carried out at Cotton Research Station, J.A.U.,
Junagadh, Gujarat during kharif, 2020-21& 2021-22.
The survey was conducted in different Saurashtra districts viz., Junagadh,
Rajkot, Amreli and Surendranagar of Gujarat to know the intensity of pink bollworm
incidence in Bt cotton. The highest incidence of pink bollworm was noticed in
Junagadh district followed by Rajkot district of Gujarat during 2020-21. Whereas in
2021-22, the highest pink bollworm infestation was noticed in Amreli district
followed by Rajkot district of Gujarat. Also in both these years, Surendranagar district
recorded a very less incidence of pink bollworm compared to Junagadh, Rajkot and
Amreli districts.
In the Saurashtra region, three species of pink bollworm viz., Pectinophora
gossypiella (Saunders), Pectinophora scutigera (Holdaway) and Pectinophora
endema (Common) were recorded.
The incidence of pink bollworms on rosette flowers commenced from the 37th
Standard Meteorological Week (SMW) during 2020-21. The initial per cent rosette
flower count i.e. 10.48% rosette flower was observed at the 37th SMW and escalated
to 13.39% rosette flower during the 40th SMW. In the case of per cent green boll
damage commenced from the 43rd SMW 7.56% green boll damage and escalated to
16.20% green boll damage during the 48th SMW. The peak incidence of PBW larvae
per 10 bolls was observed during the 48th SMW of the year, with 6.00 larvae/10 bolls.
During 2021-22, rosette flower initiation was started (1 per cent) from the 33rd
Standard Meteorological Week (SMW) and formed a peak (12.70 per cent) during the
43rd SMW. Further coming to per cent green boll damage by pink bollworm on
cotton, commenced from the 43rd SMW and continued till the 52nd SMW. In addition
to the PBW larvae per 10 bolls were noticed from the 41st SMW and continued till the
52nd SMW.
In addition to this, locule damage and open boll damage during 2020-21 locule
damage were 20.68 and 21.80 per cent during 1st and 2nd picking, respectively.
Whereas, open boll damage was 26.88 and 28.40 per cent during 1st and 2nd picking,
respectively. Also during 2021-22, locule damage was 19.80 and 20.60 per cent
during 1st and 2nd picking, respectively. Whereas, open boll damage was 24.40 and
26.20 per cent during 1st and 2nd picking, respectively.
During the biodiversity study period 2020 and 2021, P. gossypiella was the
most abundant contributing with the maximum relative abundance of P. gossypiella in
Saurashtra region.
Based on Pectinophora sequences available online in the NCBI Gene Bank
portal, the percentage of similarity ranged from 100 to 97.00 per cent and pair-wise
genetic distance between the isolates of Saurashtra ranged from 2.16 to 5.57 with an
average of 1.446 thereby indicating very low genetic variation between the
Pectinophora isolates.
Validation of IPM module and farmer practices the result indicated that the
range of per cent rosette flower by pink bollworm during 2020-21 was 0.79 to 2.35
per cent and 5.45 to 6.50 per cent recorded from 50 to 65 DAS in IPM module and
farmer practices, respectively. The per cent green boll damage was 2.18 to 2.60 per
cent and 11.24 to 15.9 per cent recorded from 120 to 150 DAS in IPM module and
farmer practices, respectively. During 2021-22, per cent of the rosette flowers by pink
bollworm was 0.67 to 1.97 per cent and 5.37 to 6.13 per cent recorded from 50 to 65
DAS in IPM module and farmer practices, respectively. The per cent green boll
damage was 1.98 to 2.23 per cent and 10.83 to 16.20 per cent recorded from 120 to
150 DAS in IPM module and farmer practices, respectively.
Seed cotton yields during 2020-21 & 2021-22 were recorded at 3321 kg/ha and
3455 kg/ha in the IPM module, respectively. Further coming to farmer practices
during 2020-21 & 2021-22, it was 1778 kg/ha and 1870 kg/ha seed cotton yield,
respectively.
Considering the Incremental Cost-Benefit Ratio (ICBR) of both the treatments
against pink bollworm in cotton showed that the yield increased over control was
1564 kg/ha and net realization was 73,720 Rs./ha recorded in the IPM module as
compared to farmer practices