Dr. M. F. ACHARYAVARIYA MAYUR VISHNUBHAI10101190372023-12-272023-12-272023-05https://krishikosh.egranth.ac.in/handle/1/5810204568The 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 practicesEnglishThesis