Dr. N. MALLIKHARJUNA RAOSRINU, KORUPAKALA2018-08-082018-08-082017http://krishikosh.egranth.ac.in/handle/1/5810063663D5422A field experiment entitled “Monitoring of stem borer species and their egg parasitoids in irrigated rice ecosystem” was conducted at Andhra Pradesh Rice Research Institute (APRRI) & Regional Agricultural Research Station (RARS), Maruteru, West Godavari district during kharif and rabi, 2016-17, respectively to study the influence of weather parameters on the occurrence of rice yellow stem borer (YSB) Scirpophaga incertulas (unprotected), species composition of different rice stem borers and record the occurrence of different egg parasitoids in the rice ecosystem. Incidence of YSB observed from the 35th standard meteorological week (SMW) i.e., the first week of September (1.93 % Dead hearts ) and attained peak infestation during 40th SMW (7.53 % DH) and continued up to 47nd SMW with 2.07 per cent white ears during kharif, 2016-17, during rabi, 2016-17 it was started from the 4th SMW (last week of January) with 2.10 per cent DH with the peak infestation at 7th SMW (6.28 % DH) and continued up to 12th SMW (2.84 % WE). The results of correlation studies on field infestation of YSB with weather parameters indicated that a significant and positive correlation with evening relative humidity during kharif, 2016-17 and there was no significant correlation was existed with other parameters during both the seasons. The predominant stem borer larval species observed were YSB (83.14 %), DHSB (15.86 %) and PSB (1.00 %) during kharif, 2016-17, YSB (89.86 %) and DHSB (10.14 %) during rabi, 2016-17. Among the diversity indices Simpson index and Evenness indicated more diversity and no evenness among the species during both the seasons. The relative abundance of light trap catches indicated that YSB (96.70 and 98.36 %) were more dominant followed by DHSB (3.30 and 1.64 %) and PSB S. inference light trap catches were nil during kharif and rabi, 2016-17, respectively. In light trap catches, the YSB moths were appeared maximum at 38th SMW (2071) and the minimum during 34th SMW (15), DHSB moths was noticed highest at 45th SMW (81) and lowest in 41st SMW (9) during kharif, 2016-17. The light trap catches of YSB population had a significant and positive correlation with minimum temperature (0.631) and rainfall (0.486). In contrast, the light trap catches of DHSB population showed a significant and negative correlation with minimum temperature (- 0.631) and rainfall (-0.486). In light trap catches, the YSB moth was maximum at 15th SMW (1137) and the minimum at 6th SMW (27). DHSB moth was highest at 12th SMW (17) and lowest was observed at 6, 7, 8 and 9th SMWs (5) during rabi, 2016-17. Light trap catches of YSB population had a significant and positive correlation with minimum temperature (0.549) and evening relative humidity (0.687). In reverse, DHSB adult population established a significant and positive correlation with morning relative humidity (0.617) and significant and negative correlation with maximum temperature (-0.820). In pheromone trap, YSB male moth catches were maximum at 42nd SMW (18), 7th and 9th SMW (8) during kharif and rabi, 2016-17, respectively. Pheromone trap catches of YSB moths showed a significant and negative correlation with morning relative humidity (-0.638) during kharif, 2016-17. Among the stem borer species, YSB egg mass was parasitized by, Telenomus spp, Trichogramma spp, and Tetrastichus spp, between 34th to 51th SMW. Telenomus spp (42.1 per cent and 37.4 per cent) effected maximum egg parasitism followed by Tetrasticus Spp (0.2 per cent and 3.3 per cent) and Trichogramma spp (0.00 per cent and 7.5 per cent) during kharif and rabi 2.16-17. However, the DHSB was parasitized only by Trichogramma spp. alone between 47th to 51th SMW (27.92 to 51.66 per cent).en-USnullThesis